depth of field with different lenses
Troy Piggins
discussions in the SI thread digression about depth of field at
same aperture but different focal lengths. No, I didn't use a
tripod. No, the focus point is not exactly the same. But it's
near enough to express what we're talking about.
This shot was taken at f/2.8 with a 150mm lens:
http://piggo.com/~troy/images/usenet/091216-dof/150mm-f2_8.jpg
This shot was taken at f/2.8 with a 35mm lens, roughly same
focusing distance as first shot:
http://piggo.com/~troy/images/usenet/091216-dof/35mm-f2_8-full.jpg
This was the second shot cropped down to roughly the same field
of view as the 150mm lens shot:
http://piggo.com/~troy/images/usenet/091216-dof/35mm-f2_8-crop.jpg
With the wider focal length lens, same aperture, same camera,
same focus distance, there is more stuff acceptably in focus.
--
Troy Piggins
Alan Browne
Thanks for doing that. Answered a question I wasn't sure about.
If I get a chance I'll so something similar.
Wally
First of all, good for you for doing tests. You will learn real
things. Experiments beat theory.
Secondly, you are right, shooting with a wide angle lens and then
cropping to the same image size will give you much better DOF.
But thirdly, if you move in with the wide angle to get the same image
size, then the DOF will be the same.
Except that it might not be -- I suspect the latter case will show the
long lens to give better DOF. That's because the exit pupil is
usually smaller than expected for tele lenses. Look at the front of
the lens, then at the back. Do the apertures look the same size? It
will probably look smaller from the back, and that should give better
DOF.
Wally
John McWilliams
> On Wed, 16 Dec 2009 08:30:30 +1000, Troy Piggins
> <usene...@piggo.com> wrote:
>
>> Really rough real world test to prove to myself recent
>> discussions in the SI thread digression about depth of field at
>> same aperture but different focal lengths. No, I didn't use a
>> tripod. No, the focus point is not exactly the same. But it's
>> near enough to express what we're talking about.
>>
>> This shot was taken at f/2.8 with a 150mm lens:
>> http://piggo.com/~troy/images/usenet/091216-dof/150mm-f2_8.jpg
>>
>> This shot was taken at f/2.8 with a 35mm lens, roughly same
>> focusing distance as first shot:
>> http://piggo.com/~troy/images/usenet/091216-dof/35mm-f2_8-full.jpg
>>
>> This was the second shot cropped down to roughly the same field
>> of view as the 150mm lens shot:
>> http://piggo.com/~troy/images/usenet/091216-dof/35mm-f2_8-crop.jpg
>>
>> With the wider focal length lens, same aperture, same camera,
>> same focus distance, there is more stuff acceptably in focus.
>
>
> First of all, good for you for doing tests. You will learn real
> things. Experiments beat theory.
>
> Secondly, you are right, shooting with a wide angle lens and then
> cropping to the same image size will give you much better DOF.
Except many of us prefer "better" to mean more limited. Or more control.
Thus, longer lenses in general give "better" results than shorter ones
for the same subject.
--
John McWilliams
Troy Piggins
>> of view as the 150mm lens shot:
>> http://piggo.com/~troy/images/usenet/091216-dof/35mm-f2_8-crop.jpg
>>
>> With the wider focal length lens, same aperture, same camera,
>> same focus distance, there is more stuff acceptably in focus.
>
> First of all, good for you for doing tests. You will learn real
> things. Experiments beat theory.
>
> Secondly, you are right, shooting with a wide angle lens and then
> cropping to the same image size will give you much better DOF.
>
> But thirdly, if you move in with the wide angle to get the same image
> size, then the DOF will be the same.
>
> Except that it might not be -- I suspect the latter case will show the
> long lens to give better DOF. That's because the exit pupil is
> usually smaller than expected for tele lenses. Look at the front of
> the lens, then at the back. Do the apertures look the same size? It
> will probably look smaller from the back, and that should give better
> DOF.
The perspective is different too. That's not what I was trying
to test. As to whether the DoF will be the same, don't know and
don't care at the moment. I was trying to illustrate a point
raised in another thread.
I know if you move closer, ie reduce focus distance, the DoF
narrows as well. So it makes sense that at some point if you
take a shot with a longer lens, and another shot closer to the
subject with the same aperture, you could end up with
similar/same DoF. But the perspectives will be different, and
the field of view may or may not be the same.
--
Troy Piggins
Allen
Good Pictures" from Kodak for something like 50 cents. (I believe this
edition was from 1939 or 1940.) It was a wonderful introduction to
photography. Many of the questions I see here (basic lighting, posing,
composition, optics, depth of field, shutter speeds, filters and
such--and an intro to darkroom work, useless now) are answered in that
70 year old, approximately 150 page book. Looking in bookstores, I don't
see anything like that book. What I see now weigh as much as a 4x5
Graflex (a conparison from the time when that book was published) and
difficult to find answers to your questions. I practically wore the ink
off the pages in a year. We need a digital-age equivalent.
Allen
John McWilliams
I am pretty sure we do have that, but it's not on usenet. Finding and
weeding out the web based tutorials, video tutorials would be the
digital equivalent of the great Kodak primer.
--
John McWilliams
Troy Piggins
> Troy Piggins wrote:
> [---=| Quote block shrinked by t-prot: 33 lines snipped |=---]
>> take a shot with a longer lens, and another shot closer to the
>> subject with the same aperture, you could end up with
>> similar/same DoF. But the perspectives will be different, and
>> the field of view may or may not be the same.
>>
> In 1941, when I was 12 years old, I bought a book titled "How to Make
> Good Pictures" from Kodak for something like 50 cents. (I believe this
> edition was from 1939 or 1940.) It was a wonderful introduction to
> photography. Many of the questions I see here (basic lighting, posing,
> composition, optics, depth of field, shutter speeds, filters and
> such--and an intro to darkroom work, useless now) are answered in that
> 70 year old, approximately 150 page book. Looking in bookstores, I don't
> see anything like that book. What I see now weigh as much as a 4x5
> Graflex (a conparison from the time when that book was published) and
> difficult to find answers to your questions. I practically wore the ink
> off the pages in a year. We need a digital-age equivalent.
> Allen
I haven't read it, but I see "Understanding Exposure" by Bryan
Peterson recommended a lot. According to Amazon.com it runs at
about 160 pages.
