Webcam vs DSLR Target Field of View
Hughes
Supposed both of them has pixel pitch of 5 micron. The
webcam has resolution of 640x480. The DSLR has resolution
of 10 Megapixel. When taking pictures of target, would both
cover the same image field of view? But then, can't you
consider the webcam sensor as located in the center portion
(smaller region) of the DSLR sensor chip, hence the webcam
is supposed to image only the central portion of the image
with all the sides black out? Or is it because the lens of
the webcam is able to take all field of view and converge
it to the center?
Or another way to look at it. Supposed you use a 640x480
webcam and put it in the image plane of the Canon 300 F/2.8
EF. Would the image you see the tiny portion of the center
of the target only or would you see the whole image???
Hu
Me
That's a really dumb question with an obvious answer. Either you've
been reading far too much for your mind to digest (but are capable of
regurgitating parts of it in a semi-coherent manner), or you're a troll.
I'll give you the benefit of the doubt and suspect that it's just the
latter, because I really wouldn't want to call you an idiot, as I'm
usually too polite.
Hughes
>
> - Show quoted text -
No troll dude. I'm installing this old webcam and it can't
run.. thinking of buying a new one.. but I remember before when used
it years ago the resolution seemd to be quite low. But when they used
webcam in astrophotography, it can image the planets. So maybe it has
to do with the lens? Just want to be sure because I'm going out to buy
a webcam in the store and if there are choices, I'd like to select one
compatible with astrophotography. Well. Rather than getting a Canon
1000D. I may just get a webcam to image my target which is bees and
flowers and want to
see it to the resolving limit allowed.. I'm not interested in
the sides or don't need larger field of view.. so I'm thinking if
640x480 webcam is sufficient for me as it has both the
same 5 micron pixel as the Canon 1000D.
Hughes
Hughes
>
> - Show quoted text -
To add to the above.. i was kinda thikning that the 5 micron
may be the sensel and the separation between pixels
could be greater than it resulting in poor resolution when
getting the same field of view than the DSLR CCD. But
then it could be the lens itself solely and whenever a
sensel is 5 micron, all CCDs from webcam and dslr would
have the same support chip dimension around it.
Now if it's all 100% got to do with the lens. This means a
webcam is sufficient for my application in my 1000mm
russian telephoto f/10 with 1.25" visual back adapter.. Now the next
obvious question is.. what webcam has the closest
quality as a Canon 1000D?? I think it's reasonable because
the webcam can be 640x480 only but it's sensor could be
using some modern implementation that could not be far
from the Canon 1000D. Is there such??
Hughes
Jürgen Exner
>Supposed both of them has pixel pitch of 5 micron. The
>webcam has resolution of 640x480. The DSLR has resolution
>of 10 Megapixel. When taking pictures of target, would both
>cover the same image field of view?
Guess what, even with just the DSLR with 10MP you are getting a
different field of view depending upon what lens or what focal length on
a zoom lens you are using.
Now, which of those infinite number of fields of view would you like to
compare to the web cam?
jue
Hughes
Here's what I want.
I have a russian Rubinar 4" Telephoto F/10 with M42
screw. But because there is an M42-Canon EOS
adaptor. I can use any Canon EOS. I initially planned to get
a Canon 1000D. But just found out that one could
get a webcam and it can produce the same detail
(that is, the central portion of the canon target
image). So I was wondering what the rule of thumb
in this scenerio. So with my Telephoto above,
what field of view can it produce in a Canon 1000D?
Would a Canon 300D produce other field of view?
What webcam can I use such that it can produce
the same image scale like the Canon but only
taking the central portion of the image (I'm not
interested in the whole image because I'm using
doing this to understand certain optical physics).
Hughus
Jürgen Exner
>On Apr 24, 1:28 pm, Jürgen Exner <jurge...@hotmail.com> wrote:
>> Hughes <eugenhug...@gmail.com> wrote:
>> >Supposed both of them has pixel pitch of 5 micron. The
>> >webcam has resolution of 640x480. The DSLR has resolution
>> >of 10 Megapixel. When taking pictures of target, would both
>> >cover the same image field of view?
>>
>> Guess what, even with just the DSLR with 10MP you are getting a
>> different field of view depending upon what lens or what focal length on
>> a zoom lens you are using.
>> Now, which of those infinite number of fields of view would you like to
>> compare to the web cam?
>
>screw. But because there is an M42-Canon EOS
>adaptor. I can use any Canon EOS. I initially planned to get
>a Canon 1000D. But just found out that one could
What is the focal length of that lens?
>get a webcam
What is the focal length and the sensor size on that webcam?
>and it can produce the same detail
>(that is, the central portion of the canon target
>image). So I was wondering what the rule of thumb
>in this scenerio. So with my Telephoto above,
>what field of view can it produce in a Canon 1000D?
What is the focal length of that lens? A 18mm lens obviusly has a very
different field of view than a 1000mm lens.
>Would a Canon 300D produce other field of view?
The sensor size on both cameras is virtually identical, therefore the
same lens will have the identical field of view on both cameras.
>What webcam can I use such that it can produce
>the same image scale like the Canon but only
>taking the central portion of the image
I have no idea what you mean by this.
jue
Bob Larter
> To add to the above.. i was kinda thikning that the 5 micron
> may be the sensel and the separation between pixels
> could be greater than it resulting in poor resolution when
> getting the same field of view than the DSLR CCD. But
> then it could be the lens itself solely and whenever a
> sensel is 5 micron, all CCDs from webcam and dslr would
> have the same support chip dimension around it.
No.
> Now if it's all 100% got to do with the lens. This means a
> webcam is sufficient for my application in my 1000mm
> russian telephoto f/10 with 1.25" visual back adapter.. Now the next
> obvious question is.. what webcam has the closest
> quality as a Canon 1000D?? I think it's reasonable because
> the webcam can be 640x480 only but it's sensor could be
> using some modern implementation that could not be far
> from the Canon 1000D. Is there such??
You're not going to be able to find a webcam with quality anything like
that of a DSLR.
--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
Hughes
> Hughes <eugenhug...@gmail.com> wrote:
> >On Apr 24, 1:28 pm, Jürgen Exner <jurge...@hotmail.com> wrote:
> >> Hughes <eugenhug...@gmail.com> wrote:
> >> >Supposed both of them has pixel pitch of 5 micron. The
> >> >webcam has resolution of 640x480. The DSLR has resolution
> >> >of 10 Megapixel. When taking pictures of target, would both
> >> >cover the same image field of view?
