Resolution 6x7 cm vs. 4x5 inch
John
Hi!
I'm using an Arca Swiss F-line and 4x5 inch film. Sometimes I get asked how
much better this is than medium format 6x7 cm. I will not focus on any of
the advantages with mechanical settings etc. that the F-line has over most
MF cameras but rather on the film quality:
1. 4x5" is x % bigger than 6x7 cm. Does it contain equally much
information?
2. Some say that MF film is better because it is thinner and has less
diffraction - what are the actual datas describing this phenomena?
3. What is the accepted usable surfaces on each resp. film?
4. Are there any sites that show real tests and comparisons between the two
formats.
One often heard comment is, "well, medium format is quite good now, the
films have become so much better....". Hasn't film on 4x5" got equally much
better?
Comments please!
I shoot mainly architecture.
Best regards from Sweden!
John
Richard Knoppow
"John" <jsa...@hotmail.com> wrote:
Where the same emulsion is used for both roll and sheet films the
resolution is the same. Coating thickness is about the same on both
types, its the support which is a lot thicker on sheet film. This is
of no consequence for scattering or loss of resolution.
Some films do have thinner emulsions, Technical Pan, for example,
but again, the emulsion thickness is the same regardless of the
format.
Film has gotten good enough so there isn't a big jump in quality
between 6cm x 6cm and 4x5 as there was in the past. There is still a
big jump between 35mm and 6x6 but there used to be another just about
as great when going to 4x5, no longer, at least for reasonable size
prints. You can still see the difference for prints larger than about
11x14 its just not a stunning as it was many years ago.
---
Richard Knoppow
Los Angeles, Ca.
dick...@ix.netcom.com
P.Groepper
I've defined my own way to compare the quality:
You can enlarge any neg about 3.5 times without visible loss of quality
(sharpness, saturation, tonal differentiation) to the naked eye. For 6x7
this means a print of about 21x25 cm and for 4x5 a print of about 35x44
cm. Both have the same quality. Conclusion: If you need a print larger
than about 20x25 and with 'optimum quality', go to 4x5. If you need to
go even beyond 35x44 (again with 'optimum quality'), go to 5x7 or even
8x10 or beyond.
This is applicable for prints, you want to hold in your hand or look at
from as close as you wish with naked eye. Prints or projected slides
located meters away from your eyes may be allowed less quality.
One may argue about the mag.factor of 3.5, but I don't care to much
about such details. Anything wrong with this approach?
Peter
--
Christopher M. Perez
John wrote:
> Sometimes I get asked how
> much better [4x5] is than medium format 6x7 cm.
>
> 1. 4x5" is x % bigger than 6x7 cm. Does it contain equally much
> information?
4x5inches gives 20 square inches of surface area.
6x7cm gives 6.5 square inches of surface area.
You get _three_ times the surface area by using 4x5. I'd say you get
significantly greater information on film by using 4x5.
> 2. Some say that MF film is better because it is thinner and has less
> diffraction - what are the actual datas describing this phenomena?
I've not found any and would be v.interested if someone could come up with a
pointer to this information.
> 3. What is the accepted usable surfaces on each resp. film?
See first comment.
> 4. Are there any sites that show real tests and comparisons between the two
> formats... One often heard comment is, "well, medium format is quite good now,
> the
> films have become so much better....". Hasn't film on 4x5" got equally much
> better?
>
We know that the best film will resolve in a 1:6 contrast ratio image is right
at 100 lines/mm. This holds true regardless of whether it's 120/220 (thin-base
film) or 4x5. I understand that this holds true between certain color films and
the latest fine-grain B&W. So, no, there will be v.little or no difference
between the two (thin or thick-base) film's ability to resolve.
Kerry Thalmann and I have been testing various lenses (and I will be testing a
few 6x6/6x9 lenses in the near future). You can see the latest results at:
http://www.hevanet.com/cperez/testing.html I am making a short leap of faith in
saying: You will find no practical difference between a well made lens for use
in 4x5 or 6x6/6x7/6x9. The primary difference being the compromises required to
fit a mirror between a lens and the film as needed by many 6x6/6x7/6x9 cameras
these days. This may well influence the quality of lenses in medium format
(tilting in favor of well-corrected 4x5 lenses! - see my comments on the
practical results seen in testing Schneider's new lens designs at:
http://www/hevanet.com/cperez/kit.html ).
The "real" differences between these formats may well end up being just how much
more magnification is required to enlarge 6x7 to the same final print size. The
grain structure of an enlarged 6x7 image will be at least _twice_ the size of a
4x5 image printed to same final print size!!!
Only you will be able to tell us if this difference is important or not.
Personally: I'd suggest shooting 8x10 transparencies and just call it a day...
the quality _is_ visible... :-)
- Chris
Scot W. Perry
I'll throw something new into your equations.
It is my opinion that the actual enlarging process is the main culprit
in quality loss. Mainly due to the projection of the image to produce
larger sizes. As I deal mainly in the digital field I have found you
can get phenomenal quality enlargements from even 35mm when you scan
and digitaly print verses traditional photo enlargement. In fact we
scanned a 35mm slide and made a 48 x 72 inch print yesterday that even
a 6x7 traditionaly enlarged could not have matched. Of course a
scanned larger format transparency would have unquestionably produced
an even more impressive print.