--
Troy Piggins
Troy Piggins
> Allen wrote:
> [---=| Quote block shrinked by t-prot: 42 lines snipped |=---]
>> 70 year old, approximately 150 page book. Looking in bookstores, I don't
>> see anything like that book. What I see now weigh as much as a 4x5
>> Graflex (a conparison from the time when that book was published) and
>> difficult to find answers to your questions. I practically wore the ink
>> off the pages in a year. We need a digital-age equivalent.
>
> I am pretty sure we do have that, but it's not on usenet. Finding and
> weeding out the web based tutorials, video tutorials would be the
> digital equivalent of the great Kodak primer.
They still print books these days, you know. ;)
--
Troy Piggins
Robert Coe
It may depend somewhat on the design of the lens. As I understand it, a common
design of a telephoto lens is to form an image, then magnify it. The
magnification will affect the in-focus and out-of-focus parts of the image
equally. The magnified OOF points will exceed their circle of confusion first,
which I guess is the definition of loss of DOF.
Bob
John McWilliams
Barely! ...... You trying to put KINDLing under my fire??!
Great point, but I was trying to be oh-so-modern!
--
john mcwilliams
Robert Coe
Of the books my wife and I have in the house, the one most like what you're
looking for may be "Digital Photography for Dummies" by Julie Adair King
(Wiley Publishing, Inc.). We have the 5th (2005) edition; there are probably
newer ones.
Bob
Troy Piggins
I'm not sure what you're saying here. The above real-world
example holds true for every lens I've used. That's all I care
about. Real world results and experiences. That other thread is
getting drowned with definitions of DoF, circles of confusion,
pedantry and theory. Just grab your camera, take some photos
people. I didn't even need to leave my desk for the above shots.
Sorry mate, I'm not directing this at you personally. Just
having a frustrating day and am over the pedantry - here and at
work.
--
Troy Piggins
Troy Piggins
> Troy Piggins wrote:
> [---=| Quote block shrinked by t-prot: 8 lines snipped |=---]
>>> I am pretty sure we do have that, but it's not on usenet. Finding and
>>> weeding out the web based tutorials, video tutorials would be the
>>> digital equivalent of the great Kodak primer.
>>
>> They still print books these days, you know. ;)
>
>
> Great point, but I was trying to be oh-so-modern!
Hehe. TBH I've always used websites, forums, USENET for
technical information and thought of books more for reading
novels. Even back in University days I wasn't that big on text
books. But recently I've been getting a few reference books. :)
--
Troy Piggins
Bill Graham
"Troy Piggins" <usene...@piggo.com> wrote in message
news:2009121...@usenet.piggo.com...
of storage, and you can buy that much and put it on your home computer for
around a thousand dollars. The only thing that is holding up making that
entire library available to everyone on line is the billing
problem......IOW, how would you bill people for their usage of all that
copyrighted material?
JimKramer
OK
That will take you to a directory.
ATTENTION!: the PSD file there is 87MB
Shot on a tripod with the Canon 28-135. F8. @28, 50, 100, 135 in four lined
up layers. OH look, there's no difference other than a crappy lens. I
really like that lens until I did this with it. Yuck! What a load of
distortion, but you will still get the point.
Troy the problem with your test is you were using a macro lens as one of the
lenses, it has been engineered to give a particularly flat field and that
makes it behave differently than a normal lens, Please try it again with
normal lenses or a zoom on a tripod.
-Jim
Robert Coe
wrote:
: * Robert Coe wrote :
Not trying to be pedantic; just grasping at some theoretical underpinning for
your observations. It's an article of faith that telephoto lenses have lower
DOF, but the reasoning behind it is seldom explained. I don't pretend to be an
oracle (I'm a computer programmer, not an optical designer), but I know a
little more physics than the average yokel and am interested in why things are
the way they are.
I haven't yet gotten to the references to circles of confusion in the other
thread. My laziness may have led me into unnecessary repetition, for which I
apologize.
Bob
Troy Piggins
>> http://piggo.com/~troy/images/usenet/091216-dof/35mm-f2_8-crop.jpg
>>
>> With the wider focal length lens, same aperture, same camera,
>> same focus distance, there is more stuff acceptably in focus.
>
> OK
>
> http://jlkramer.net/rpe35/
>
> That will take you to a directory.
>
> ATTENTION!: the PSD file there is 87MB
>
> Shot on a tripod with the Canon 28-135. F8. @28, 50, 100, 135 in four lined
> up layers. OH look, there's no difference other than a crappy lens. I
> really like that lens until I did this with it. Yuck! What a load of
> distortion, but you will still get the point.
>
> Troy the problem with your test is you were using a macro lens as one of the
> lenses, it has been engineered to give a particularly flat field and that
> makes it behave differently than a normal lens, Please try it again with
> normal lenses or a zoom on a tripod.
What were you focusing on? The grill of the car is blurry in
some shots and sharper in others. Same with the grass. What was
the aperture? If we're trying to see apertures and DoF, surely
we need sharp shots.
Sorry mate. I understand how you were trying to present it and
like the idea, but think the execution let it down. At those
sort of distances with telephoto, the DoF is quite broad. I
reckon you need to focus much closer to get a narrower DoF, and
use a wide aperture to accentuate it also.
--
Troy Piggins
Troy Piggins
<snip />
> Not trying to be pedantic; just grasping at some theoretical underpinning for
> your observations. It's an article of faith that telephoto lenses have lower
> DOF, but the reasoning behind it is seldom explained. I don't pretend to be an
> oracle (I'm a computer programmer, not an optical designer), but I know a
> little more physics than the average yokel and am interested in why things are
> the way they are.
>
> I haven't yet gotten to the references to circles of confusion in the other
> thread. My laziness may have led me into unnecessary repetition, for which I
> apologize.
It's all good. It does help to understand the physics of it, I
guess. I'm a bit like that too, I suppose. Just not today. :)
--
Troy Piggins
Paul Furman
Many strange things happen to optics at close distances. Normal
photography rules are quoted for 'at infinity' or thereabout. But I
think the explanation for your results isn't effected by that too
much... you have to be even closer before things get really weird. The
main thing is that aperture isn't the same as f/stop. Those lenses have
different sized openings/apertures for their respective f/stops. The
opening determines the DOF, the focal length determines the
FOV/crop/magnification.