>
> >> Guess what, even with just the DSLR with 10MP you are getting a
> >> different field of view depending upon what lens or what focal length on
> >> a zoom lens you are using.
> >> Now, which of those infinite number of fields of view would you like to
> >> compare to the web cam?
>
> >I have a russian Rubinar 4" Telephoto F/10 with M42
> >screw. But because there is an M42-Canon EOS
> >adaptor. I can use any Canon EOS. I initially planned to get
> >a Canon 1000D. But just found out that one could
>
> What is the focal length of that lens?
>
1,000mm.
> >get a webcam
>
> What is the focal length and the sensor size on that >webcam?
I still haven't bought a webcam that's why I wrote
this thread. I'm thinking whether if I buy a webcam
with 5.7 micron pixel size the same size as the
Canon 1000D pixel, I'd be able to get the central
image of the target with same pixel scale (see
last paragraph of this thread to explain).
>
> >and it can produce the same detail
> >(that is, the central portion of the canon target
> >image). So I was wondering what the rule of thumb
> >in this scenerio. So with my Telephoto above,
> >what field of view can it produce in a Canon 1000D?
>
> What is the focal length of that lens? A 18mm lens obviusly has a very
> different field of view than a 1000mm lens.
>
> >Would a Canon 300D produce other field of view?
>
> The sensor size on both cameras is virtually identical, therefore the
> same lens will have the identical field of view on both cameras.
>
> >What webcam can I use such that it can produce
> >the same image scale like the Canon but only
> >taking the central portion of the image
>
> I have no idea what you mean by this.
Well.. Using the 1000mm telephoto, Imagine the
Canon 1000D taking a shot of your entire house
at a distance and whole house taken. Using a webcam at the same
distance and same 1000mm telephoto, the image taken would be only the
tiny central portion of your
house or only say the door. But with same detail or
pixel scale. Agree?
Hu
>
> jue- Hide quoted text -
Hughes
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -
I finally got my old webcam to work, but upon removing
the lens, I can't make it get any images in the
1000mm 4" telephoto. I put it in the 44.5mm flange
distance where the CCD of the Canon 300D/1000D is
supposed to be located. Anyone know why?
The webcam is 640x480 1/4 progressive scan.
Compare it to the Canon 1000D with 3888 x 2592
resolution.
I'm assuming that if the Canon can take picture
of a house (all contained in the picture) with the 1000mm Telephoto,
the webcam with smaller chip can only
take picture of the door.. both having the same pixel
scale (or the pixel containing same detail since
it is lets say both 5 micron).
But before delving into that. How come I can't even let the webcam see
any images in the telephoto? It's just white image, not even any
structure of the house can be seen nor
colors. Any genius know why??
Hughes
Hughes
1/4" color progressive CMOS
640×480pixels
Lens Specification
F=2.4,f=4.9mm,View Angle 54
See:
http://www.a4tech.com/ennew/product.asp?cid=77&scid=89&id=253
> Compare it to the Canon 1000D with 3888 x 2592
> resolution.
> I'm assuming that if the Canon can take picture
> of a house (all contained in the picture) with the 1000mm Telephoto,
> the webcam with smaller chip can only
> take picture of the door.. both having the same pixel
> scale (or the pixel containing same detail since
> it is lets say both 5 micron).
>
> But before delving into that. How come I can't even let the webcam see
> any images in the telephoto? It's just white image, not even any
> structure of the house can be seen nor
> colors. Any genius know why??
>
> Hughes- Hide quoted text -
David J Taylor
[]
> Details:
> 1/4" color progressive CMOS
> 640×480pixels
>
> Lens Specification
> F=2.4,f=4.9mm,View Angle 54
>
> See:
> http://www.a4tech.com/ennew/product.asp?cid=77&scid=89&id=253
So the lens has an entrance pupil of 2mm when wide open. Are you matching
your telescope to that?
David
Hughes
My 1000mm f/10 telephoto has aperture of 4 inches, so
entrance pupil is 4 inches.
I finally got to focus with my Webcam. I wasn't able
to focus earlier because it was out of focus :)
Now after checking. It is correct that the webcam
can only image a very tiny portion of the target
when using the 1000mm telephoto. Therefore
it is really true that the lens of the webcam is
able to take in the whole scene into the sensor,
while that of telephoto can spread it to larger
sensor.
Now what's left to do is to look for the best webcam
in the world. But first something I noticed. Digicam
has pixel pitch the size of 2 micron while Webcam
has pixel pitch the size of 5 micron. Why is the pixel
pitch of Webcam larger? It's large enough to match
the pixel pitch of DSLR, is this one reason why
astrophotography uses webcam a lot besides the
ease of downloading images.
Now having mentioned that the pixel pitch of webcam
and DSRL is similar in roughly 5 micron. What is
the best webcam in the world in terms of noise
suppression and color saturation that it can be
at least 3/4 to that of DSLR in quality (or 1/2 if
3/4 is not possible??) Anyone?
Hu
David J Taylor
[]
> Now having mentioned that the pixel pitch of webcam
> and DSRL is similar in roughly 5 micron. What is
> the best webcam in the world in terms of noise
> suppression and color saturation that it can be
> at least 3/4 to that of DSLR in quality (or 1/2 if
> 3/4 is not possible??) Anyone?
>
> Hu
I think you will find that many Webcams are designed simply for
surveillance purposes, and that cost, not quality, is the driving factor.
David
ASAAR
> That's a really dumb question with an obvious answer. Either you've
> been reading far too much for your mind to digest (but are capable of
> regurgitating parts of it in a semi-coherent manner), or you're a troll.
> I'll give you the benefit of the doubt and suspect that it's just the
> latter, because I really wouldn't want to call you an idiot, as I'm
> usually too polite.
Because he simultaneously demonstrates knowledge, extreme
ignorance and a screwy lack of logic, Hughes can only be out for a
lark, a troll's walk in the park. I mean, instead of talking
pixels, he refers to sensels, yet hasn't a clue about cheap webcam
sensors. It wouldn't surprise me if this wasn't our pathetic
anti-DSLR sock puppet troll, tired of his old persona and trying a
new one on for size.
whisky-dave
"Hughes" <eugen...@gmail.com> wrote in message
news:69e0d238-c260-46b7...@l16g2000pra.googlegroups.com...