Scot Perry
Artworx
digital imaging services and supplies
Mike McDonald
In article <358FD554...@vnd.tek.com>,
"Christopher M. Perez" <chri...@vnd.tek.com> writes:
> John wrote:
>
>> Sometimes I get asked how
>> much better [4x5] is than medium format 6x7 cm.
>>
>> 1. 4x5" is x % bigger than 6x7 cm. Does it contain equally much
>> information?
>
> 4x5inches gives 20 square inches of surface area.
>
> 6x7cm gives 6.5 square inches of surface area.
>
> You get _three_ times the surface area by using 4x5. I'd say you get
> significantly greater information on film by using 4x5.
It's linear size that counts. Area is just a by product of the linear
difference. In this case, 4x5 is about 2x better than 6x7.
>
>> 4. Are there any sites that show real tests and comparisons between the two
>> formats... One often heard comment is, "well, medium format is quite good now,
>> the
>> films have become so much better....". Hasn't film on 4x5" got equally much
>> better?
>>
>
> We know that the best film will resolve in a 1:6 contrast ratio image is right
> at 100 lines/mm.
Let's use the 100 lines/mm for an example. At that resolution, a 6x6
negative has 6000 lines across. A 4x5 negative has 10160 lines across. (This
is ideal conditions, not taking lenses or defraction into account.) If a human
can visually resolve X lines/mm in a print, then the maximum print without
visible artifacts would be 6000/X and 10160/X mm respectively. Pick an X that
you think you can resolve in a print and that'll tell you the absolutely
largest print you can make from your negative. In practise, you won't be able
to do that well, due to errors that creep into the system.
Mike McDonald
mik...@mikemac.com
Kerry Thalmann
P.Groepper wrote:
> One may argue about the mag.factor of 3.5, but I don't care to much
> about such details. Anything wrong with this approach?
Hi Peter,
I don't wish to argue, but I am curious as to what you think limits the
enlargement factor to 3.5. Is it on-film resolution or visible grain?
Based on the lens tests Chris Perez and I have been conducting, and
several articles I have read on the subject (and practical experience)
it would appear that on-film resolution would permit a much larger
enlargement factor. Using a modern fine grained film (T-max 100 for
black and white or Fuji Velvia for color) and the very best modern lens,
you should be able to enlarge by a factor of 10 before the human eye can
detect any loss of sharpness in the final print when viewed from 1/2
meter (a very close distance to view a 40"x50" print). This does not
take into account the effect of visible grain in the final print. I
have not yet determined what the limit is on enlargement before I find
the grain distracting. Of course, this all depends on the film used,
the viewing distance (if the print is otherwise sharp, the eye becomes
much more forgiving of grain as the viewing distance is increased) and
the eye of the viewer. One article I did read that compared the effects
of both grain and on film resolution determined it was indeed the grain
that limited the enlargement factor (to 2.75 based on his results) even
though the on film resolution in his tests yeilded an enlargement factor
>9.
So, we keep hearing the argument that modern films and lenses are so
good that there is no longer a need to shoot large format (of course, I
don't buy into that argument, and it is always presented by those who
shoot in smaller formats), but it indeed looks like we need even finer
grained films to get a higher degree of enlargement. Modern lenses (and
for that matter even many 50 year old large format lenses) are capable
of achieving very high on-film resolutions. In the end, it looks like
the grain structure of the film may be the limiting factor in
determining the maximum enlargement. Of course, this grain structure is
a function of the emulsion and will be the same for any emulsion
regardless of the format.
Finally, the normal viewing distance increases as the size of the print
increases. Grain that is objectionable in an 8"x10" print at 1/2 meter
may be unnoticed in a 40"x50" viewed from across the room. This is the
one relationship I have yet to quantify (I still need a formula for the
effects of visible grain as a function of viewing distance). I have
made prints up to 30"x40" from 4x5 with acceptable (for me) results, and
I regularly make 24"x30" prints. This relationship between visible
grain and viewing distance is one more factor that favors the larger
formats. Assuming the same emulsions and a constant enlargement factor,
the final print size, and thus the normal viewing distance increases as
direct function of the film size. So, even though the enlargement
factor is similar, at normal viewing distances, a 20"x24" print from a
4x5 original would appear less grainy than an 11"x14" print from 6x7cm.
This also explains why, in a gallery setting, I can always tell from
across the room, which 20"x24" prints were made from medium format and
which from large format. It is not the lack of sharpness of the film or
lenses, it is simply the effects of the film grain. The grain is just
much more obvious, to my eye, in the prints made from medium format
originals.
Kerry
--
Kerry L. Thalmann Large Format Images of Nature
A Few of My Images Online at: http://home.att.net/~k.thalmann/
Richard Knoppow
Kerry Thalmann <K.Tha...@worldnet.att.net> wrote:
There are a number of conflicting, or at least not very intuitive,
factors here.
First, the resolution of the system is going to be considerably less
than the resolution of either film or lens. At least in medium format
and small format the resolutions of film and lens will be somewhat
similar. When lens and film have equal resolution the resulting
system resolution is either 1/2 or 2^1/2, depending on how you
calculate it.
The resolution numbers being stated here are all high-contrast
numbers (1000:1). Resolution of both film and lenses varies with
contrast. In film, its due to scattering and some other factors, in
lenses its due to residual spherical aberration and other aberrations.