One imperfect simple formula for effective aperture (f/stop) with
closeups is f(mag+1) where f = f/stop and magnification is like 1:1 as
1x. It's hard to tell but Troy's 150mm shot might be about 100m to the
16mm frame height, so about 0.16x. Then 2.8x(1.16)=f/3.25, just slightly
different from f/2.8 as read on the aperture ring. This is approximate
but is probably in the ballpark.
For Jim's pdf test, I'm not sure how to explain the results other than
everything is in focus at f/8 near infinity anyways and we're only
seeing the difference in sharpness at various focal lengths. The lens
seems lacking for long zoom and fine for wide angle. If you zoom in
beyond 100% the long zoom looks worse because it has been reduced to
fit. Anyways, opened up; the long zoom should show less DOF at the same
f/stop, which is a larger diameter aperture than the wide angle view at
the same f/stop which has a smaller aperture diameter and should show
more DOF like Troy's closeup tests.
--
Paul Furman
www.edgehill.net
www.baynatives.com
all google groups messages filtered due to spam
Paul Furman
> if you move in with the wide angle to get the same image
> size, then the DOF will be the same.
Maybe, I'm not sure. If so, it's because a zoom will adjust the aperture
to a constant f/stop while zooming. Anyways changing position isn't what
this discussion is about although I'll admit that's a commonsense idea
which is ultimately relevant but not in the specific context I'm
thinking of.
> Except that it might not be -- I suspect the latter case will show the
> long lens to give better DOF. That's because the exit pupil is
> usually smaller than expected for tele lenses. Look at the front of
> the lens, then at the back. Do the apertures look the same size? It
> will probably look smaller from the back, and that should give better
> DOF.
I think the minor difference in exit pupil position and lens length in a
telephoto versus non-telephoto lens doesn't matter much. A non-telephoto
simple long lens is longer and in the simplest scenario, the entrance
pupil might be inside the single element where a 'tricky' telephoto
modern design is shorter and the entrance pupil might be somewhere in
the middle of the lens for the front... which does change the
perspective slightly... but not much. And none of that effects DOF much
either at normal non-macro distances.
Paul Furman
>
> Anyways, opened up; the long zoom should show less DOF at the same
> f/stop, which is a larger diameter aperture than the wide angle view at
> the same f/stop which has a smaller aperture diameter and should show
> more DOF like Troy's closeup tests.
I just want to emphasize this point.
It is a confusing topic.
Jim Bob
Missed that discussion, however maybe worth reading this:
http://www.luminous-landscape.com/tutorials/dof2.shtml
Calvin Sambrook
I also got my camera out today and the shots are here:
http://picasaweb.google.co.uk/csambrook/LensDoFTests#
See my post on the original thread for a painfully technical explanation or
if you prefer the real world just look at "18mm F5.6 cropped" and "300mm
F5.6 F5.6 equivalent" to see the fact that the DoF is very different.
Sadly as neither of these is 50mm I can't use them as my entries :-)
MikeWhy
news:hgaqf8$g2c$1...@news.eternal-september.org...
Harold Merklinger's web books apply some mathematical rigor to the topic of
focus and depth of field. They're free for the download, and well worth the
web search. He asks for a $5 donation, which I believe is well worth the
clarity and insight he brings to this murky and ill understood topic.
(Punning is unavoidable and not intended.)
"Ins and Outs of Focus" gives a very useful and intuitive understanding of
not just what will be in focus, but precisely how how much out of focus
foreground and background objects will be. As amazing as that sounds, doing
so requires only dividing two simple numbers. I routinely do so in my head
on every shot where DoF matters. The discussion is at a level appropriate
for practicing photographers rather than physicists. As such, the focus (no
pun) is on geometry as it applies to lenses and light rays, rather than the
physics of light.
"Focusing the View Camera" updates the mathematical treatment and
generalizes the discussion for lens tilt, making it more relevant for large
format photographers, but still very useful and meaningful even if your
optics are firmly fixed with respect to the camera body.
Paul Furman
For comparable DOF, you'd need to stop down the 300mm to the same
diameter opening:
18/5.6 = 3.2mm dia
300/3.2mm = f/93
> Sadly as neither of these is 50mm I can't use them as my entries :-)
You could crop the 18mm shot :-)
Troy Piggins
>> With the wider focal length lens, same aperture, same camera,
>> same focus distance, there is more stuff acceptably in focus.
>
> http://www.luminous-landscape.com/tutorials/dof2.shtml
Maybe you should re-read that. He's moving the setup closer and
closer to the subject so that the subject is the same size as
lenses get wider. His focus distance is different for every
shot, and the perspective changes. I'm not disputing that the
DoF might be the same in that case.
My test was keeping the camera in the same position, changing
lenses, same aperture. The results are that DoF does change, but
the perspective remains essentially the same.
--
Troy Piggins
Troy Piggins
>> http://piggo.com/~troy/images/usenet/091216-dof/35mm-f2_8-crop.jpg
>>
>> With the wider focal length lens, same aperture, same camera,
>> same focus distance, there is more stuff acceptably in focus.
>
> I also got my camera out today and the shots are here:
> http://picasaweb.google.co.uk/csambrook/LensDoFTests#
>
> See my post on the original thread for a painfully technical explanation or
> if you prefer the real world just look at "18mm F5.6 cropped" and "300mm
> F5.6 F5.6 equivalent" to see the fact that the DoF is very different.
>
> Sadly as neither of these is 50mm I can't use them as my entries :-)
Excellent. Another real-world proof. Why do these guys keep
posting links and quoting theory at us when all they have to do
is point their camera at something and try it themselves?
--
Troy Piggins
Paul J Gans
Kodak had an entire series of photographic paperbacks until the
80's or so. They covered all sorts of topics and would be of
general use today.
But as you say, they are gone and there are no replacements.
--
--- Paul J. Gans
John McWilliams
> Kodak had an entire series of photographic paperbacks until the
> 80's or so. They covered all sorts of topics and would be of
> general use today.
>
> But as you say, they are gone and there are no replacements.
I think if you read the whole thread, some have suggested decent
'replacements'.
--
john mcwilliams
Jim Bob
I never read the posts as I only come in now and again and couldn't be
bothered to go through them. Just thought it maybe useful, that's all.
Anyway, different lenses are different. For example, a 135 f/2 shot at 2.8,
will produce totally different results to a 70-200 shot at 135mm/2.8 for the
same subject. This is why some people prefer prime lenses and why the Leica
Noctilux is so desirable for those who are able to afford one.