On Apr 24, 4:50 pm, "David J Taylor" <david-tay...@blueyonder.not-this-
part.nor-this.co.uk.invalid> wrote:
> Hughes wrote:
>
> []
>
> > Details:
> > 1/4" color progressive CMOS
> > 640×480pixels
>
> > Lens Specification
> > F=2.4,f=4.9mm,View Angle 54
>
> > See:
> >http://www.a4tech.com/ennew/product.asp?cid=77&scid=89&id=253
>
> So the lens has an entrance pupil of 2mm when wide open. Are you matching
> your telescope to that?
>
> David
}My 1000mm f/10 telephoto has aperture of 4 inches, so
}entrance pupil is 4 inches.
}I finally got to focus with my Webcam. I wasn't able
}to focus earlier because it was out of focus :)
What makes you think a webcam is suitable for this remember that the webcam
has both the sensor and the lens in a single unit they are fixed, they go
together.
}Now after checking. It is correct that the webcam
}can only image a very tiny portion of the target
}when using the 1000mm telephoto. Therefore
}it is really true that the lens of the webcam is
}able to take in the whole scene into the sensor,
}while that of telephoto can spread it to larger
}sensor.
Don;t think so.
What relevance is it that the telephoto spreads over a wider sensor. ?
A cameras lens is designed so that the image produced covers the sensor
of any camera that the lens has been designed for, while the webcam
lens is only designed to cover the sensor in ONE camera the webcam and
nothing else.
}Now what's left to do is to look for the best webcam
}in the world.
I could look for the most expensive motorbike in the wolrd and expect it
to perform the same as a push bike because both have 2 wheels.
Not really a webcam is mostly used for moving images.
You could use a camcorder in the same way.
Why don;t people forget about DLSRs and just get a camcorder......
The optical quality is one reason.
If you want a large optical magnification then why not buy a camcorder
rathern than a DLSR or a webcam.
}But first something I noticed. Digicam
}has pixel pitch the size of 2 micron while Webcam
}has pixel pitch the size of 5 micron. Why is the pixel
}pitch of Webcam larger?
Could it be the webcam has lower resolution.
Most webcams are for 72DPI viewing,
I don;t think any photographic lenses would sell with that spec,
they are expected to resolve at DPI is the 1000s
} It's large enough to match
}the pixel pitch of DSLR, is this one reason why
}astrophotography uses webcam a lot besides the
}ease of downloading images.
where have you got that idea from ?
Webcams might be use as spotting scopes.
I doubt the Hubble space telescope is using a webcam.
Most Astrophotography uses specialist equipment of relatively large focal
lengths
unless they are mapping the sky.
webcams generally have wider fields of view in comparison.
}Now having mentioned that the pixel pitch of webcam
}and DSRL is similar in roughly 5 micron. What is
}the best webcam in the world in terms of noise
}suppression and color saturation that it can be
}at least 3/4 to that of DSLR in quality (or 1/2 if
}3/4 is not possible??) Anyone?
The thing about proper astrophotography regarding noise is the temperature
of the sensor,
they like to keep it to as close to absolute zero as possible which usually
requires
liquid nitrogen or better still liquid helium at around -270C.
Hughes
My experience is mostly analog telescopy or
traditional amateur astronomy where one looks
at saturn, cassini, galaxies, nebulae, planets,
etc. I haven't tried astrophotography as the
actual visual experience is better. Then I learnt
that using digicams, one can image the airy
disc diameter itself or even image the resolving
limit of the scope. This is great because one
can know from the images itself how big
exactly is the range of the airy disc, etc. Now
viewing extended objects, I wonder how it
performs. Then to understand it better, I
want to try terrestrial photography to see
effects of extended object and resolution.
Slowly I go into the world of digital photography
and learning about it each day. No, not a troll.
After gaining crucial knowledge, I'd just leave
the group anytime soon.
Hu
Hughes
> "Hughes" <eugenhug...@gmail.com> wrote in message
What you haven't consider (and which I just realised
today) is that when you take off the lens of a webcam,
and put the ccd in a big telephoto or even Hubble, the
resolution of it is equal to expensive dedicated CCDs or even DSLR
because the determining factor in getting
the pixel scale in arcsecond is the pixel size. So
if the webcam say has 4 micron and the Hubble
CCD has 4 micron, they would have similar resolution.
Surprise? Well, I was surprised to just learnt it today.
Hu
> Most Astrophotography uses specialist equipment of relatively large focal
> lengths
> unless they are mapping the sky.
> webcams generally have wider fields of view in comparison.
>
> }Now having mentioned that the pixel pitch of webcam
> }and DSRL is similar in roughly 5 micron. What is
> }the best webcam in the world in terms of noise
> }suppression and color saturation that it can be
> }at least 3/4 to that of DSLR in quality (or 1/2 if
> }3/4 is not possible??) Anyone?
>
> The thing about proper astrophotography regarding noise is the temperature
> of the sensor,
> they like to keep it to as close to absolute zero as possible which usually
> requires
> liquid nitrogen or better still liquid helium at around -270C.- Hide quoted text -
whisky-dave
On Apr 24, 7:08 pm, "whisky-dave" <whisky-d...@final.front.ear> wrote:
> "Hughes" <eugenhug...@gmail.com> wrote in message
> I doubt the Hubble space telescope is using a webcam.
What you haven't consider (and which I just realised
today) is that when you take off the lens of a webcam,
and put the ccd in a big telephoto or even Hubble, the
resolution of it is equal to expensive dedicated CCDs or even DSLR
where do you get that idea ?
because the determining factor in getting
the pixel scale in arcsecond is the pixel size. So
if the webcam say has 4 micron and the Hubble
CCD has 4 micron, they would have similar resolution.
Surprise? Well, I was surprised to just learnt it today.
Does that actually mean anything though ?
Savageduck
I have to agree.
This OP and the evidence of the "Matching Pixel Size and Telescope"
debate together with his posts as "Eugene" seem to have established
"Hughes" troll credentials.
He is in total "mind fuck" mode.