For low-contrast targets, perhaps 10:1, resolution numbers for both
film and lenses will be much lower, perhaps half the high-contrast
numbers.
Adding to this the loss in enlarging, which is not straight forward
to calculate, results in a surprizingly low number by the time the
image gets to the paper.
Larger formats to some degree reduce the contribution of both the
film and the printing process to this degradation of resolution. The
lenses may have less resolution due both to greater residual
aberration in most large-format lenses (may not be true of the very
latest crop) and to the necessity of stopping down for reasonable
depth of field.
Larger negatives also have the advantage of more grains to carry the
image so have better tonal reproduction than smaller ones. This is
very apparent when comparing 35mm to anything larger but less so when
the smaller is larger than 35mm.
Perceived sharpness is controlled more by other factors than
resolution. Edge contrast is an important one. The eye also tends to
interpret contrast as sharpness, even when the actual detail
reproduced is poor.
There is probably an optimum size negative for a given print size,
it will be different for different film and perhaps also other
factors. I have no idea how to calculate such a thing but visual
examination gives some clues.
John Sparks
>> One may argue about the mag.factor of 3.5, but I don't care to much
>> about such details. Anything wrong with this approach?
>I don't wish to argue, but I am curious as to what you think limits the
>enlargement factor to 3.5. Is it on-film resolution or visible grain?
I don't know where Peter came up with 3.5 for the factor, but it agrees
pretty well with my observations (at least for prints from B&W, prints
from color allow larger enlargements before I notice differences between
formats). I'm not sure if it's exactly a constant. I think the max
enlargment factor without ANY loss of quality is smaller for larger
negatives (maybe 3X for 8x10, 3.5X for 4x5, maybe 4.5x for 2 1/4" and
5.5X for 35mm). I think this is because lens quality improves slightly with
smaller negatives and film plane accuraccy improves more substantially
so that things don't improve quite as much as the linear film dimension
increase would predict.
I find that 16x20 prints from 4x5 (~4X prints) look noticably different
from 16x20 prints from 8x10 in most cases. It's definately not grain
since I can't see grain in either, at least from fine grain films like
Tmax. I doubt it's resolution either (at least not resolution measured
by line pairs/mm) since I don't think my eyes can resolve more what you
get from a 4X enlargement.
I think there is something beyond what the resolution number tell you.
Your eyes can detect some of the high-frequency stuff beyond the lp/mm
limit. The numbers I've seen for resolution limits in a print that can
be seen with the naked eye are about 8 or 10 lp/mm. This seems to match
what I can see when looking at a resolution chart with my eyes.
However, I think you can tell the difference between a sharp square wave
10 lp/mm and a fuzzy, noisy 10 lp/mm that you get at the film/lens
resolution limit. To capture this difference, you need a lot more than
10 lp/mm.
From the difference I can see in 16x20 prints (a 2X print from 8x10 or a
4X print from 4x5) or even in 11x14 prints, (a 1.4X or 3X) though this
is a much more subtle difference, I'd guess that you need somewhere
around 30 lp/mm in the print to get the maximum quality that you can see
with a naked eye. I know I want to put my eye right up next to a print
(call this 10"-20"), reguardless of print size. Unless there is a
barrier that prevents close observation of large prints, I find most
people look at prints from about the same distance no matter what size
the print is. If you keep your eye about the print diagonal or more
from the print (which explains why billboards made from 35mm can look
sharp when you drive by them many yards away), I don't see any problems
with any size prints from 4x5, but I don't (and I don't see others)
looking at prints that way.
John Sparks
Don Norris
I believe that the optimum size negative for an 8X10 print is 8X10. I have
yet to see the tonality in an enlargement that comes close to a contact
print. Not that I don't enlarge - I've made 4' X 8' prints from 35mm
negatives, you do what you have to, but it's the contact prints from 8X10
negatives that I really love.
--
James Chow
> You can enlarge any neg about 3.5 times without visible loss of quality
> (sharpness, saturation, tonal differentiation) to the naked eye. For 6x7
> this means a print of about 21x25 cm and for 4x5 a print of about 35x44
> cm. Both have the same quality. Conclusion: If you need a print larger
> than about 20x25 and with 'optimum quality', go to 4x5. If you need to
> go even beyond 35x44 (again with 'optimum quality'), go to 5x7 or even
> 8x10 or beyond.
For framing 6x6, I usually go to 16x16 inches, so that's about 7x. I don't
crop and retain the square. For 4x5, 7x is 28x35". If you're going to mat
and frame
the photos properly, galleries will usually recommend at least a 2" mat border,
ideally more like 4" to draw attention to the photo. OTOH, if you're using no
mat, then a larger print is suitable.
--Jim
P.Groepper
Kerry, thanks for your good post.
Kerry Thalmann wrote:
> I don't wish to argue, but I am curious as to what you think
> limits the enlargement factor to 3.5. Is it on-film resolution
> or visible grain? Based on the lens tests Chris Perez and I have
> been conducting, and several articles I have read on the subject
> (and practical experience) it would appear that on-film resolution
> would permit a much larger enlargement factor....rest snipped
the factor of 3.5 was based on color prints from a lab, thus on my own
very practical circumstances and experiences. As soon, as these prints
were significantly larger than, say, 3 to 4 times magnification
(therefore "3.5"), I could either see grain, unsharpness, lack of colour
saturation or other things. But I also tried to make clear, that this
factor relates to viewing photos with the naked eye. And that can mean,
in some cases (I should say, according to MY habbits), to inspect
details, even on a larger print, from a distance of only 15 cm. Going
back to 1/2 meter definitely changes the situation and would even match
quite well your and my numbers ( >9 times vs. 3.5 ).
