IR camera filter

[LocksmithArmy]

the stats the I have been getting our of research (i have not played with the filters and whatnot yet) are about 1 in 20 people would be able to bee seen through... and 7 in 10 if ur at a beach...

most swimsuits are ir pass because they are trying to be uv pass so people dont have tanlines.

[Tygart]

WOW well I stand corrected. There is a whole other part of IR that I did not know about. Did not think it could be possible.

[HallisChalmers]

Jeez...I didn't know we had so many brainiacs on this forum....I'm amazed.

[elbowmacaroni]

the stats the I have been getting our of research (i have not played with the filters and whatnot yet) are about 1 in 20 people would be able to bee seen through... and 7 in 10 if ur at a beach...

most swimsuits are ir pass because they are trying to be uv pass so people dont have tanlines.

Yeah, I'd go with the 1 in 20... the weave could be loose enough on the fabric, or the fabric sheer enough in about that ratio... The beach figures make sense as well as wet clothing will pass more light of all spectrums.

The last statement is bunk... most swimsuits DO NOT try to pass UV, the ones that do are specialty items for the good 'ol s&m folks who enjoy having their willies sunburned... Okay, okay, while they may actually be a market segment who buys them, it really is the "I don't want tanlines" crowd who gets them.

[Violaetor]

I have a D40 with an R72 IR filter, the D40 has a very 'poor' low pass filter over the CCD which blocks only about 85-90% of infrared, and the IR filter in that range blocks about 95% of natural light, so net you are left with 5-10% infrared. The D40X has a much better ccd filter and leaves next to no IR spectrum in (if you have one don't waste the money on a filter).

Also there are real filters usually $50-150, and ALOT of just red glass, if it seems to good to be true, it probably is.

True infrared photography is only Black and white, never color... ever. Colored IR photos are a by-product of the most used technique to convert digital IR to the proper tonal range, which most people find appealing (peach/lavender/baby blue tones) so they leave it that way.

Also quite interesting is that the focal range of infrared light is about 8-12 inches closer to you than visible spectrum. So if you have your subject in focus and take a picture in infrared it will always be out of focus, which adds to the true ethereal feel of IR photography.

Think about that for a while, the infrared version of someone is standing closer to you than the real person...

Also as far as the whole x-ray thing goes, its pseudo accurate, but the more reflective an object is the more it will show in IR photos, so clothes which are more light absorbent/porus will allow the IR light to pass through to the more reflective skin/underwear which has a tighter "knit". Making it more visible under the right conditions, mainly VERY bright days with no cloud cover.

The best way to test your IR filter/camera is to go into a completely dark room, set your F/1.4-3.5 , SS to 10 seconds , then take a picture of your self going mental with your TV remote or similar pointed at the camera (pushing buttons obviously) observe the results, black image? you've been hornswaggled! crazy lines and dots of light? you got yourself a functioning IR camera!

[elbowmacaroni]

Yeah... another necro... but again, to an end. About all this seeing through clothes business with IR. Unless the fabirc is already sheer, in normal light or with a normal flash, all you're going to get is the clothing. HOWEVER, if and only if you are also illuminating the subject with a VERY strong IR source, you can see through SOME clothing and even then only sort of. It is more like a silhouette within the clothing as the clothing is still picked up but some can in that case make it through and back out. But it is nothing remarkable.

[echoplot]

I'd have to double check my facts, as it's been a while since I've played with that stuff...but I was pretty sure the ability to see through cloth with IR was primarily dependent upon the material (synthetics vs natural fibers).

Either way...I'd imagine that the effectiveness of a filter like that on a cell phone camera would, much the same as a typical DSLR, depend on the factory filter installed in front of the sensor. Most cameras have a hot mirror filter that is intended to block IR. They're never really 100% effective, but attaching an IR pass filter, in front of an IR blocking filter, would greatly increase the exposure time needed to allow enough IR spectrum photons to reach the sensor. That's why folks who want to shoot IR tend to remove the hot mirror and replace it with either a clear filter (full spectrum) or an IR pass.

For a neat experiment though, if you'd like to check the quality of the hot mirror filter on your phone's camera, stand in a room with no (or dim) lighting, point a television remote at your lens and press a button. You'll see more or less light with different model cameras. It's also useful for locating IR light sources (and often the camera itself) for cctv cameras intended for night time surveillance.