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Infrared - 20D

Forums > Digital cameras > Infrared - 20D

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    derekm
    7
    34 forum posts
    31 Aug 2005 - 3:02 AM
    0

    Has anyone tried using an IR filter with the 20D? When I tried a friend of mine's filter I had to use ridiculously long exposure times to get even the faintest image i.e. 2 minutes.

    Has this something to do with the way digitals filter out IR?

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    conrad
    conrad (e2 Member)
    8
    10712 forum postsconrad vcard 113 Constructive Critique Points
    31 Aug 2005 - 3:07 AM
    0

    Yes. Yes. See yesterday's thread here and my upload of today here - it's far from perfect, but it's an example. I used 30 seconds - on a very bright afternoon.

    Conrad

    goatster
    31 Aug 2005 - 3:07 AM
    0

    yes, exposure times of around 25 secs on a bright day will do.

    Tony

    derekm
    7
    34 forum posts
    31 Aug 2005 - 3:30 AM
    0

    Thanks. I'll have to investigate further. The notion of what the camera body was made of hadn't occurred to me, but it does make sense. I've seen on the Canon website the 20D IR variant which is designed for astronomical use, but having just purchased my 20D a couple of months ago, my bank manager might complain if I asked for a new one!

    I've done quite a lot of work using Photoshop to generate faux IR effects in B&W and it's pretty effective, but am curious to see if I can get similar results in the camera.

    conrad
    conrad (e2 Member)
    8
    10712 forum postsconrad vcard 113 Constructive Critique Points
    31 Aug 2005 - 3:36 AM
    0

    I have to correct you here, the remarks about the metal camera body apply to IR film only - it's totally irrelevant for digital users.

    Have a look here for the explanation of hot mirrors and how they block IR light in DSLR cameras.

    I suspect that it's blocked quite strongly in the 20D, since Canon saw it fit to bring out the special IR version you mention. Which is why you and I need longer exposure times to get what we want than other digital or even film users.

    But two minutes is a bit long. What ISO were you using, and how much light was there?

    Conrad

    goatster
    31 Aug 2005 - 4:02 AM
    0

    Just thought I would add one...

    20d IR photo

    Tony

    conrad
    conrad (e2 Member)
    8
    10712 forum postsconrad vcard 113 Constructive Critique Points
    31 Aug 2005 - 4:06 AM
    0

    Now there's an excellent example! Thanks for sharing that!

    Conrad

    derekm
    7
    34 forum posts
    31 Aug 2005 - 4:26 AM
    0

    I was using ISO 100 and it was late afternoon (but on a sunny day). My friend has the Nikon D50 and she was able to get passable images of the same scene with 20 sec exposures.

    conrad
    conrad (e2 Member)
    8
    10712 forum postsconrad vcard 113 Constructive Critique Points
    31 Aug 2005 - 4:38 AM
    0

    Your need for a 2 minute exposure still puzzles me, but you should indeed need a longer exposure than a Nikon user.

    Conrad

    digicammad
    digicammad (e2 Member)
    9
    21917 forum postsdigicammad vcard United Kingdom37 Constructive Critique Points
    31 Aug 2005 - 4:54 AM
    0

    The iso difference would have entailed you using double the length of exposure. Were you using the same aperture as your friend?

    Ian

    stuwhitt
    31 Aug 2005 - 5:29 AM
    0

    This was taken by myself using a Hoya R72 filter at F5.6 for 2 seconds on my 300D, presumably the 20D has a similar strength anti aliasing filter, so acceptable results should be achievable using similar settings.
    When I took this shot I did not even meter the scene, I used 2 seconds @ F5.6 after much experimentation and helpful advice, from members here on EPZ, check out proberts portfolio for inspiration

    Stu

    goatster
    31 Aug 2005 - 8:47 AM
    0

    Stu,

    you dont mention what ISO you used, but at 2 secs 5.6 on a bright day the 20d would not give you any image at all, 30 secs is ok down to 20ish on a bright day. ISO 100.

    Tony

    stuwhitt
    1 Sep 2005 - 10:39 AM
    0

    Hi Tony

    Sorry for the delay in replying, it was shot at ISO 200, so it looks like the filter on the 20D is a lot stronger than that on the 300D which is probably one of the reasons that images taken using the 20D show superior sharpness

    Stu

    derekm ... the thing to do is to point your TV remote at the camera and press the buttons on it ... If you can see anything you should be able to shoot IR but the brighter the signal from the remote the better the camera is.

    If you are really keen you remove the camera's filter and replace it with an IR ...one Canadian Fine Art photog got Nikon Canada to do this to one of his D70's and he gets relatively 'normal' exposures with it.

    There are IR filters and IR filters which let no visible light through and others which give you a reddish cast to your results. The latter must be letting in more light with shorter exposure times I guess. Since the Canadian has removed the bayer filter he can use a filter with a lower cut-off point to get the normal exposures ... mine are normally in the one or two seconds wide open [f/2.8]in bright conditions. [Nikon 5700][Pana FZ20 .. not a peep so no good at all :-( ]

    snapbandit
    snapbandit (e2 Member)
    9
    2188 forum postssnapbandit vcard Northern Ireland3 Constructive Critique Points
    1 Sep 2005 - 3:21 PM
    0


    Quote: the thing to do is to point your TV remote at the camera and press the buttons on it ... If you can see anything you should be able to shoot IR but the brighter the signal from the remote the better the camera is.


    forgive me if I have missed something as I've only scanned over the thread, but surely this only works with an electronic viewfinder?, DSLR's have optical viewfinders, so you would need to take a pic & study the review screen.

    Joe B

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