He may not be a troll, just blind to the ridiculousness of all of his
posts. He may be sincere in hia alleged intellectual pursuit, but there
is an esoteric quality to all of his posts which are beyond wacky.
To "Hughes"
If you are still into the "astrophotography" stuff try:
http://www.telescope.com/control/category/~category_id=astro-imaging_camera/~pcategory=astro-imaging
Regards,
Savageduck
Leonard Oglesby
Now you are sounding like Measekite.
You are doing a solid job of establishing your troll credentials "Eugene"
Regards,
Savageduck
Hughes
>
> Regards,
> Savageduck- Hide quoted text -
>
> - Show quoted text -
Naw. I just want to know how big is airy disc in each picture,
especially terrestrially.
Now with many data shared by you guys, I now have narrowed
it to the following possibilities.
For my Rubinar 4" Telephoto F/10 with 1.16 arcsecond dawes' limit
and 1000mm focal length.
1.16 arcsecond/2 = 206265 x pixel pitch/1000mm
optimal pixel pitch = 2.8 micron
So I need to get either a webcam or dslr near 2.8 micron.
Nearest available dlsr is Canon 500D with 4.7 micron.
Nearest webcam is still unknown and search in progress.
Now if quality of webcam pixel is below 60% of dslr,
then I may just get the dslr.
If latter chosen, Have to decide between Canon 500D and
Canon 1000D. Former is 12 MP, 4.7 micron, Latter is 10 MP,
5.7 micron.
If webcam is really out of the question because of poor
quality (I don't mind the small field of view because I just
want to image airy discs and know how it is located in
images). Then need to decide further with following
conditions.
If I use photography more than twice a week, I'd get the
Canon 500. If I use it once a week, I'd get the Canon 1000D.
If I use it once a month, I may just look for someone with
Canon 400D and view the airy disc with my telephoto.
I won't buy a low priced Canon 300D anymore because of its
lack of mirror lockup which you guys state is necessary for
f/10 imaging.
Analysis mode ongoing. Scrutinizing optics and narrowing
down options engaged.
Eugene Hughes
eugen...@gmail.com
Me
pitch of 2.8 microns worthwhile (ie about equivalent to 40 megapixels
give or take a few million at APS-C size), then I'll consume a pound of
butter washed down with a pint of warm beer, video the result and post
it on you tube, and post the link for your viewing pleasure.
At f10 airy disk diameter is about 4x that pixel pitch, and the system
is (severely) diffraction limited.
Somewhere back in one of your threads you came to your own conclusion
that pixel pitch of an old Canon 300d might be okay. You should have
stuck with that. IIRC though, the 300d doesn't have MLU (without
firmware hack).
Ron
Use the self-timer to get around the lack of MLU.
Bob Larter
He says he's removed the lens. I have no idea how he's attached the
reflector to his webcam, & I'm a little scared to ask. ;^)
Bob Larter
[...]
> Now what's left to do is to look for the best webcam
> in the world. But first something I noticed. Digicam
> has pixel pitch the size of 2 micron while Webcam
> has pixel pitch the size of 5 micron. Why is the pixel
> pitch of Webcam larger?
Because it's much lower resolution than a digicam.
David J Taylor
> David J Taylor wrote:
[]
>> So the lens has an entrance pupil of 2mm when wide open. Are you
>> matching your telescope to that?
>
> He says he's removed the lens. I have no idea how he's attached the
> reflector to his webcam, & I'm a little scared to ask. ;^)
I wasn't aware of that when I wrote my reply. If he already has the
Webcam, though, why is he now asking which is the best? I'm afraid I gave
up after his reply to me.
Cheers,
David
Hughes
Initially, I was able connect the webcam without lens to
a 1" eyepiece extension tube. It is perfect for it. What I
found out is that the field of view is so small. So since
there is no 2 megapixel webcam that has twice the 1/4" sensor
and the best webcam in the world.. the Philips Toucam Pro
and Celestron NexImager webcam has only 640x480, 1/4" sensor (http://
www.amazon.com/gp/product/B0002X5Q72/ref=s9_sims_gw_s2_p114_t1?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-1&pf_rd_r=0Z0GTZR9RPAGK8XEE5JF&pf_rd_t=101&pf_rd_p=470938131&pf_rd_i=507846)
I may just settle for a Canon 1000D. But then I heard rumor
prices of it would go down with the introduction of 500D. I
wonder how low the prices of the 1000D would be.. in a few
weeks. I wonder where I can reliably inquire about whether
prices would get down.. how long from now. and how much.
I would only get the 1000D to experience optical physics
and theoretical principles, then sell it later.
Hughes
Hughes
> On Apr 25, 3:44 pm, "David J Taylor" <david-tay...@blueyonder.not-this-
>
>
>
>
>
> part.nor-this.co.uk.invalid> wrote:
> > Bob Larter wrote:
> > > David J Taylor wrote:
> > []
> > >> So the lens has an entrance pupil of 2mm when wide open. Are you
> > >> matching your telescope to that?
>
> > > He says he's removed the lens. I have no idea how he's attached the
> > > reflector to his webcam, & I'm a little scared to ask. ;^)
>
> > I wasn't aware of that when I wrote my reply. If he already has the
> > Webcam, though, why is he now asking which is the best? I'm afraid I gave
> > up after his reply to me.
>
> > Cheers,
> > David
>
> Initially, I was able connect the webcam without lens to
> a 1" eyepiece extension tube. It is perfect for it. What I
> found out is that the field of view is so small. So since
> there is no 2 megapixel webcam that has twice the 1/4" sensor
> and the best webcam in the world.. the Philips Toucam Pro
> I may just settle for a Canon 1000D. But then I heard rumor
> prices of it would go down with the introduction of 500D. I
> wonder how low the prices of the 1000D would be.. in a few
> weeks. I wonder where I can reliably inquire about whether
> prices would get down.. how long from now. and how much.
> I would only get the 1000D to experience optical physics
> and theoretical principles, then sell it later.
>
>
> - Show quoted text -
But my primary reason I plan to get 1000D instead of
retaining webcam is because there is highly statistical
probability that a Canon CCD has better electronic
support components than webcam, less noise,
better Bayer filter, more contrast, etc. I think that
perhaps a webcam CCD has 1/3 the quality of
a Canon EOS? If webcam has 2/3 quality of
Canon, I can live with it. But it seems the quality
is lesser than 2/3. I wonder where I can see side
by side comparison of webcam CCD and Canon
EOS CCD like whether the Bayer color filters in
the former is half as bad as the Canon or 1/3
as bad.