There is more to DOF than calculations and statistics.
Troy Piggins
> "Troy Piggins" <usene...@piggo.com> wrote in message
> news:2009121...@usenet.piggo.com...
> [---=| Quote block shrinked by t-prot: 17 lines snipped |=---]
>> the perspective remains essentially the same.
>
> bothered to go through them. Just thought it maybe useful, that's all.
You never read the posts you reply to, and you post links that
don't relate directly to the posts you reply to? What's the
point? Nothing personal mate, but if you don't read my post, I'd
rather you not waste your time and mine by not replying at all.
> Anyway, different lenses are different. For example, a 135 f/2 shot at 2.8,
> will produce totally different results to a 70-200 shot at 135mm/2.8 for the
> same subject. This is why some people prefer prime lenses and why the Leica
> Noctilux is so desirable for those who are able to afford one.
Define "totally different results". They'll produce the same
DoF, same perspective, same exposure. Any differences will be
pixel peeping type stuff, unless the quality of one lens is
really, really poor and the other is good to excellent. In which
case you'd be talking about chromatic abberations, sharpness,
detailed stuff. Not fundamentals like DoF.
> There is more to DOF than calculations and statistics.
Correct. There's real world results like taking photos.
--
Troy Piggins
MikeWhy
Because judging from the posted shots, y'all look like you're fumbling in
the dark, trying to stumble upon and reinvent the theory and explain what
you see. Your time is better spent working from an understanding of depth of
field and applying it, proving for yourself that it does work. For these two
shots, the theory explains that DoF relates to aperture *diameter* without
regard to focal length. (Why? Because the cone of confusion relates to
aperture diameter, not aperture fraction of focal length.) It also defines
the exact relationships.
The two shots illustrate that different aperture diameters resulted in
differently rendered backgrounds. If that's all you're after, you can be
done. But does this usefully help your understanding of DoF? Quantifying the
relationship is simple and useful. For example, what f-stops would you need
to render the backgrounds identically with those two lenses? The point isn't
that you would want to do so. Rather, you would have known up front that it
wasn't possible at those focal lengths with the gear you have.
I missed the earlier thread and discussion. I presume the remainder of the
discussion is shooting various focal lenghts while maintaining the same
subject size within the frame. The relationships there also are strictly and
simply linear. You'll find that the background renders identically by
maintaining the same aperture fraction (f/stop) throughout. The theory
"predicts" and explains this very simply and eloquently.
Troy Piggins
For all practical purposes, what matters is understanding the
lenses in my bag, and what depths of field each produce for
different focusing distances. I've done enough shooting,
testing, and reading to know my gear. When I'm taking a shot, I
don't want to be thinking about theory and calculations,
definitions of aperture diameter versus aperture fraction of
focal length. Save that for some written paper or thesis.
For the lenses in my bag, if I take a shot with 2 lenses, same
aperture (f/stop), same focusing distance, the wider lens has a
bigger depth of field. I'm sure the same holds for the lenses in
your bag. That's all we need to know about that.
--
Troy Piggins
Calvin Sambrook
news:hgb4rq$jj6$1...@news.eternal-september.org...
> Calvin Sambrook wrote:
>>
>> I also got my camera out today and the shots are here:
>> http://picasaweb.google.co.uk/csambrook/LensDoFTests#
>> See my post on the original thread for a painfully technical explanation
>> or if you prefer the real world just look at "18mm F5.6 cropped" and
>> "300mm F5.6 F5.6 equivalent" to see the fact that the DoF is very
>> different.
>
> For comparable DOF, you'd need to stop down the 300mm to the same diameter
> opening:
>
> 18/5.6 = 3.2mm dia
> 300/3.2mm = f/93
>
Now that's an interesting interpretation which sounds along the right lines
but I'm not sure I have the toolset to analyse it, either mentally or
practically. Looks like I'll have to drag my camera into work again
tomorrow and take some test shots. I'm buggered if I'm going to start
making F93 irises though, that sounds like a step too far.
>> Sadly as neither of these is 50mm I can't use them as my entries :-)
>
> You could crop the 18mm shot :-)
>
Why didn't I think of that? :-)
MikeWhy
My earlier remarks weren't addressed to you. They were addressed to the
folks taking the effort to understand depth of field. Frankly, it's enitrely
possible to shoot good pictures by rote without ever knowing a single thing
about what the markings on your camera or meter actually mean. But if your
only contribution to a discussion is to point out that continued ignorance
is sufficient for your needs, why bother to post and draw that to attention?
We already know that most folks pointing a camera know very little about
what they're actually doing. Science made that possible, even though you
like to think yourself above it all.
It helps me to know how much detail I can hold in the foreground while still
retaining the detail I want in the distance. Whatever calculations are
needed amount to simple simple arithmetic you learned if you passed the 4th
grade. The papers and thesis have already been written, and re-written. Can
you be bothered to understand a boiled down version of that body of work?
Answer quickly: Will f/16 on a 100mm lens work to resolve 1/4" detail in the
near foreground, 3 feet away, while keeping the steeple across the river in
good focus?
Jim Bob
news:2009121...@usenet.piggo.com...
> You never read the posts you reply to, and you post links that
> don't relate directly to the posts you reply to? What's the
> point? Nothing personal mate, but if you don't read my post, I'd
> rather you not waste your time and mine by not replying at all.
I read your initial post and it sounded familiar to a test that was done
years ago by LL. Hence the link.
>> There is more to DOF than calculations and statistics.
> Correct. There's real world results like taking photos.
Absolutely. Can't disagree with that.
Paul J Gans
Sorry. You are right. I should have.
Calvin Sambrook
>> I also got my camera out today and the shots are here:
>> http://picasaweb.google.co.uk/csambrook/LensDoFTests#
>>
>> See my post on the original thread for a painfully technical explanation
>> or
>> if you prefer the real world just look at "18mm F5.6 cropped" and "300mm
>> >> F5.6 F5.6 equivalent" to see the fact that the DoF is very different.
>
> posting links and quoting theory at us when all they have to do
> is point their camera at something and try it themselves?
>
Both approaches have their place. Having a practical understanding, a "feel
for" if you like, the lenses you use is of course exactly what you need on a
day to day basis. After all you need to be able to concentrate on the art
rather than the science when shooting.