But the bottomline of my comment was: whatever you choose, the larger
format is better, as a rule of thumb, by the ratio of it's linear
dimensions. Thus, an 8x10 is double as good, as a 4x5, not taking into
account problems related to film flatness, film thickness, lens
performance etc.. And "double as good" simply shall be understood as
"you can approximately enlarge it twice as much with approximately the
same quality".
And for me (!) such rule of thumb is sufficient, because I don't want to
enter into discussion about WHEN grain starts to become too visible,
WHEN colour saturation is no longer satisfying etc.. It is a bit like
with the performance of HiFi music equipment. And eventually I'd still
prefer "good" music from a bad "radio" than vice versa. Quality in the
frame we are discussing, is definitely not a binary yes/no thing.
Peter
John
OK. Thanks for all good answers to my res.questions.
On thing that sort of got lost in this whole discussion was my question:
1. The fact that the 6x7 film is thinner than 4x5" film, how exactly does
that influence quality (resolution, other characteristics)?
2. Will the thickness play a different role whe scanning compared to making
traditional enlargements?
3. What will the difference in thickness do? Making a small light dot on a
slide have halos around it? Or what?
4. Decreasing high end frequency response or low end or what?
Having tested myself on a flatbed scanner is difficult because the smaller
surface of the 6x7 cm revelas the scanners limitations rathers than the 6x7
limitations. Certainly, using a tabletop standard HP scanner with 4x5"
produces far better results than scanning 6x7cm but that is to a large
extent because of my HP ScanJet scanner.
But of course, just in term of grainyness, 4x5 is better. Of course it is.
Let's not get to philosophical about how much we can enlarge etc. (although
interesting issues) but rather stay close to the issue about how *filmbase
thickness affects quality*.
By the way - just bought the binocular viewer to my Arca Swiss F-line -
what a relief from the darkcloth!! So much more pleasant to work with the
camera now! I highly recommend it.
Best regards from Sweden!
John
Mike McDonald <mik...@mikemac.com> skrev i inlägg
<vPRj1.11769$JX6.8...@news.teleport.com>...
Tom Rittenhouse
Mike McDonald (mik...@mikemac.com) wrote:
|
| Let's use the 100 lines/mm for an example. At that resolution, a 6x6
|negative has 6000 lines across. A 4x5 negative has 10160 lines across. (This
|is ideal conditions, not taking lenses or defraction into account.) If a human
|
numbers come out to 5600 vs. 12000, so your error factor is
rather high.
--
Graywolf (Tom Rittenhouse)
---------------------------------------------------------------
Mark Bergman
I'm not really sure if film thickness plays any part in this. The emulsion
thickness does. I'm don't think 4x5 or 8x10 emulsion thickness is any
different than 2x3. You get into so many different factors (such as
anti-halation backing, color/B&W/slide) that I doubt very much if you can make
any comparison between a 120 film and 4x5 unless you talk speciffically one
type of film. Even then I doubt if it makes a really difference.
I shoot 2x3 on a Horseman 970 and 4x5 on a monorail. The 2x3 usually wins just
because it has better lenses. However it is real subjective on what I'm
shooting and a whole lot of other factors. I do 90% of my shots on T-Max.
John wrote:
> > Let's use the 100 lines/mm for an example. At that resolution, a 6x6
> > negative has 6000 lines across. A 4x5 negative has 10160 lines across.
> (This
> > is ideal conditions, not taking lenses or defraction into account.) If a
> human
Kerry Thalmann
Richard Knoppow wrote:
> There are a number of conflicting, or at least not very intuitive,
> factors here.
Hi Richard,
Yes, in fact there are so many different variables that I don't think it
is possible to come up with one answer (or even a set of universal
equations) to this question.
> First, the resolution of the system is going to be considerably less
> than the resolution of either film or lens. At least in medium format
> and small format the resolutions of film and lens will be somewhat
> similar. When lens and film have equal resolution the resulting
> system resolution is either 1/2 or 2^1/2, depending on how you
> calculate it.
Actually, some of the aerial resolution numbers I have seen for the best
modern 35mm lenses at wide stops are for higher than the capability of
any film made. In fact, the best of the current large format lenses are
getting close to matching the limits of the film and also close the the
theoretical diffraction limits at normal working stops. But yes, it is
the overall system resolution that is important, and it will be lower
than both the indivdual components.
> The resolution numbers being stated here are all high-contrast
> numbers (1000:1). Resolution of both film and lenses varies with
> contrast. In film, its due to scattering and some other factors, in
> lenses its due to residual spherical aberration and other aberrations.
> For low-contrast targets, perhaps 10:1, resolution numbers for both
> film and lenses will be much lower, perhaps half the high-contrast
> numbers.