Hughes
N
>But my primary reason I plan to get 1000D instead of
>retaining webcam is because there is highly statistical
>probability that a Canon CCD has better electronic
>support components than webcam, less noise,
>better Bayer filter, more contrast, etc. I think that
>perhaps a webcam CCD has 1/3 the quality of
>a Canon EOS? If webcam has 2/3 quality of
>Canon, I can live with it. But it seems the quality
>is lesser than 2/3. I wonder where I can see side
>by side comparison of webcam CCD and Canon
>EOS CCD like whether the Bayer color filters in
>the former is half as bad as the Canon or 1/3
>as bad.
>
>Hughes
But Canon don't make DSLR with CCDs.
--
N
Hughes
> "Hughes" <eugenhug...@gmail.com> wrote in message
Or Canon DSLR with Cmos. All my inquiries may seem
strange but it is perfectly normal for astrophotographers.
I just couldn't find an astrophotography newsgroup where
I could ask the following for instance:
"Hi Guys, how good are webcams (in percentage) such as the
Celestron NexImager or Philip Toucam compared to
Canon DSLR 1000D when they both have 5 micron
and have same pixel scale for planetary imaging..."
But I couldn't find a astrophotography newsgroup so end
up here where pixel scale and cassini divisions are strange
stuff for mostly portrait and Britney or party photographers.
I'm basically a visual planetary observer but planned to
try CCD imaging. Also I want to famiiarize myself with
how big are airy discs in extended objects (by
first trying out resolution charts in terrestrial) so I can
gauge lens quality better in the future when I resold
my gear and got new ones.
So if someone can show me a cool astrophotography
newsgroup or forum I haven't encountered before. Let
me know so I'm outta here asap :) I seek for them but
haven't encountered one with hundreds of multi brand
digicam users that can seemingly only be found here.
Hu
Me
If you're used to capturing photons which might have taken thousands or
millions or even billions of years to arrive here, then being pedantic
about a decade or so of progress on planet Earth is just plain silly.
Paul Furman
> Supposed both of them has pixel pitch of 5 micron. The
> webcam has resolution of 640x480. The DSLR has resolution
> of 10 Megapixel. When taking pictures of target, would both
> consider the webcam sensor as located in the center portion
> (smaller region) of the DSLR sensor chip, hence the webcam
> is supposed to image only the central portion of the image
> with all the sides black out? Or is it because the lens of
> the webcam is able to take all field of view and converge
> it to the center?
>
> Or another way to look at it. Supposed you use a 640x480
> webcam and put it in the image plane of the Canon 300 F/2.8
> EF. Would the image you see the tiny portion of the center
> of the target only or would you see the whole image???
Right, the webcam catches the center.
Here's that exact experiment:
http://edgehill.net/Misc/photography/9-22-07-webcam
The DSLR is a little better in spite of being enlarged to match... I
forget all the details, read the notes & subgalleries, hover over the
images & thumbnails for more.
Here's the same exercise for extreme macro closeup work:
http://edgehill.net/Misc/photography/1-3-09-webcam-macro
--
Paul Furman
www.edgehill.net
www.baynatives.com
all google groups messages filtered due to spam
Bob Larter
> Bob Larter wrote:
>> David J Taylor wrote:
> []
>>> So the lens has an entrance pupil of 2mm when wide open. Are you
>>> matching your telescope to that?
>>
>> He says he's removed the lens. I have no idea how he's attached the
>> reflector to his webcam, & I'm a little scared to ask. ;^)
>
> I wasn't aware of that when I wrote my reply. If he already has the
> Webcam, though, why is he now asking which is the best?
Damned if I know.
> I'm afraid I
> gave up after his reply to me.
Yeah, I couldn't figure out half his questions.
Bob Larter
Why don't you just buy a used 10D or some other older model?
Bob Larter
Canon uses CMOS sensors, not CCDs.
> support components than webcam, less noise,
> better Bayer filter, more contrast, etc. I think that
> perhaps a webcam CCD has 1/3 the quality of
> a Canon EOS?
Not even close. Probably more like 1/100th.
> If webcam has 2/3 quality of
> Canon, I can live with it. But it seems the quality
> is lesser than 2/3. I wonder where I can see side
> by side comparison of webcam CCD and Canon
> EOS CCD like whether the Bayer color filters in
> the former is half as bad as the Canon or 1/3
> as bad.
Good luck with that - I don't like your chances.
ASAAR
>> I wasn't aware of that when I wrote my reply. If he already has the
>> Webcam, though, why is he now asking which is the best?
>
> Damned if I know.
It's to replace a portion of Hugh's damaged ocular implant, so
only the best is good enough. Be wary and keep your distance or he
may initiate the hive's assimilation process and as everyone knows,
resistance is futile.
Bob Larter
I'd quote Vogon poetry at you, but mercifully, I seem to have forgotten
it all.
Tzortzakakis Dimitrios
? "Bob Larter" <bobby...@gmail.com> ?????? ??? ??????
news:49f34284$1...@dnews.tpgi.com.au...
> ASAAR wrote:
>> On Sun, 26 Apr 2009 00:10:04 +1000, Bob Larter wrote:
>>
>>>> I wasn't aware of that when I wrote my reply. If he already has the
>>>> Webcam, though, why is he now asking which is the best?
>>> Damned if I know.
>>
>> It's to replace a portion of Hugh's damaged ocular implant, so
>> only the best is good enough. Be wary and keep your distance or he
>> may initiate the hive's assimilation process and as everyone knows,
>> resistance is futile.
>
> I'd quote Vogon poetry at you, but mercifully, I seem to have forgotten it
> all.
As plurdled gabbleblotchits on a lurgid bee.
--
Tzortzakakis Dimitrios
major in electrical engineering
mechanized infantry reservist
hordad AT otenet DOT gr
Hughes
> Hughes wrote:
> > On Apr 25, 5:13 pm, Hughes <eugenhug...@gmail.com> wrote:
> >> On Apr 25, 3:44 pm, "David J Taylor" <david-tay...@blueyonder.not-this-
>
> >> part.nor-this.co.uk.invalid> wrote:
> >>> Bob Larter wrote:
> >>>> David J Taylor wrote:
> >>> []
> >>>>> So the lens has an entrance pupil of 2mm when wide open. Are you
> >>>>> matching your telescope to that?