On the other hand a sound understanding of the theory not only helps you to
understand why things are as they are but also to predict how things will
behave and to achieve results which might not be straightforward armed only
with practical experience. The theory also allows you to break a problem
down and isolate a part of it for consideration in a way which is impossible
using empirical means.
Many (most?) good artists, however weird or abstract or apparently
unstructured their work, have a solid background in the theory, only because
of that can they make it look so easy. Miro, for example, might be famous
for making some really strange marks on canvas but if you look at his early
work it is very precise, very technical, very theoretically correct. A more
contemporary example might be Tracey Emin, controversial now in an
is-that-really-art sort of a way but she graduated in fine art and has an MA
in painting from the Royal College of Art.
One of the areas of photography that particularly interests me might be
termed "photography as applied psychology", partly because it's a still
emerging science. When we try to take a "good" photo what we are really
doing is trying to apply our innate, or at least subliminally learned,
knowledge of how the human mind perceives images to get a result. Some of
the basic rules have been known for years and these are captured in the
textbooks but it seems that there are many, deeper, levels as yet not
understood. Good artists seem to have a better practical understanding of
these even though they almost certainly couldn't articulate them.
As an aside I recently heard a very good explanation of usenet trolling as
"applied psychology". The thrust was that the troll is applying his
knowledge of the psychology of the human mind to produce a desired result in
much the same way that an artist does. Different toolset, different desired
result but just as skillful. It almost made me admire good trolls.
Allen
>>>
>> In 1941, when I was 12 years old, I bought a book titled "How to Make
>> Good Pictures" from Kodak for something like 50 cents. (I believe this
>> edition was from 1939 or 1940.) It was a wonderful introduction to
>> photography. Many of the questions I see here (basic lighting, posing,
>> composition, optics, depth of field, shutter speeds, filters and
>> such--and an intro to darkroom work, useless now) are answered in that
>> 70 year old, approximately 150 page book. Looking in bookstores, I don't
>> see anything like that book. What I see now weigh as much as a 4x5
>> Graflex (a conparison from the time when that book was published) and
>> difficult to find answers to your questions. I practically wore the ink
>> off the pages in a year. We need a digital-age equivalent.
>> Allen
>
> Kodak had an entire series of photographic paperbacks until the
> 80's or so. They covered all sorts of topics and would be of
> general use today.
>
> But as you say, they are gone and there are no replacements.
>
I had several binders full of those later Kodak publications, but in
general they covered specific subjects in greater detail. "How to Make
Good Pictures" was an excellent survey that covered many areas of
photography at an elementary level in a volume small enough to carry
around. I bought just about everything that Kodak published back then.
One book that I really liked that I _think_ they published was one by
Jeanette Clute about wildflower photography--some of the most beautiful
wildflower pictures I've ever seen, and taken with a massive 4x5 Graflex.
Troy Piggins
> "Troy Piggins" <usene...@piggo.com> wrote in message
> news:2009121...@usenet.piggo.com...
>>
>> For the lenses in my bag, if I take a shot with 2 lenses, same
>> aperture (f/stop), same focusing distance, the wider lens has a
>> bigger depth of field. I'm sure the same holds for the lenses in
>> your bag. That's all we need to know about that.
>
> My earlier remarks weren't addressed to you. They were addressed to the
> folks taking the effort to understand depth of field. Frankly, it's enitrely
> possible to shoot good pictures by rote without ever knowing a single thing
> about what the markings on your camera or meter actually mean. But if your
> only contribution to a discussion is to point out that continued ignorance
> is sufficient for your needs, why bother to post and draw that to attention?
> We already know that most folks pointing a camera know very little about
> what they're actually doing. Science made that possible, even though you
> like to think yourself above it all.
>
> It helps me to know how much detail I can hold in the foreground while still
> retaining the detail I want in the distance. Whatever calculations are
> needed amount to simple simple arithmetic you learned if you passed the 4th
> grade. The papers and thesis have already been written, and re-written. Can
> you be bothered to understand a boiled down version of that body of work?
>
> Answer quickly: Will f/16 on a 100mm lens work to resolve 1/4" detail in the
> near foreground, 3 feet away, while keeping the steeple across the river in
> good focus?
I'm not being ignorant. I've done the photography courses, I've
read the books, I like understanding the technical side of
things. If anything, I'm more a technical photographer than an
artistic one. I just don't want to get caught up in pedantics
about aperture definitions and so forth. For the average
photographer, dof calculators like the one at
http://www.dofmaster.com/dofjs.html suffice. That's all I'm
saying.
--
Troy Piggins
David J. Littleboy
"Troy Piggins" <usene...@piggo.com> wrote:
>>
>> Answer quickly: Will f/16 on a 100mm lens work to resolve 1/4" detail in
>> the
>> near foreground, 3 feet away, while keeping the steeple across the river
>> in
>> good focus?
> I'm not being ignorant. I've done the photography courses, I've
> read the books, I like understanding the technical side of
> things. If anything, I'm more a technical photographer than an
> artistic one. I just don't want to get caught up in pedantics
> about aperture definitions and so forth. For the average
> photographer, dof calculators like the one at
> http://www.dofmaster.com/dofjs.html suffice. That's all I'm
> saying.
But the DoF calculator doesn't tell you that DoF goes _down_ with the
_square_ of the focal length. That's enormous. It means that a 24mm has four
times the DoF of a 50mm lens and 16 times the DoF of a 100mm lens.
--
David J. Littleboy
Tokyo, Japan
MikeWhy
Fair enough. It was just the terminology that got in the way. I meant only
to say earlier that the diameter of the stepped down aperture opening
determines how DoF is rendered, not the f-number (focal length fraction).
The same f-number at different focal length gives a different stepped down
aperture size. This is why the test shots described earlier had different
DoF.
Give Merklinger's a read if you get a chance. He relates DoF to
distinguishable feature size, often a more useful and meaningful
relationship than hyperfocus distance and CoC. In fact, CoC and DoF scales
are downright misleading if acceptable sharpness relates to object detail
rather than film feature size. (The answer to the above was: yes, f/16 on a
100mm lens will render 1/4" detail in foreground objects for all focus
points beyond 3 ft. For the shot I described, the focus point would have
been on the distant steeple. The foreground would have rendered with the
detail I wanted. f/16 = 100mm / 16 = 6.25mm, just minutely less than the
desired 1/4". See Merklinger's "Ins and Outs of Focus" for details.)
Doug Freese
> Peterson recommended a lot. According to Amazon.com it runs at
> about 160 pages.