Yes, contrast definately plays a big part in the final on-film
resolution. Also, test charts are two dimensional. Most subjects of
general interest in the real world are not. Complex three dimensional
subjects often require stopping down to f22, f32 or occasionally beyond
to achieve the desired depth of field. Diffraction plays a definite
roll in limiting resolution at small stops. Along with other variables
(minute focusing errors, film plane position and flatness, wind induced
camera or subject movement, etc.) this means that when shooting normal
contrast, three dimensional subjects under field conditions, the
resolution will always be considerably lower than the test results. In
fact, the test results should be considered best case, not typical,
results.
> Adding to this the loss in enlarging, which is not straight forward
> to calculate, results in a surprizingly low number by the time the
> image gets to the paper.
Yes, and don't forget the resolving capability of the paper itself.
> Larger formats to some degree reduce the contribution of both the
> film and the printing process to this degradation of resolution. The
> lenses may have less resolution due both to greater residual
> aberration in most large-format lenses (may not be true of the very
> latest crop) and to the necessity of stopping down for reasonable
> depth of field.
> Larger negatives also have the advantage of more grains to carry the
> image so have better tonal reproduction than smaller ones. This is
> very apparent when comparing 35mm to anything larger but less so when
> the smaller is larger than 35mm.
Agreed.
> Perceived sharpness is controlled more by other factors than
> resolution. Edge contrast is an important one. The eye also tends to
> interpret contrast as sharpness, even when the actual detail
> reproduced is poor.
This is one very important factor not accounted for in lens testing.
> There is probably an optimum size negative for a given print size,
> it will be different for different film and perhaps also other
> factors. I have no idea how to calculate such a thing but visual
> examination gives some clues.
In the end, I think visual examination is the only way to determine what
is and is not acceptable. Of course, the definition of acceptable will
vary from person to person as well (and this is why I think it is
impossible to come up with one correct answer to this question).
Kerry Thalmann
John Sparks wrote:
> I think there is something beyond what the resolution number tell you.
> Your eyes can detect some of the high-frequency stuff beyond the lp/mm
> limit. The numbers I've seen for resolution limits in a print that can
> be seen with the naked eye are about 8 or 10 lp/mm. This seems to match
> what I can see when looking at a resolution chart with my eyes.
> However, I think you can tell the difference between a sharp square wave
> 10 lp/mm and a fuzzy, noisy 10 lp/mm that you get at the film/lens
> resolution limit. To capture this difference, you need a lot more than
> 10 lp/mm.
Hi John,
I don't think what you are describing is really a function of on film
resolution (as measured in lp/mm). As Richard pointed out, edge
contrast has a significant impact on PERCEIVED sharpness. Also, subtle
tonal differences seem to give prints made from larger negatives a
smoother, more seamless look. Even though you don't notice the grain, I
think the finer grain size in a print made from a large negative
contributes a lot to the apparent smooth tonal graduations.
> From the difference I can see in 16x20 prints (a 2X print from 8x10 or a
> 4X print from 4x5) or even in 11x14 prints, (a 1.4X or 3X) though this
> is a much more subtle difference, I'd guess that you need somewhere
> around 30 lp/mm in the print to get the maximum quality that you can see
> with a naked eye.
I doubt if it is possible to get anywhere near 30 lp/mm on a print under
any circumstances (not even a contact print from a 35mm Tech Pan
negative). There are so many factors that degrade the image resolution
that I just don't think 30 lp/mm on the final print is acheiveable even
under the best case controlled conditions (let alone shooting low
contrast, complex three dimensional subjects under real world
conditions). I have not done much reading on actual printing paper
reolutions, but the one article I did read claimed a maximum resolution
13 lp/mm for Oriental Seagull Glossy.
> I know I want to put my eye right up next to a print
> (call this 10"-20"), reguardless of print size. Unless there is a
> barrier that prevents close observation of large prints, I find most
> people look at prints from about the same distance no matter what size
> the print is. If you keep your eye about the print diagonal or more
> from the print (which explains why billboards made from 35mm can look
> sharp when you drive by them many yards away), I don't see any problems
> with any size prints from 4x5, but I don't (and I don't see others)
> looking at prints that way.
I do not consider looking at a 30x40 print from a distance of 10"-20" to
be "viewing" the print. From that distance, you can't come close to
seeing the entire image at once. I consider this "examining" the
print. I'm not trying to argue semantics, nor am I being judgemental (I
do exactly the same thing). In fact, the sharper the print looks, the
closer I want to examine it to see just how much detail is there. When
I walk into a gallery I feel no desire to get any closer to an image
that looks like mush from across the room. If the image looks sharp
from a distance, it draws me in (assuming compelling subject matter).
I'm curious, do all photographers do this? Is this behavior unique to
photographers, or is it practiced by the population at large (aka:
normal people)?
Kerry Thalmann
John J. Stafford wrote:
>
> Kerry Thalmann <K.Tha...@worldnet.att.net> wrote:
> [snip]
>
> What he said. Read it again and again. Thanks, Kerry. Your work
> has saved me an enormous amount of retesting and questioning.
> We (I) owe you!
Hi John,
Thanks, I'm glad others are benefiting from our work. While I do
appreciate your kind words, the lion's share of the credit should go to
Chris Perez. He's the one slaving away in the darkroom souping all
these test negs and posting the results.
