IR filter + IR-only camera Results in normal shutter speeds?

[Markw]

Okay, so I've been messing around with a 720nm IR filter on my D300s. Needless to say, it's quite miserable. I have just come into some money and am considering purchasing an IR-only DSLR. I was wondering if, since the IR-blocking filter has been removed from the camera, if the camera is converted to 720nm, but a 830nm filter is put on it, if the shutter speed will still be normal as if there was no filter on the lens because the filter on the sensor has been removed?

Sorry if that sounds confusing..
Mark

 

[Garbz]

Not quite. You're still blocking all the visible light which would normally contribute to the image and you only gain a small part of the IR spectrum in return. That said while you won't have "normal" shutter speeds you do have shutterspeeds that very easily well into the handheld realm, that small part of the IR spectrum is actually quite bright.

Your typical 720nm will have a roughly 3 stop loss for a well vegetated scene. Probably 2 stops for beach or snow.
A deeper filter like a Hoya RM90 will give you 4-5 stop loss for vegetation and 3ish for snow or beach.