I have it and it's a great intro with lots of pictures to demonstate the
basics.
-Doug
Alan Browne
> Really rough real world test to prove to myself recent
> discussions in the SI thread digression about depth of field at
> same aperture but different focal lengths. No, I didn't use a
> tripod. No, the focus point is not exactly the same. But it's
> near enough to express what we're talking about.
>
> This shot was taken at f/2.8 with a 150mm lens:
> http://piggo.com/~troy/images/usenet/091216-dof/150mm-f2_8.jpg
>
> This shot was taken at f/2.8 with a 35mm lens, roughly same
> focusing distance as first shot:
> http://piggo.com/~troy/images/usenet/091216-dof/35mm-f2_8-full.jpg
>
> This was the second shot cropped down to roughly the same field
>
> With the wider focal length lens, same aperture, same camera,
> same focus distance, there is more stuff acceptably in focus.
I repeated your experiment:
Tripod
Lenses: 50mm f/1.7 and 100mm f/2.8 macro (outside macro range)
Conveniently, one is double the others FL.
Target: p18 of http://focustestchart.com/chart.html#ActualChart
And the result is that
http://photo.net/photodb/photo?photo_id=10372793&size=lg
50mm f/1.7 @ f/2.8 - full frame shot
http://photo.net/photodb/photo?photo_id=10372792&size=lg
50mm f/1.7 @ f/2.8 Same photo,
middle crop (simulating 100mm lens FOV).
http://photo.net/photodb/photo?photo_id=10372795&size=lg
100mm f/2.8 @ f/2.8 - full frame shot
Clearly the wider FOV lens, cropped down, even at the same aperture
number gives a deeper field of view.
Similar results to Troy.
MikeWhy
"Alan Browne" <alan....@FreelunchVideotron.ca> wrote in message
news:5a-dnc6QkKRNq7DW...@giganews.com...
Now shoot the same setup with the 100mm at f/5.6. It should match the 50mm
f/2.8 crop.
Alan Browne
Go fer it yourself.
MikeWhy
Done it often enough.
Wilba
>
> I haven't read it, but I see "Understanding Exposure" by Bryan
> Peterson recommended a lot.
Don't bother. IMO it's a coffee table book. It's full of, "I was strolling
down a sun-kissed piazza in Tuscany one fine evening..." -type wank, but
pretty much void of anything technical beyond the trivial. It's out of date
for the digital age (e.g. no expose-to-the-right, live view, etc.), so
people who don't have anything better end up learning obsolete techniques.
Wilba
>
> Not trying to be pedantic; just grasping at some theoretical underpinning
> for
> your observations. It's an article of faith that telephoto lenses have
> lower
> DOF, but the reasoning behind it is seldom explained. I don't pretend to
> be an
> oracle (I'm a computer programmer, not an optical designer), but I know a
> little more physics than the average yokel and am interested in why things
> are
> the way they are.
>
> I haven't yet gotten to the references to circles of confusion in the
> other
> thread. My laziness may have led me into unnecessary repetition, for which
> I
> apologize.
I like the rule of thumb on the page posted in another thread
(http://www.janrik.net/DOFpostings/PM1/DOFInvestigations1.htm) - "DOF
depends only on the angle subtended by the lens, as seen from the subject.
Narrowing the angle gives proportionally larger DOF."
Think of a triangle based on the diameter of the aperture, and the apex at a
point on the plane of focus. He's talking about the angle at the apex, so
when he says "the angle subtended by the lens", to my way of thinking it
would have been better said as "the angle subtended by the aperture".
If that angle is relatively large, you only have to go a short distance from
the plane of focus to get OOF. If the angle is relatively small, you have to
go a long way from the plane of focus to get OOF. That makes perfect sense
but getting your head around specific comparisons take some work. :- )
Wally
<use...@CUTTHISimago.com.au> wrote:
>I like the rule of thumb on the page posted in another thread
>(http://www.janrik.net/DOFpostings/PM1/DOFInvestigations1.htm) - "DOF
>depends only on the angle subtended by the lens, as seen from the subject.
>Narrowing the angle gives proportionally larger DOF."
>
>Think of a triangle based on the diameter of the aperture, and the apex at a
>point on the plane of focus. He's talking about the angle at the apex, so
>when he says "the angle subtended by the lens", to my way of thinking it
>would have been better said as "the angle subtended by the aperture".
>
>If that angle is relatively large, you only have to go a short distance from
>the plane of focus to get OOF. If the angle is relatively small, you have to
>go a long way from the plane of focus to get OOF. That makes perfect sense
>but getting your head around specific comparisons take some work. :- )
Also, that rule works only for a given format. When you compare
different formats all with a "normal" lens, that angle is the same,
but the DOF varies.
Wally
Wilba
See the discussion for case 2 under "Let's see how to apply this rule."
George Kerby
On 3/6/11 11:33 AM, in article dbh7n69l35geer1d9...@4ax.com,
"Ian" <ain...@woeful.com> wrote:
> On Sun, 6 Mar 2011 08:16:23 -0800 (PST), RichA wrote:
>
>> http://forums.dpreview.com/forums/readflat.asp?forum=1041&message=37898881&ch
>> angemode=1
>
>> Notice that one of these people is so brainwashed they even think
>> nothing is made of all metal nowadays? Probably a consummate Walmart
>> shopper.
>
>
> PS I now await the eternal Cyber Vigilante Squad....
> Stand to Battalion Quarter Guard!!
> .
>
Today is the day that The Alamo fell.
Allen
> On Sun, 6 Mar 2011 08:16:23 -0800 (PST), RichA wrote:
>
>> http://forums.dpreview.com/forums/readflat.asp?forum=1041&message=37898881&changemode=1
>
>> Notice that one of these people is so brainwashed they even think
>> nothing is made of all metal nowadays? Probably a consummate Walmart
>> shopper.
>
>
> .... the alleged plastic versus metal debate is carried on in one head
> (excluding arse lickers, agitator Trolls and assorted nuts.)
>
> Ian.
>
<snip>
I have a suggestion for RichA. Replace all your electric plugs with
all-metal ones. Then go all through your house, plugging them in one by
one--or until you get the idea through your thick skull that plastic has
its uses.
Allen
Savageduck
> In article <o8idnSA7fNOxZO7Q...@giganews.com>,
> Another way for home testing use (do not try this at home)
>
> A Glock 10mm pistol is made almost entirely of plastic.
