After seeing Fillmore's IR photos of Epcot, it makes me want to shoot IR myself. ; So I have a couple of questions. ; After doing a little "googling" I found a few sites that say some digital cameras are able to pick up IR out of the box and not need a "conversion". ; Initially it said that the easy way to test this was to point an IR remote at the camera and see if it picks up a white light when a button is pressed. ; I also found out that the Sony "Nightshot" that is on my camera (DSC-H50) is actually using IR (although when used the photos look more like NightVision Goggles) in "No Light" situations. ; So my question is this... Since the Nightshot allows the sensors to pick up IR, does this mean I could purchase an IR filter and start shooting or would I still need a converted camera? ; I obviously do not want to invest in the filter if it isn't going to work. ; Any information/ advice is greatly appreciated.
I suspect you'll need to ask this on some other forums where there are a lot more hardware geeks. But if you do find more info, please repost it here. Erich
Okay, forgive me if this is needlessly long winded or technical, but I kind of want to establish some basic information here to try to make sure we're all operating on the same page here. First off, when we're talking IR photography we are generally talking about near IR, as opposed to far IR. ; Far IR is where you get into thermal vision systems, cameras that see objects in terms of their surface temperature rather than reflected light. ; Near IR is still reflected light, it's just at a frequency beyond what we can normally see. ; I say normally because I've seen it suggested that if we wore sunglasses that were IR pass filters (filters that blocked visible light but let near IR pass through) it might be possible for human eye to see the world in near IR. ; I haven't seen this verified though. Next step, what this means to digital cameras. ; The interesting thing is that the CMOS and CCD sensors used in cameras are sensitive to near IR. ; And this is normally a problem because they'd be receiving light that we typically don't see and the resulting picture would be a little weird. ; So most cameras have what's referred to as a hot mirror over the sensor, I don't know the specifics of how it works but it's basically a filter that blocks (or perhaps as suggested by the name, reflects) out the normally unwanted near IR light and lets visible frequencies pass through. To do near IR photography with a camera you slap another kind of IR filter onto your lens. ; This time you're blocking out visible light and are letting near IR light pass through. ; You can find different kinds of filters with different cutoff points and adjust exactly what frequencies you're letting. ; But basically you're making it so that all your camera can see is near IR. ; If your camera has a strong IR blocking filter then this means you have to take very long exposures to get enough light through, if it has a weaker filter then you have it a bit easier. ; If you have a modified camera with no blocking filter all the better. Sony cameras enter the picture because of the already mentioned nightshot mode, which typically seems to remove the IR blocking filter altogether. ; This makes colors weird but lets the camera receive extra light that would normally be blocked. ; It can be tied with an IR illuminator, a near IR LED that's kind of like a nearly invisible floodlight that only the IR sensitive camera can see. ; That is what really makes nightshot work in darkness, the extra sensitivity from removing the filter only gets a bit more light otherwise. ; The LED lets the camera see in otherwise total darkness and is only visible as a dim red glow to human eyes (the light itself glows, you can't see it reflecting off of other things at all). But there's a problem. ; A while back there was a hubbub about people using nightshot camcorders with IR pass filters to see through certain types of clothing surreptitiously. ; Basically some clothing appears somewhat transparent when viewed in near IR light. ; Sony responded to this by changing their nightshot systems to be somewhat more restrictive, I don't really know how. ; I found a blog post that seemed to suggest that the nightshot exposure modes are crippled to the point where they overexpose the image unless you're working in very dark conditions, you simply can't use faster shutter speeds or that sort of thing. ; You've already got the camera so you can check this out, can you go into nightshot mode in the daytime and adjust exposure to still take an acceptable picture? The blog suggested use of neutral density filters on top of the usual IR pass filter to further cut down on the light received until it was low enough to not overexpose when using the exposure settings that the camera forces you to use, if that is the case for you. This is merely the results of ten seconds googling, I don't have personal experience with these cameras, I've only used nightshot camcorders and haven't tried putting an IR pass filter on them. ; I'm starting to think about it now though.. IR video. ; Why not? ; I'd need such a tiny filter it should be comparatively cheap, if I can find one that small at all... But to attempt to summarize.. it seems that yes, you could pick up an IR blocking filter (and maybe a selection of ND filters if that part of the blog post I read proves accurate), maybe also tape over the IR emitters if you can't turn them off in a camera function, and have a reasonably good IR photography system without having to muck about with multiple minute long exposures or camera modifications. I kind of want to stress that even if you didn't have nightshot you wouldn't HAVE to pull the hot mirror off the sensor. ; Even cameras that have strong IR filters can still be used for IR photography so long as you're willing to put them on a tripod and use minutes long exposures. ; I found a post by someone saying that if he was shooting a scene that would normally use a 1/2000th of a second exposure he'd end up having to exposure for 8 minutes. ; I think he was using my camera, so I'm probably looking at that kind of penalty if I want to get into IR without, shall we say, voiding my camera's warranty in a big way. ; This is certainly less than ideal, but I could still at least start playing with IR landscapes and such.
Wow, that's a lot of information... but very helpful. ; Might have to take my camera to the Photo Store and see if they will let me try out their filters before making a purchase (rather than purchasing online and having to mail back a return). ; Thanks for the very useful info.
So I did what I probably should have done last night before posting all that I did.. I googled H50 and IR. It sounds like you are going to have a limitation of only using a shutter speed of 1/30s and whatever the widest aperture setting you have available for your given zoom. ; It may also make the picture green. ; You can test this easily enough, just go outside and try to take pictures in nightshot mode in full daylight. ; However your camera behaves is what you'd be stuck with if you slapped an IR filter on it. ; If the camera refuses to expose properly and overexposes everything then you're probably going to have to use ND filters to manually correct the exposure. ; Take note of whatever limitations it imposes on you. ; Are you missing any favorite modes or special features? ; It's up to you to decide if any of that is a deal breaker. So far I've found a hardware modification that will make it so that when you turn nightshot on the camera doesn't know you've done it. ; Overall I don't recommend it unless you're used to working with intricate mechanisms, including being willing to either properly discharge the flash capacitor or risking accidentally discharging it into your body. ; It sounds like the dis-assembly is the hardest part, others reported breaking components when they tried to take it apart. ; But here's a link to it. ; At least it includes a few sample IR pictures. http://forums.dpreview.com/forums/readf ... 9+mod&qf=m It's not entirely clear in that post, but in the author's earlier post on the H9 he shows what he did. ; The only modification is actually covering up one pin on the ribbon cable with electrical tape. ; The hard part is just getting the camera opened up enough to allow access to it. I also found this series of blog postings about IR photography with the apparently closely related H9. http://irbuzz.blogspot.com/2007/06/revi ... sc-h9.html The sample pictures are missing, but it goes into more depth about the various limitations and some attempts to deal with them, including the ND filters that I suspect you'll need to use. ; Also note that it appears to not be capable of producing color IR pictures. ; Monochrome IR is fine, but I'm just saying if you had your heart set on producing those surreal alien false color IR landscapes you may be disappointed.