> >>>> He says he's removed the lens. I have no idea how he's attached the
> >>>> reflector to his webcam, & I'm a little scared to ask. ;^)
> >>> I wasn't aware of that when I wrote my reply. If he already has the
> >>> Webcam, though, why is he now asking which is the best? I'm afraid I gave
> >>> up after his reply to me.
> >>> Cheers,
> >>> David
> >> Initially, I was able connect the webcam without lens to
> >> a 1" eyepiece extension tube. It is perfect for it. What I
> >> found out is that the field of view is so small. So since
> >> there is no 2 megapixel webcam that has twice the 1/4" sensor
> >> and the best webcam in the world.. the Philips Toucam Pro
> >> I may just settle for a Canon 1000D. But then I heard rumor
> >> prices of it would go down with the introduction of 500D. I
> >> wonder how low the prices of the 1000D would be.. in a few
> >> weeks. I wonder where I can reliably inquire about whether
> >> prices would get down.. how long from now. and how much.
> >> I would only get the 1000D to experience optical physics
> >> and theoretical principles, then sell it later.
>
> >> Hughes- Hide quoted text -
>
> >> - Show quoted text -
>
> > But my primary reason I plan to get 1000D instead of
> > retaining webcam is because there is highly statistical
> > probability that a Canon CCD has better electronic
>
> Canon uses CMOS sensors, not CCDs.
>
> > support components than webcam, less noise,
> > better Bayer filter, more contrast, etc. I think that
> > perhaps a webcam CCD has 1/3 the quality of
> > a Canon EOS?
>
> Not even close. Probably more like 1/100th.
>
That's because you also consider the lens of the
webcam and the dslr which is the limiting factor
and really can cause the 1/100 difference as mentioned.
But if you remove the lenses, and it now between
the sensors of webcam or dslr and you are just
interested in the rings of saturns for example.
Both of them can image the rings assuming
they have the same pixels size or pixel scale.
Now the question is what bayer color implemnentation
is used for them? what noise suppression algorithm?
Can they be externally applied? A CCD is just a CCD
(or a CMOS is just a CMOS), so it's not far to imagine
cutting 1/6 of the cmos sensor in the canon eos and
using the 1/6 chip as sensor in the webcam. And becuase
of the lousy lens in the webcam, your excellent sensor
and lens become 1/100 worse than a dslr, gets so far?
Hughes
> > If webcam has 2/3 quality of
> > Canon, I can live with it. But it seems the quality
> > is lesser than 2/3. I wonder where I can see side
> > by side comparison of webcam CCD and Canon
> > EOS CCD like whether the Bayer color filters in
> > the former is half as bad as the Canon or 1/3
> > as bad.
>
> Good luck with that - I don't like your chances.
>
> --
> W
> . | ,. w , "Some people are alive only because
> \|/ \|/ it is illegal to kill them." Perna condita delenda est
> ---^----^---------------------------------------------------------------- Hide quoted text -
Bob Larter
> ? "Bob Larter" <bobby...@gmail.com> ?????? ??? ??????
> news:49f34284$1...@dnews.tpgi.com.au...
>> ASAAR wrote:
>>> On Sun, 26 Apr 2009 00:10:04 +1000, Bob Larter wrote:
>>>
>>>>> I wasn't aware of that when I wrote my reply. If he already has the
>>>>> Webcam, though, why is he now asking which is the best?
>>>> Damned if I know.
>>> It's to replace a portion of Hugh's damaged ocular implant, so
>>> only the best is good enough. Be wary and keep your distance or he
>>> may initiate the hive's assimilation process and as everyone knows,
>>> resistance is futile.
>> I'd quote Vogon poetry at you, but mercifully, I seem to have forgotten it
>> all.
> O freddled gruntbugly thy micturations are to me/
> As plurdled gabbleblotchits on a lurgid bee.
Gee, thanks a heap. ;^)
Bob Larter
No, it's not. It's because I'm an electronics engineer, & I know how
lousy the sensors in webcams are by comparison to DLSR sensors. For one
example, a webcam outputs less than 8 bits of intensity data per pixel,
whereas DSLRs output 12-14 bits per pixel. And there are many other
compromises in webcam images sensors that make them inferior to DSLR
sensors.
Hughes
Here is a photo I shot with the 1000mm telephoto with webcam.
http://www.pbase.com/image/111769165/original
original picture is located 3.8 meters from telephoto/webcam (scanned)
http://www.pbase.com/image/111769109/original
here is scanned image with zoomed portion of image
http://www.pbase.com/image/111769128/original
Measurement of actual picture is 7 inches horizontal,
5 inches vertical. Telephoto/Webcam located 3.8 meters
away shows an area of only 0.4 inches horizontal
(or only 5.7% of entire picture).
The webcam picture shows 0.15 degrees of picture
which is located at a distance of 3.8 meters.
Calculations:
Specs
4" aperture Telephoto 1000mm focal length f/10
webcam 1/4 inch CMOS 640 X 480 Sensor
picture area taken with telephoto/webcam is 10mm horizontal
at a distance of 3.8 meters hence
degrees of telephoto/webcam coverage = 2 x artcan (0.5 (10mm)/3800)
= 0.15 degrees or 540 arcseconds
resolving power of telephoto = 116 / 100mm = 1.16 arcsecond
pixel scale = 206265 (0.0057/1000)
= 1.185 arcsecond / pixel
Inquiries:
1. In the picture there is rectangular pattern taken with telephoto/
webcam,
what is it? Printing artifact of the brochure?
2. How come I can see vertical lines moving upward in the webcam
preview in the monitor? Noise or because image is dim??
3. Using micro photography, what specs so you can see the same
rectangular printing pattern in the picture of color brochure taken?
4. Using a DSLR, what would be the improvement in resolution and
colors provided dslr and webcam has same pixel pitch?
5. To be noise resistance, does the pixel (or sensel) have to be
at least 4.7 micron? How about 2 micron pixel pitch like in digicam.