Not exactly.
> The chamber pressure of a 10mm cartridge with a 155 grain bullet is
> 23,000 psi (yes, that's twenty three thousand pounds per square inch)
...and all of that is contained within an all steel barrel & chamber.
That in turn is covered by a steel alloy slide.
80% of the weight of any Glock pistol is the metal components (+ ammo).
Only the frame & magazines are very tough, light weight poly-carbonate.
I have a 23 year old Glock 23, which is tough as nails and functions
flawlessly. However as a concealed carry weapon the double stack
magazine makes it kind of lumpy, and for any shooter, the trigger is
not the greatest. My weapon of choice for carry is my Kimber Custom PRO
CDP II in 45 ACP. Great for carry, great trigger and it can do the job.
< http://homepage.mac.com/lco/filechute/DNC_7557Aw.jpg >
< http://homepage.mac.com/lco/filechute/Kimber%26Targetw.jpg >
> Now, someone who believes all plastic is inferior to all metal would
> have no problem performing this test (do not try this test):
>
> Load up a Glock 10mm ...........
You really shouldn't play with plastic man that way, in Canada he only
has access to Para Ordinance handguns.
--
Regards,
Savageduck
Rich
> On 2011-03-06 20:17:51 -0800, shiva das <s...@nataraja.invalid> said:
>
>
>
> > In article <o8idnSA7fNOxZO7QnZ2dnUVZ5qOdn...@giganews.com>,
> > Allen <all...@austin.rr.com> wrote:
>
> >> On 3/6/2011 11:33 AM, Ian wrote:
> >>> On Sun, 6 Mar 2011 08:16:23 -0800 (PST), RichA wrote:
>
I've used a Glock. None of the parts that experience pressure or wear
in it are plastic.
Rich
> On 3/6/2011 11:33 AM, Ian wrote:> On Sun, 6 Mar 2011 08:16:23 -0800 (PST), RichA wrote:
>
>
> >> Notice that one of these people is so brainwashed they even think
> >> nothing is made of all metal nowadays? Probably a consummate Walmart
> >> shopper.
>
> > We all know who the "Eternal Plastic" is..........
>
> > .... the alleged plastic versus metal debate is carried on in one head
> > (excluding arse lickers, agitator Trolls and assorted nuts.)
>
> > Ian.
>
> <snip>
> I have a suggestion for RichA. Replace all your electric plugs with
> all-metal ones. Then go all through your house, plugging them in one by
> one--or until you get the idea through your thick skull that plastic has
> its uses.
> Allen
Poor, poor desperate plastic whore. Grasping at straws, going off on
HUGE tangents (durability to conductivity!! MORON!) so why not just
say, UNCLE?
Eric Stevens
wrote:
>I've used a Glock. None of the parts that experience pressure or wear
>in it are plastic.
I've used many Nikons and a number of Canons. None of the parts that
experience pressure or wear in them are plastic.
Regards,
Eric Stevens
Michael
> Really rough real world test to prove to myself recent
> discussions in the SI thread digression about depth of field at
> same aperture but different focal lengths. No, I didn't use a
> tripod. No, the focus point is not exactly the same. But it's
> near enough to express what we're talking about.
>
> This shot was taken at f/2.8 with a 150mm lens:
> http://piggo.com/~troy/images/usenet/091216-dof/150mm-f2_8.jpg
>
> This shot was taken at f/2.8 with a 35mm lens, roughly same
> focusing distance as first shot:
> http://piggo.com/~troy/images/usenet/091216-dof/35mm-f2_8-full.jpg
>
> This was the second shot cropped down to roughly the same field
> of view as the 150mm lens shot:
> http://piggo.com/~troy/images/usenet/091216-dof/35mm-f2_8-crop.jpg
>
> With the wider focal length lens, same aperture, same camera,
> same focus distance, there is more stuff acceptably in focus.
Yes, an empirical experiment is nice, but science tells you the answer
more quickly. At any given "f stop" the lens, whatever its focal
length, passes the same amount of light as any other at that "f stop."
So you can meter without regard to your lens, if the exposure is 125th
of a second at f/5.6 use any lens set to f/5.6 at 125th and you'll get
the exposure. But "f stop" means "focal length divided by...." and fill
in the number. The number is the number of the "f stop." A 150mm lens
at f/2 has an aperture of 75mm. An 80 mm lens at f/2 has an aperture of
40mm. A 20mm lens at that f stop has an aperture of 10mm. All pass the
same light because the amount of light passed is a function of the
aperture size (absolute) and focal length. But light waves have a
physical size. Depth of field/depth of focus relates to the absolute
size of the aperture as it impacts the wavelength of light. So you get
a deeper depth of field with a smaller absolute opening. And since
f/5.6 has a small absolute opening on a wide angle lens than it does on
a telephoto, the wide angle has the greater depth of field. It's just
optics. Not rocket science.
--
Michael
Troy Piggins
> On 2009-12-15 17:30:30 -0500, Troy Piggins said:
>
>> of view as the 150mm lens shot:
>> http://piggo.com/~troy/images/usenet/091216-dof/35mm-f2_8-crop.jpg
>>
>> With the wider focal length lens, same aperture, same camera,
>> same focus distance, there is more stuff acceptably in focus.
>
> Yes, an empirical experiment is nice, but science tells you the answer
> more quickly. At any given "f stop" the lens, whatever its focal
> length, passes the same amount of light as any other at that "f stop."
> So you can meter without regard to your lens, if the exposure is 125th
> of a second at f/5.6 use any lens set to f/5.6 at 125th and you'll get
> at f/2 has an aperture of 75mm. An 80 mm lens at f/2 has an aperture of
> 40mm. A 20mm lens at that f stop has an aperture of 10mm. All pass the
> same light because the amount of light passed is a function of the
> aperture size (absolute) and focal length. But light waves have a
> physical size. Depth of field/depth of focus relates to the absolute
> size of the aperture as it impacts the wavelength of light. So you get
> a deeper depth of field with a smaller absolute opening. And since
> f/5.6 has a small absolute opening on a wide angle lens than it does on
> a telephoto, the wide angle has the greater depth of field. It's just
> optics. Not rocket science.
Holy thread resurrections, Batman. You're replying to a post of
mine from December 2009. Cool.