Kerry Thalmann
P.Groepper wrote:
> And for me (!) such rule of thumb is sufficient, because I don't want to
> enter into discussion about WHEN grain starts to become too visible,
> WHEN colour saturation is no longer satisfying etc.. It is a bit like
> with the performance of HiFi music equipment. And eventually I'd still
> prefer "good" music from a bad "radio" than vice versa. Quality in the
> frame we are discussing, is definitely not a binary yes/no thing.
Hi Peter,
Amen! All the testing in the world may produce interesting results (and
give us something to talk about in the newsgroups), but in the end, it's
what hangs on the wall that counts.
mla...@aol.com
In article <6mrs03$e...@bgtnsc01.worldnet.att.net>,
Kerry Thalmann <K.Tha...@worldnet.att.net> wrote:
>
> John Sparks wrote:
>
>
> > I know I want to put my eye right up next to a print
> > (call this 10"-20"), reguardless of print size. Unless there is a
> > barrier that prevents close observation of large prints, I find most
> > people look at prints from about the same distance no matter what size
> > the print is. If you keep your eye about the print diagonal or more
> > from the print (which explains why billboards made from 35mm can look
> > sharp when you drive by them many yards away), I don't see any problems
> > with any size prints from 4x5, but I don't (and I don't see others)
> > looking at prints that way.
>
> I do not consider looking at a 30x40 print from a distance of 10"-20" to
> be "viewing" the print. From that distance, you can't come close to
> seeing the entire image at once. I consider this "examining" the
> print. I'm not trying to argue semantics, nor am I being judgemental (I
> do exactly the same thing). In fact, the sharper the print looks, the
> closer I want to examine it to see just how much detail is there. When
> I walk into a gallery I feel no desire to get any closer to an image
> that looks like mush from across the room. If the image looks sharp
> from a distance, it draws me in (assuming compelling subject matter).
> I'm curious, do all photographers do this? Is this behavior unique to
> photographers, or is it practiced by the population at large (aka:
> normal people)?
>
> Kerry
If a print grabs my eye, I move up about as close as possible. And, this may
be interesting as well - if it's a really cool subject/print, I don't look at
the technical stuff very much. If it's not, then I get picky.
Mike
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Clyde Soles
Kerry Thalmann <K.Tha...@worldnet.att.net> wrote:
> If the image looks sharp
> from a distance, it draws me in (assuming compelling subject matter).
> I'm curious, do all photographers do this? Is this behavior unique to
> photographers, or is it practiced by the population at large (aka:
> normal people)?
Absolutely. The sharper it is, the closer I want to get to it to
luxuriate in the details. I doubt it's a universal sentiment though,
based on the number of posts by people who believe smaller formats are
"just as good."
Mathe Sandor S.C.
Kerry Thalmann (K.Tha...@worldnet.att.net) wrote:
: I do not consider looking at a 30x40 print from a distance of 10"-20" to
: be "viewing" the print. From that distance, you can't come close to
: seeing the entire image at once. I consider this "examining" the
: print. I'm not trying to argue semantics, nor am I being judgemental (I
: closer I want to examine it to see just how much detail is there. When
: I walk into a gallery I feel no desire to get any closer to an image
: from a distance, it draws me in (assuming compelling subject matter).
: I'm curious, do all photographers do this? Is this behavior unique to
: photographers, or is it practiced by the population at large (aka:
: normal people)?
I don't know about normal people, I don't know any (and haven't studied
them in a gallery, ... yet). I certainly do this, what you call examining
a print. Note that you can't see the entire scene in front of you anyway
so your eyes constantly scan. Moving close to a print so that it nearly
fills my entire visual field is part of the experience of viewing a good
print (I sit in the front 6 rows of movie theatres too).
In a print discussion group (Toronto Focal Forum) that I belong to, many
people bring binoculars to view the 16x20 prints from 10 - 20 feet so
that they don't have to get up, move around the chairs, etc to get close.
--
Sandor Mathe
san...@ca.ibm.com
Lee Carmichael
Thor:
I use a glass carrier all the time (Elwood user). I do have to clean the
glass some and probably more that most do but I have never had Newton rings with
even the cheapest glass available. I think the key is not to have it really
smashing the neg.
As usual,
Lee Carmichael
Thor Lancelot Simon wrote:
> In article <6moq4j$3...@bgtnsc01.worldnet.att.net>,
> Kerry Thalmann <K.Tha...@worldnet.att.net> wrote:
> >P.Groepper wrote:
> >
> >> One may argue about the mag.factor of 3.5, but I don't care to much
> >> about such details. Anything wrong with this approach?
> >
> >Hi Peter,
> >
> >I don't wish to argue, but I am curious as to what you think limits the
> >enlargement factor to 3.5. Is it on-film resolution or visible grain?
> >Based on the lens tests Chris Perez and I have been conducting, and
> >several articles I have read on the subject (and practical experience)
> >it would appear that on-film resolution would permit a much larger
> >enlargement factor.
>
> Yeah, *but*:
>
> Who uses glass negative carriers consistently? Bob Salomon and I argued
> viciously about this years ago and he was, frankly, right. Experimentation
> finally proved to me that negative flatness was far and away the limiting
> factor in the sharpness of my prints from large-format film. This is a
> much more severe problem for sheet film than for small roll film.
>
> I hate glass carriers. I just can't keep the things clean, I get newton
> rings, and all the other problems. I've compromised on a Negaflat; if I
> ever get an 8x10 enlarger I guess I'll grit my teeth and bear the hassle,
> though.
