Webcam vs DSLR Target Field of View

Discussion in 'Digital Photography' started by Hughes, Apr 24, 2009.

  1. Hughes

    Hughes Guest

    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
     
    Hughes, Apr 24, 2009
    #1
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  2. Hughes

    Me Guest

    Hughes 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? 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

    Hughes.
    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.
     
    Me, Apr 24, 2009
    #2
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  3. Hughes

    Hughes Guest

    On Apr 24, 12:19 pm, Me <> wrote:
    > Hughes 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? 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

    >
    > Hughes.
    > 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.- Hide quoted text -
    >
    > - 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, Apr 24, 2009
    #3
  4. Hughes

    Hughes Guest

    On Apr 24, 12:33 pm, Hughes <> wrote:
    > On Apr 24, 12:19 pm, Me <> wrote:
    >
    >
    >
    >
    >
    > > Hughes 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? 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

    >
    > > Hughes.
    > > 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.- Hide quoted text -

    >
    > > - 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- Hide quoted text -
    >
    > - 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
     
    Hughes, Apr 24, 2009
    #4
  5. Hughes <> 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?

    jue
     
    Jürgen Exner, Apr 24, 2009
    #5
  6. Hughes

    Hughes Guest

    On Apr 24, 1:28 pm, Jürgen Exner <> wrote:
    > Hughes <> 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?
    >
    > jue


    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
     
    Hughes, Apr 24, 2009
    #6
  7. Hughes <> wrote:
    >On Apr 24, 1:28 pm, Jürgen Exner <> wrote:
    >> Hughes <> 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?

    >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
     
    Jürgen Exner, Apr 24, 2009
    #7
  8. Hughes

    Bob Larter Guest

    Hughes wrote:
    > 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
    ---^----^---------------------------------------------------------------
     
    Bob Larter, Apr 24, 2009
    #8
  9. Hughes

    Hughes Guest

    On Apr 24, 1:57 pm, Jürgen Exner <> wrote:
    > Hughes <> wrote:
    > >On Apr 24, 1:28 pm, Jürgen Exner <> wrote:
    > >> Hughes <> 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 -
    >
    > - Show quoted text -
     
    Hughes, Apr 24, 2009
    #9
  10. Hughes

    Hughes Guest

    On Apr 24, 2:34 pm, Hughes <> wrote:
    > On Apr 24, 1:57 pm, Jürgen Exner <> wrote:
    >
    >
    >
    >
    >
    > > Hughes <> wrote:
    > > >On Apr 24, 1:28 pm, Jürgen Exner <> wrote:
    > > >> Hughes <> 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 -

    >
    > > - Show quoted text -- Hide quoted text -

    >
    > - 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, Apr 24, 2009
    #10
  11. Hughes

    Hughes Guest

    On Apr 24, 3:42 pm, Hughes <> wrote:
    > On Apr 24, 2:34 pm, Hughes <> wrote:
    >
    >
    >
    >
    >
    > > On Apr 24, 1:57 pm, Jürgen Exner <> wrote:

    >
    > > > Hughes <> wrote:
    > > > >On Apr 24, 1:28 pm, Jürgen Exner <> wrote:
    > > > >> Hughes <> 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 -

    >
    > > > - Show quoted text -- Hide quoted text -

    >
    > > - 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.

    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

    > 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 -
    >
    > - Show quoted text -
     
    Hughes, Apr 24, 2009
    #11
  12. 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
     
    David J Taylor, Apr 24, 2009
    #12
  13. Hughes

    Hughes Guest

    On Apr 24, 4:50 pm, "David J Taylor" <-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 :)

    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
     
    Hughes, Apr 24, 2009
    #13
  14. Hughes wrote:
    []
    > 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
     
    David J Taylor, Apr 24, 2009
    #14
  15. Hughes

    ASAAR Guest

    On Fri, 24 Apr 2009 16:19:53 +1200, Me wrote:

    > 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.
     
    ASAAR, Apr 24, 2009
    #15
  16. Hughes

    whisky-dave Guest

    "Hughes" <> wrote in message
    news:...
    On Apr 24, 4:50 pm, "David J Taylor" <-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.
     
    whisky-dave, Apr 24, 2009
    #16
  17. Hughes

    Hughes Guest

    On Apr 24, 7:04 pm, ASAAR <> wrote:
    > On Fri, 24 Apr 2009 16:19:53 +1200, Me wrote:
    > > 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.


    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, Apr 24, 2009
    #17
  18. Hughes

    Hughes Guest

    On Apr 24, 7:08 pm, "whisky-dave" <> wrote:
    > "Hughes" <> wrote in message
    >
    > news:...
    > On Apr 24, 4:50 pm, "David J Taylor" <-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.


    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 -
    >
    > - Show quoted text -
     
    Hughes, Apr 24, 2009
    #18
  19. Hughes

    whisky-dave Guest

    "Hughes" <> wrote in message
    news:...
    On Apr 24, 7:08 pm, "whisky-dave" <> wrote:
    > "Hughes" <> 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 ?
     
    whisky-dave, Apr 24, 2009
    #19
  20. Hughes

    Savageduck Guest

    ASAAR wrote:
    > On Fri, 24 Apr 2009 16:19:53 +1200, Me wrote:
    >
    >> 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.
    >


    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 ****" 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
     
    Savageduck, Apr 24, 2009
    #20
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