Is there no possibility to construct 2 micron pixel pitch in the
future with
the same noisefree performance as present 6 micron DSLR? What
optical principles make it impossible? Something above wavelength
of light inpringing on the neighboring pixel or senses? Or what??
Thanks in advance for those who can answer so I can decide
whether to buy a canon 1000d or not. I need sufficient data
for complete analysis to make a decision to buy or not to buy
canon 1000d or not. Thanks.
Hughes
Bob Larter
> Here is a photo I shot with the 1000mm telephoto with webcam.
>
> http://www.pbase.com/image/111769165/original
I don't believe you. I think that photo was taken of a half-toned colour
image.
Hughes
> Hughes wrote:
> > Here is a photo I shot with the 1000mm telephoto with webcam.
>
> >http://www.pbase.com/image/111769165/original
>
> I don't believe you. I think that photo was taken of a half-toned colour
> image.
>
What? It was taken at a distance of 3.8 meters from the target
brochure with size of 7" horizontal, 5" vertical. Only the central
portion can be seen using the 1/2" 640x480 webcam sensor,
a Canon 1000D with 3888 x 2592 resolution can show
image 6 times larger.
I don't understand why you said you don't believe me and
you believe the picture was taken of a half-toned colour
image. You mean I print the scanned portion and take
picture of it 1X at 5 inches away? No. It was at 3.8 meters
away as indicated. The resolution is great because it was
a 4" aperture, telephoto used was the 4" Russian Rubinar
showned at:
http://www.kremlinoptics.com/catalog/item/rubinar_10_1000_telephoto_lens.html
Hu
Bob Larter
> On Apr 26, 11:06 pm, Bob Larter <bobbylar...@gmail.com> wrote:
>> Hughes wrote:
>>> Here is a photo I shot with the 1000mm telephoto with webcam.
>>> http://www.pbase.com/image/111769165/original
>> I don't believe you. I think that photo was taken of a half-toned colour
>> image.
>>
>
> What? It was taken at a distance of 3.8 meters from the target
> brochure with size of 7" horizontal, 5" vertical. Only the central
> portion can be seen using the 1/2" 640x480 webcam sensor,
> a Canon 1000D with 3888 x 2592 resolution can show
> image 6 times larger.
>
> I don't understand why you said you don't believe me and
> you believe the picture was taken of a half-toned colour
> image. You mean I print the scanned portion and take
> picture of it 1X at 5 inches away? No. It was at 3.8 meters
> away as indicated. The resolution is great because it was
> a 4" aperture, telephoto used was the 4" Russian Rubinar
> showned at:
Why on earth did you take a photo of a half-toned colour image?
For a better test, try photographing some text from the same brochure,
or something equally sharp.
Hughes
> Hughes wrote:
> > On Apr 26, 11:06 pm, Bob Larter <bobbylar...@gmail.com> wrote:
> >> Hughes wrote:
> >>> Here is a photo I shot with the 1000mm telephoto with webcam.
> >>>http://www.pbase.com/image/111769165/original
> >> I don't believe you. I think that photo was taken of a half-toned colour
> >> image.
>
> > What? It was taken at a distance of 3.8 meters from the target
> > brochure with size of 7" horizontal, 5" vertical. Only the central
> > portion can be seen using the 1/2" 640x480 webcam sensor,
> > a Canon 1000D with 3888 x 2592 resolution can show
> > image 6 times larger.
>
> > I don't understand why you said you don't believe me and
> > you believe the picture was taken of a half-toned colour
> > image. You mean I print the scanned portion and take
> > picture of it 1X at 5 inches away? No. It was at 3.8 meters
> > away as indicated. The resolution is great because it was
> > a 4" aperture, telephoto used was the 4" Russian Rubinar
> > showned at:
>
> Why on earth did you take a photo of a half-toned colour image?
> For a better test, try photographing some text from the same brochure,
> or something equally sharp.
>
I was trying to picture the colors via webcam to
see how DSLR greater color fidelity can wipe it
off the floor. That's when I saw the half-toned
which I can't see with the naked eye at 5"
which the telephoto/webcam can detect at 3.8
meters.
Anyway. I'm looking for resolution charts where
I can download and print in laser (or inkjet) and
use the lines per mm telephoto tests. If you know
where I can download it, let me know. Or do I
have to buy the charts completely printed by
a more superior machine and not home inkjet
or laser.. hmm.
Hu
> --
> W
> . | ,. w , "Some people are alive only because
> \|/ \|/ it is illegal to kill them." Perna condita delenda est
> ---^----^---------------------------------------------------------------- Hide quoted text -
Bob Larter
If you want to see that, photograph something natural, like a person, or
a flower.
> Anyway. I'm looking for resolution charts where
> I can download and print in laser (or inkjet) and
> use the lines per mm telephoto tests.
If you print a chart, it'll be cleaner if you use a laser, rather than
an inkjet.
> If you know
> where I can download it, let me know.
I'll see what I can find.
<Googles>
Here you go:
<http://www.graphics.cornell.edu/~westin/misc/res-chart.html>
Download the PDF version of the test chart & laser print it.
> Or do I
> have to buy the charts completely printed by
> a more superior machine and not home inkjet
> or laser.. hmm.
You can, but it'll cost you plenty of money! A laser printed version
should be fine for your purposes.
Tzortzakakis Dimitrios
? "Hughes" <eugen...@gmail.com> ?????? ??? ??????
news:8479d386-8227-4251...@y10g2000prc.googlegroups.com...
On Apr 26, 11:06 pm, Bob Larter <bobbylar...@gmail.com> wrote:
> Hughes wrote:
> > Here is a photo I shot with the 1000mm telephoto with webcam.
>
> >http://www.pbase.com/image/111769165/original
>
> I don't believe you. I think that photo was taken of a half-toned colour
> image.
>
What? It was taken at a distance of 3.8 meters from the target
brochure with size of 7" horizontal, 5" vertical. Only the central
portion can be seen using the 1/2" 640x480 webcam sensor,
a Canon 1000D with 3888 x 2592 resolution can show
image 6 times larger.