>
> Also, many people's enlargers are quite poorly aligned, often front-to-back
> which is generally a bit harder to adjust precisely than side-to-side,
> without a vacuum easel the paper's never totally flat (much less of an
> issue than film flatness however), and few darkrooms are constructed with
> proper care to isolating the enlarging bench from fan vibration.
>
> To top it all off, because of the various flatness and focus issues, 4x5
> is generally enlarged at significantly smaller apertures than 6x7 or 35mm,
> so the enlarging lens is generally diffraction-limited which again reduces
> the theoretical resolution of the end-to-end system, if it were otherwise
> perfect, which it is not.
>
> --
> Thor Lancelot Simon t...@rek.tjls.com
> "And where do all these highways go, now that we are free?"
Thor Lancelot Simon
Richard Knoppow
Saltzman had an accessory negative holder for their big 8x10
enlargers which clipped onto the film at the corners and stretched it
flat with springs. I've never seen one and don't have any idea about
how well they worked but its an indication that others also hated
glass holders :-)
Jean-David Beyer
Thor Lancelot Simon wrote (in part):
> Who uses glass negative carriers consistently? Bob Salomon and I argued
> viciously about this years ago and he was, frankly, right. Experimentation
> finally proved to me that negative flatness was far and away the limiting
> factor in the sharpness of my prints from large-format film. This is a
> much more severe problem for sheet film than for small roll film.
>
> I hate glass carriers. I just can't keep the things clean, I get newton
> rings, and all the other problems. I've compromised on a Negaflat; if I
> ever get an 8x10 enlarger I guess I'll grit my teeth and bear the hassle,
> though.
An option for 8x10 is to get a Zone VI 8x10 enlarger. They have a negative carrier
that is intended to keep the negatives flat without glass. Principle is much like
the Negaflat, but it may be that it does not scratch the negatives as much (if at
all) at the edges. (But try to examine one before you buy.)
--
Jean-David Beyer
Shrewsbury, New Jersey
Kerry Thalmann
Thor Lancelot Simon wrote:
> Who uses glass negative carriers consistently? Bob Salomon and I argued
> viciously about this years ago and he was, frankly, right. Experimentation
> finally proved to me that negative flatness was far and away the limiting
> factor in the sharpness of my prints from large-format film. This is a
> much more severe problem for sheet film than for small roll film.
>
> I hate glass carriers. I just can't keep the things clean, I get newton
> rings, and all the other problems. I've compromised on a Negaflat; if I
> ever get an 8x10 enlarger I guess I'll grit my teeth and bear the hassle,
> though.
Thor,
There are methods other than glass carriers to get reasonably good film
flatness. You've already mentioned the negaflat, and somebody else
mentioned the Zone VI carrier. I'm not doing much enlarging these days,
but one thing that used to work well for me was draftsman tape and the
regular glassless Omega clamshell carriers. I simply put a small strip
of tape over just the tip of each corner of the negative (outside the
printable image area). Tape down two corners, pull the neg tight and
tape down the other two. It doen't sound very elegant, but is cheap,
easy and works pretty well. Be sure to use draftsman tape, which
doesn't normally leave any adhesive residue. Only tape on the
non-emulsion side of the neg (that way if you do occasionally get a
little residue it is easy to clean off without damage to the emulsion).
I have used glass negative carriers on occasion. In addition to the
Newton rings, keeping all those surfaces dust free is a real pain. This
is especially true when making type R prints using a contrast mask.
Eight surfaces to try to keep dust free (four film and four glass).
BTW, given the emerging digital technologies, the problem of film
flatness during printing may become a non-issue (if you choose to go
this route). I have seen the results from the Evercolor Luminage
process and they are stunning. The film is held flat against the drum
during scanning, and the paper is also held (with a vacuum) to a larger
drum during printing (tri-color laser). Of course, this technology is
also available to the smaller formats, but it eliminates the film
flatness problem you site in large format enlarging. On the other end
of the timeline (and technology curve), there is always contact
printing. With a good frame, or a heavy cover glass, film flatness is
not a problem there either. See how far we've come in 150 years.
> Also, many people's enlargers are quite poorly aligned, often front-to-back
> which is generally a bit harder to adjust precisely than side-to-side,
> without a vacuum easel the paper's never totally flat (much less of an
> issue than film flatness however), and few darkrooms are constructed with
> proper care to isolating the enlarging bench from fan vibration.
Of course, these are all issues that can be (and should be) solved by
anyone serious about high quality printing. They are also issues not
specific to large format. In fact, the effects of mis-alignment,
vibration, etc. are greater for the smaller formats for a given print
size due to the higher magnification required (the vibrations, etc. are
also magnified more).
> To top it all off, because of the various flatness and focus issues, 4x5
> is generally enlarged at significantly smaller apertures than 6x7 or 35mm,
> so the enlarging lens is generally diffraction-limited which again reduces
> the theoretical resolution of the end-to-end system, if it were otherwise
> perfect, which it is not.
This is possibly true, but I don't think the diffraction limits of the
enlarging lens will have much impact on final print sharpness. I think
there are other factors that dominate (the resolving capabiltes of the
paper, for example) before the theoretcial diffraction limits of the
enlarging lens comes into play. Still, there are many factors, and they
are additive. Anyway, one more reason to favor the digital method. No
enlarging lens. Of course, there will be a different set of variables
limiting the results of the digital process, but from what I've seen so
far, this is a very promising technology, and it's going to only get
better (and less expensive).