I know the science. If you'll note the first paragraph I mention
there was a recent discussion elsewhere in that group about this,
but I started a new thread as the other one was getting
off-topic.
My empirical experiment was to "prove" the "science" in a very
loose and informal manner.
Thanks.
--
Troy Piggins
Eric Stevens
wrote:
>Troy Piggins wrote:
>> * Wally wrote :
>>> On Wed, 16 Dec 2009 08:30:30 +1000, Troy Piggins
>>> <usene...@piggo.com> wrote:
>>>
>>> [---=| Quote block shrinked by t-prot: 14 lines snipped |=---]
>>>> of view as the 150mm lens shot:
>>>> http://piggo.com/~troy/images/usenet/091216-dof/35mm-f2_8-crop.jpg
>>>>
>>>> With the wider focal length lens, same aperture, same camera,
>>>> same focus distance, there is more stuff acceptably in focus.
>>> First of all, good for you for doing tests. You will learn real
>>> things. Experiments beat theory.
>>>
>>> Secondly, you are right, shooting with a wide angle lens and then
>>> cropping to the same image size will give you much better DOF.
>>>
>>> But thirdly, if you move in with the wide angle to get the same image
>>> size, then the DOF will be the same.
>>>
>>> Except that it might not be -- I suspect the latter case will show the
>>> long lens to give better DOF. That's because the exit pupil is
>>> usually smaller than expected for tele lenses. Look at the front of
>>> the lens, then at the back. Do the apertures look the same size? It
>>> will probably look smaller from the back, and that should give better
>>> DOF.
>>
>> The perspective is different too. That's not what I was trying
>> to test. As to whether the DoF will be the same, don't know and
>> don't care at the moment. I was trying to illustrate a point
>> raised in another thread.
>>
>> I know if you move closer, ie reduce focus distance, the DoF
>> narrows as well. So it makes sense that at some point if you
>> take a shot with a longer lens, and another shot closer to the
>> subject with the same aperture, you could end up with
>> similar/same DoF. But the perspectives will be different, and
>> the field of view may or may not be the same.
>>
>In 1941, when I was 12 years old, I bought a book titled "How to Make
>Good Pictures" from Kodak for something like 50 cents. (I believe this
>edition was from 1939 or 1940.) It was a wonderful introduction to
>photography. Many of the questions I see here (basic lighting, posing,
>composition, optics, depth of field, shutter speeds, filters and
>such--and an intro to darkroom work, useless now) are answered in that
>70 year old, approximately 150 page book. Looking in bookstores, I don't
>see anything like that book. What I see now weigh as much as a 4x5
>Graflex (a conparison from the time when that book was published) and
>difficult to find answers to your questions. I practically wore the ink
>off the pages in a year. We need a digital-age equivalent.
>Allen
I agree. My introduction was via the 'Ilford Encyclopaedia of
Photography'. I don't know what happened to my copy but I've been
fruitlessly hunting for an eqivalent for the last several years.
Regards,
Eric Stevens
newshound
"Eric Stevens" <eric.s...@sum.co.nz> wrote in message
news:r5ifn69ijmvokltaj...@4ax.com...
Well here is the Kodak one.....
tony cooper
>>Good Pictures" from Kodak for something like 50 cents. (I believe this
>>edition was from 1939 or 1940.) It was a wonderful introduction to
>>photography. Many of the questions I see here (basic lighting, posing,
>>composition, optics, depth of field, shutter speeds, filters and
>>such--and an intro to darkroom work, useless now) are answered in that
>>70 year old, approximately 150 page book. Looking in bookstores, I don't
>>see anything like that book.
I have that book. Here's a scan of the cover:
http://i48.photobucket.com/albums/f244/cooper213/kodak.jpg
My copy does not have a publication date. All it says is
"Twenty-Sixth Edition, Revised". Judging by the clothing styles of
the people in the photos in the book, it dates back to the 40s.
I'm sure there are clues in the text about the book's date. For
example, it has to date before 1959 since Verichrome is discussed.
The chapter on camera choice lists the Brownie Reflex, the Speed
Graphic, and the Kodak Ektra, Bantam, and Vigilant.
I was thinking of offering it as a prize for "The Best Siskerized
Photo" contest.
--
Tony Cooper - Orlando, Florida
Savageduck
A little searching shows that the 'Ilford Encyclopaedia of Photography'
first published in 1890 by Britannica Works Co. became the "Ilford
Manual of photography".
A check with Amazon shows it somewhat available;
<
http://www.amazon.com/Ilford-Manual-Photography-George-Brown/dp/1444657259/ref=sr_1_1?s=books&ie=UTF8&qid=1299700789&sr=1-1
>
or
< http://thurly.net/111a >
They show other used editions dating from 1897;
<
http://www.amazon.com/s/ref=nb_sb_ss_c_1_28?url=search-alias%3Dstripbooks&field-keywords=ilford+manual+of+photography&sprefix=ilford+manual+of+photography
>
or
< http://thurly.net/1119 >
--
Regards,
Savageduck
Peter N
>
My FM had a lot of plastic in those parts.
--
from my Droid
Eric Stevens
wrote:
There certainly was a lot of plastic in the FM but as far as I can
recall, all the most highly stressed parts were metal.
Regards,
Eric Stevens
PeterN
IIRC
The film take up mechanism was all plastic. A broken plastic cam, which
was not worth repairing did it in.
The body is in storage, for no sound reason.
--
Peter
Eric Stevens
That surprises me. I would not have thought that was highly stressed.
Was the cause of the fracture identified?
Regards,
Eric Stevens
Eric Stevens
That looks like the one.
Regards,
Eric Stevens
Peter N
No. I was told that it could be too much use of the motor. But i just
charged it up to experience.
--
from my Droid
Eric Stevens
wrote:
Aah - you had a motor drive. Mine was manual.
That puts things in a slightly different perspective. Still, I
wouldn't have expected that to just break. I suspect there may have
been signs of preliminary wear.
Regards,
Eric Stevens
Peter N
<eric.s...@sum.co.nz> wrote:
> On Tue, 15 Mar 2011 20:43:27 -0400, Peter N <fa...@fakeemail.com>
just
> >charged it up to experience.
> Aah - you had a motor drive. Mine was manual.
> That puts things in a slightly different perspective. Still, I
> wouldn't have expected that to just break. I suspect there may have
> been signs of preliminary wear.
If there was I did not notice. To me a camera is just a tool or a
thing.
--
from my Droid