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11/30/2005 10:52:16 PM · #1 |
Hi, how do we know if a camera can take IR photos or not?
I know not all cameras are capable, even with an IR filter added. Thanks |
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11/30/2005 10:54:58 PM · #2 |
| dumb question: What is an IR photo? |
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11/30/2005 10:55:30 PM · #3 |
Originally posted by crayon:
Hi, how do we know if a camera can take IR photos or not?
I know not all cameras are capable, even with an IR filter added. Thanks |
The quick and dirty way is to look at the LCD while pointing a TV remote at the lens and pushing a button. If you see a light, then the camera can see IR.
For more sophisticated methods, Google is your friend.
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11/30/2005 10:58:25 PM · #4 |
Originally posted by AzCKelly:
dumb question: What is an IR photo? |
infrared |
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11/30/2005 11:55:39 PM · #5 |
IR photography is easier to take with a non-dSLR camera because you can see what you are focusing on before you snap the shot.
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12/01/2005 12:52:18 AM · #6 |
Originally posted by faidoi:
IR photography is easier to take with a non-dSLR camera because you can see what you are focusing on before you snap the shot. |
Hi Faidoi, please can you explain more? I dont understand why a dSLR cant see what it is focusing on before we snap? I'm new and willing to learn. Thanks. |
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12/01/2005 12:57:27 AM · #7 |
a dSLR camera doesn't show you the scene through the sensor like most non-dSLR cameras. Using your LCD display, you can see what the snesor see, instead of only the visible light your eye sees.
If you have an IR filter in front of a lens on a dSLR and try to look through the viewfinder, your eye won't see very much, if anything, because you can't see near-infrared light.
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12/01/2005 01:10:20 AM · #8 |
To clear that last one up. SLR cameras have a set of lenses, a prism (sometimes replaced with a set of mirrors) and a flipping mirror to form an optical path from the rear viewfinder through the lens.
Message edited by author 2005-12-01 01:12:33. |
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12/01/2005 01:22:54 AM · #9 |
| Got it. But cant a dSLR user see what the sensor sees by means of the external LCD display? You can compose photos using the external LCD, cant you? If you can, wouldnt that show the IR effect? |
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12/01/2005 01:25:26 AM · #10 |
if your dSLR allows you to compose through the LCD panel then yes, you can compose/shoot IR through the viewfinder.
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12/01/2005 03:51:00 AM · #11 |
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12/01/2005 04:28:49 AM · #12 |
Originally posted by crayon:
Got it. But cant a dSLR user see what the sensor sees by means of the external LCD display? You can compose photos using the external LCD, cant you? If you can, wouldnt that show the IR effect? |
No dSLR usually do not allow composition via the sensor and lcd. A mirror sits in front of the sensor and directs lifgt up into the view finder prism. When the shutter is released the mirror flips up out of the way.
Message edited by author 2005-12-01 04:29:04.
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12/01/2005 04:35:28 AM · #13 |
Originally posted by Falc:
No dSLR usually do not allow composition via the sensor and lcd. A mirror sits in front of the sensor and directs lifgt up into the view finder prism. When the shutter is released the mirror flips up out of the way. |
Not really important, but in a design point of view, is that a good thing, or a weakness? Isnt that the same as having an optical viewfinder with 100% coverage? So does the SLR's viewfinder shows digital information like histogram, etc while composing a shot? Many thanks. |
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12/01/2005 04:42:25 AM · #14 |
Originally posted by crayon:
Originally posted by Falc:
No dSLR usually do not allow composition via the sensor and lcd. A mirror sits in front of the sensor and directs lifgt up into the view finder prism. When the shutter is released the mirror flips up out of the way. |
Not really important, but in a design point of view, is that a good thing, or a weakness? Isnt that the same as having an optical viewfinder with 100% coverage? So does the SLR's viewfinder shows digital information like histogram, etc while composing a shot? Many thanks. |
Ther is no digital info apart from light meter and focus indicators in a dSLR viewfinder - because the sensor is not engaged at that point so can't build a histogram.
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12/01/2005 08:12:16 AM · #15 |
Another issue for digitial IR photography is the sensitivity of the sensor. Due to the hot-mirror filter in front of the sensor, infrared light is bounced away from hitting the sensor and prevents IR light from degrading the image. Because the filter is not completely efficient in it's job and allows some of the IR light to reach the sensor, we can record IR images if the visible light spectrum is blocked from reaching the sensor. This is what an IR filter that you put in front of your lens does...blocks visible light to different degrees with differnt strength filters, and allows IR light to flow through. However, because only a little bit of the IR light is trickling through the hot-mirror filter, long shutter speeds are required to make an image.
The Sony 707 digicam was very good for IR photography because it has a hot filter that was removeable from the light path (done in camera). Other cameras notable for good IR response are the Nikon 995 and Olympus C-5050 and C-2100 (probably because their hot filters are not so strong). As a matter of fact, when I put a IR filter in front of the lens of my c-2100 I get hand-holdable shutter speeds of 1/30th second, whereas with most cameras you have to mount your camera on a tripod and use shutter speeds in the 4 second range.
Another very good camera to use for IR is the DSLR-like Olympus E-10 and E-20 cameras. Because they do not have pentaprism viewfinders but instead use a prism that seperates the light into two different paths...one going to the sensor, and the other going to the viewfinder, you can use the LCD screen for viewing the scene and focusing when composing the shot. So far, the cameras I have mentioned above are all older models. Of the newer cameras available today, the ones I know to be quite sensitive to IR light are the Pentax ist* DS and Olympus E-300 and E-500, though you won't be able to use the LCD screen with them because they have the more common pentaprism style viewfinder. Actually, in the case of the E-300, it uses a porro viewfinder (pretty much the same as a regular pentaprism, but it reflects the light up to the sensor in a sideways path, instead of the upward path of a regular pentaprism.
For a listing of the sensitivity of different cameras to IR light see this web site.
Message edited by author 2005-12-01 08:18:33. |
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12/01/2005 08:53:47 AM · #16 |
There are people who will refit your DSLR with a less aggressive hot mirror to allow for enhanced IR sensitivity. If you're brave, there are some sites that give you a guideline on how to do it yourself.
Canon also makes a 20Da for astrophotography that has a hot mirror that passes significantly more IR as well. I have not seen any images from that cam being used for terrestrial IR photography.
Either one of these options would be great for IR photography but the camera would not be very good for conventional photography.
Message edited by author 2005-12-01 08:55:19.
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