Jeff/addesign
nospam...@mindspring.com (Scot W. Perry) wrote:
>I'll throw something new into your equations.
>It is my opinion that the actual enlarging process is the main culprit
>in quality loss. Mainly due to the projection of the image to produce
>larger sizes. As I deal mainly in the digital field I have found you
>can get phenomenal quality enlargements from even 35mm when you scan
>and digitaly print verses traditional photo enlargement. In fact we
>scanned a 35mm slide and made a 48 x 72 inch print yesterday that even
>a 6x7 traditionaly enlarged could not have matched. Of course a
>scanned larger format transparency would have unquestionably produced
>an even more impressive print.
I have to wonder about such a comparison, and the feasibility of
adequate storage. What was the scan resoluution, and output dfevice
resolution? How large was the image file? What criteria determines
adequate resolution?
I have only one experience with large digital images, and that was
from a 4x5 transparency. The print was 36x48 at about 75lpi, I believe
printed from an Encad Novajet. For adequate resolution, the image was
set up for 150 pixels/inch for the final size. Or it may have been
90lpi and 180 pixels. I don't have it on hand. As I recall, the LZW
compressed TIF file ran about 65MB.
As the cost of CD burners comes down, I suppose digital image storage
becomes more practical (write-only CDs at about a buck, verses
$couple-hundred for a 100mb JAZ disk). But film still has a practical
advantage in cost-efffective storage of maximum image data. Consider
grains-per-inch vs. the highest resolution you can scan, and still
manage the file.
My personal interest is lithography at 16x20 or 20x24, 175 to 200 line
screen, requiring 350 to 400 pixels/inch. That's also up in the 65-75
MB range for image files. High-end drum scanning for advertising or
publishing used to mean three passes per screen-line-- I don't know if
anyone bothers with that for large scale work.
>Scot Perry
>Artworx
>digital imaging services and supplies
Would that suggest a possible bias toward digital technology?
Jeff/addesign
++++++++++++++++++++++++++++++++++++++++++++++++++++++++
If God had intended man to shoot revolvers single action,
Smith & Wesson would build them that way.
++++++++++++++++++++++++++++++++++++++++++++++++++++++++
Scot W. Perry
The old Novajets were 300 dpi machines an average scan would be 100
dpi at the final output size anything over 125 would have been a
wasterd effort you'd never see it. The new Novajets are 600 dpi so
that equation changes and are also significantly better looking gone
is alot of the coarse sandy appeareance seen on many inkjet prints but
if you want to see some amazing prints check out lambda and pegasus
prints they are a photographic process and the sharpness on the
pegasus is almost scary.
Jeff/addesign
nospam...@mindspring.com (Scot W. Perry) wrote:
>The old Novajets were 300 dpi machines an average scan would be 100
>dpi at the final output size anything over 125 would have been a
>wasterd effort you'd never see it. The new Novajets are 600 dpi so
>that equation changes and are also significantly better looking gone
>is alot of the coarse sandy appeareance seen on many inkjet prints but
>if you want to see some amazing prints check out lambda and pegasus
>prints they are a photographic process and the sharpness on the
>pegasus is almost scary.
90lpi, 100lpi, 125lpi, or whatever, they make adequate posters, but
can't compare in quality to 200line 4-color lithography, which
requires a much higher resolution scan, and commensurate increase in
storage requirements. Lambda & Pegasus prints come from what device,
at what cost, and what reslution? How would they comarpare to a
straight photographic print of the same dimension, on Kodak Duratrans?
On a related note, the service bureau up the street bought a Kodak
digital color proofing printer, for $14,000 about 4 months ago. It
stopped working. Kodak providesa 60 day warranty. The cost of repair
is $8000. The service bureau electerd to scrap the machine rather than
pay Kodak to fix it.
Jeff/addesign a.a #1063
****************************************************************
Tantum religio potuit suadere malorum--Lucretius, 1st c. BC
"So vast is the sum of the iniquities that religion has induced."
****************************************************************
Barry Sherman
Lee Carmichael <cl...@flash.net> wrote:
> I use a glass carrier all the time (Elwood user). I do have to clean the
>glass some and probably more that most do but I have never had Newton rings with
>even the cheapest glass available. I think the key is not to have it really
>smashing the neg.
Unlike Lee I've had extensive problems with Newton's rings. And,
also like Lee, I've found that the best solution seems to be
preventing the cover glass from pressing too strongly on the
film.
In a previous enlarger configuration I had the situation where
the head rested its weight directly on the negative carrier. I
had the worst Ring problems with this setup. In its current
configuration the head does not rest directly on the carrier
and the cover glass is separate piece of glass which rests
on the film. (This is a Condit pin registration carrier.)
I still have trouble with Rings but nowhere near as badly
as before.
Often the problem is cured by putting spacers around the edges of
the film to keep the glass from pressing tightly onto the
film. The spacers are strips of sheet film cut from film
which is slightly thicker than the film being printed. Helps
a lot.
Barry
--
Barry Sherman | Art does not reproduce what we see.
Suma Technologies, LLC | It makes us see. -- Paul Klee
My opinions, not Suma's |