I asked for IR, I didnt know full spectrum was an option. But I was specifically told I would still need to use an infra red filter on the lens as all that is done with an IR conversion is to remove the IR cut filter, and re calibrate the focus for IR - or so i believe
thus to get the B/W IR effect I was after you would still need to use and IR filter.
Not really "IR." Your camera is now full-spectrum, and capable of IR, but it's not quite the same. My IR cameras are all fully modified so that I do not need to use a filter; the IR filter is installed atop the CMOS/CCD itself, allowing for me to compose the scene without constantly removing/reinstalling a filter.
"Also, I'm speculative that the TTL metering might not be metering "non-visible" parts of the spectrum. Thus, when you place the IR filter over the lens, it just treats it as if it were a thick ND filter, and adjusts the exposure as if it were only dealing with visible light."
Do you think that is what has happened?, but surely a thick ND filter should dramatically reduce exposure time? I use a 10 stop ND on my P25+ and yes the metering is off but the exposure time is reduced not increased
Yep, I think that's what's happened.
Your camera is now sensitive to IR light, while it wasn't before. The R72 will behave similarly to an ND filter on a camera with an IR-blocking filter over the CCD/CMOS. However, now that your camera's IR-blocking filter has been removed, the R72 filter is only filtering wavelengths less than 720nm.
"I've done both full-spectrum, and fully converted IR,"
with P1, or another brand?
Canon, predominantly. However, the science behind this is essentially universally applicable.
Im not really worried about the metering, just that the P21+ base iso is 100 so if you like to shoot at f8 or f11 on a bright sunny day you might soon run out of shutter speed options....dont really want to add ND filters too!
Mike