I don't understand why you said you don't believe me and
you believe the picture was taken of a half-toned colour
image. You mean I print the scanned portion and take
picture of it 1X at 5 inches away? No. It was at 3.8 meters
away as indicated. The resolution is great because it was
a 4" aperture, telephoto used was the 4" Russian Rubinar
showned at:
http://www.kremlinoptics.com/catalog/item/rubinar_10_1000_telephoto_lens.html
Hu
That seems quite a good lens, at $ 1300. I used to have a soviet TLR (120
film), an automatic Zenit, a manual Zenit... Although no comparison to my
Nikon FM-2.
In the meanwhile, see Leonid and Nikita's favourite tools:
www.esnips.com/web/dimtzortsphotos
Hughes
> ? "Hughes" <eugenhug...@gmail.com> ?????? ??? ??????news:8479d386-8227-4251...@y10g2000prc.googlegroups.com...
> On Apr 26, 11:06 pm, Bob Larter <bobbylar...@gmail.com> wrote:
>
> > Hughes wrote:
> > > Here is a photo I shot with the 1000mm telephoto with webcam.
>
> > >http://www.pbase.com/image/111769165/original
>
> > I don't believe you. I think that photo was taken of a half-toned colour
> > image.
>
> What? It was taken at a distance of 3.8 meters from the target
> brochure with size of 7" horizontal, 5" vertical. Only the central
> portion can be seen using the 1/2" 640x480 webcam sensor,
> a Canon 1000D with 3888 x 2592 resolution can show
> image 6 times larger.
>
> I don't understand why you said you don't believe me and
> you believe the picture was taken of a half-toned colour
> image. You mean I print the scanned portion and take
> picture of it 1X at 5 inches away? No. It was at 3.8 meters
> away as indicated. The resolution is great because it was
> a 4" aperture, telephoto used was the 4" Russian Rubinar
> showned at:
>
>
> Hu
>
> That seems quite a good lens, at $ 1300. I used to have a soviet TLR (120
> film), an automatic Zenit, a manual Zenit... Although no comparison to my
> Nikon FM-2.
> In the meanwhile, see Leonid and Nikita's favourite tools:www.esnips.com/web/dimtzortsphotos
>
Well I bought it for only $560 at www.lzos.ru See:
They are on sale. The $560 Astro-Rubinar set includes
two diagonals (relay system) and 3 eyepieces. It is
mirror though and I heard mirror telephoto has low
contrast. What is your (or others) experience on mirror
telephotos? But at least it can resolve not far from the
Canon 1200mm F/2.8 Telephoto (wonder when this
would be on sale too).
Hug
The Parade of Usenet Trolls Goes On
wrote:
You'll have to excuse all of these know-nothing resident trolls that are
replying to you. First of all, they don't even have a clue what an "airy
disk" is nor how it relates to maximum aperture size (NOT F-RATIO), they're
that clueless. You're asking for information to which they haven't educated
themselves yet, nor will they ever be able to. They're still trying to
comprehend the last camera manuals that they downloaded so they can pretend
to own those cameras and be experts on them. That's as close as they ever
get to any real cameras or optics.
I don't play with webcams but you're on the right track about their
resolution, dynamic range, and noise being equivalent to the same
pixel-pitch size of sensor from any DSLR using the same sensor type. Even
better performance if you chill the webcam sensor in many myriad of ways
(peltier stacks, etc.). The main difference is only in bit-depth in the RAW
data from a DSLR sensor (not its JPG output, which is only 8-bit, same as
any webcam). For pure resolution testing of your astronomical optics, which
doesn't care one squat about bit-depth in the image because even a 1-bit
depth is good enough for optics resolution tests, a good webcam sensor will
be all you need on small targets. You don't need the 12-14 bit RAW data.
But then these inexperienced usenet-living-trolls wouldn't know that and
don't even know what you are talking about, nor even begin to comprehend
what you are trying to accomplish. It's not that you're being unclear, it's
that you're throwing information at them that is *WAY*, *WAY*, beyond their
ability to reason from their usual pretend-photographer lives. The lives
that they live out on usenet and photo-forums while living in their
mommies' basements, pretending to be what they can never be. Heaven forbid
if you should show them how a $20 webcam can image as good as all the
DSLR's that they dream about owning. But alas, they can only download the
manuals, read, and pretend. Such is their sad and miserable lives.
Ignore them if they don't comprehend, because they never will. You can't
ask them a question where they have to reason for themselves. They have to
read the answer on an internet page somewhere else first before they can
continue to pretend to be the "x-spurts" that they claim to be while doling
out their worldly-wise sage photographer's advice (*not*). If they don't
read it elsewhere first then they can't parrot the information here with
their bird-sized brains. I bet they couldn't even put a spoon in their
mouths before Google came along to teach them how.
LOL! Whatta fucking joke they are! I love it when someone comes along and
asks a simple question that again reveals their stupidity and ignorance
caused by their lack of any real life and any real experience with using
real optics. You'd think they'd give it up since they've proved that they
are total fakes so often. But then, with this role-playing life being the
only life they've ever known, what else have they got?
LOL!!!!!!!!!!
Bob Larter
[...]
> LOL! Whatta fucking joke they are! I love it when someone comes along and
> asks a simple question that again reveals their stupidity and ignorance
> caused by their lack of any real life and any real experience with using
> real optics. You'd think they'd give it up since they've proved that they
> are total fakes so often. But then, with this role-playing life being the
> only life they've ever known, what else have they got?
Fuck off, troll.
Chris Malcolm
> The $560 Astro-Rubinar set includes
> two diagonals (relay system) and 3 eyepieces. It is
> mirror though and I heard mirror telephoto has low
> contrast.
Always advisable to use the eyes rather than the ears to check out
lenses :-)
> What is your (or others) experience on mirror
> telephotos?
The low contrast is often due to the shape making it more difficult to
control internal reflections and flare etc., in which case it improves
a lot with a really good long lens hood. In cheap ones it can also be
due to poor quality silvering, for which there is no fix.
--
Chris Malcolm
Rich
@mid.individual.net:
Silver isn't used anymore since only Perkin Elmer had a sufficiently good
(despite the Hubble mirror debacle) method for making sure the silver
coating didn't deteriorate quickly. Aluminum is used with multi-layer
dielectric coatings to avoid loss of reflection. Some aluminum coatings in
these telescopes are at 98-99%. Raw aluminum, without coatings is only 88%
reflective, so after 2 mirror surfaces, light throughput is down to 77%.
Then the central obstruction (secondary mirror) cuts out another 15%+.