Infra-red film or filter

medwaygreen

medwaygreen

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Richard
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Hi ,

I am thinking of trying infra-red,but,should it be by film or filter. I have seen that film is very light sensitive for loading and developing can be a problem as well with labs.

Is a filter the best option and depending on what type are the results as good?

Rich.
 
You need both Richard. The filter blocks light below the IR range and the film (usually*) has to be specifically sensitised for the IR wavelength.

*some films happen to be sensitive well above normal red, rollei retro for example but aren't quite true IR films.
 
Yep, as Steve has said, both are needed. This is because some "IR" films have a small band of sensitivity in the visible (towards the blue end, iirc?) as well, so blocking out this visible part of the spectrum to the film is required.
 
Thanks guys,

When you say,both,do you mean that when the film is loaded and set for the shot that you need to have a red,orange or some filter filter in front as well or do you mean a infra-red filter as well.
 
Yeah, you'd need to load up some IR sensitive film and then once you're finished composing you need to stick a R72 filter on the front. To your eyes the R72 is black as is blocks all the light in the visible spectrum but the film can see.

Might be a good job for a TLR actually, the number of times I've forgotten to add the filter...
 
steveo_mcg said:
Yeah, you'd need to load up some IR sensitive film and then once you're finished composing you need to stick a R72 filter on the front. To your eyes the R72 is black as is blocks all the light in the visible spectrum but the film can see.

Might be a good job for a TLR actually, the number of times I've forgotten to add the filter...
Click to expand...

Thanks for that ,looking for a R72 filter now, Does anyone know what the exposure compensation is for the R72?
 
medwaygreen said:
Does anyone know what the exposure compensation is for the R72?
Click to expand...

Its complicated. The published ISO is a guide under visible light and bears little resemblance to the sensitivity with the filter attached. I think the base ISO to use is low but I can't remember what it is exactly then bracket bracket.
 
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About 4-5 stops, you can't really measure IR light so you have to do an approximation. As most metering systems will not be able to meter through the filter you need to first meter with the filter off and then put the filter on and add the stops on.

Also you need to remember the focus shift as IR is slightly different from visible light. On most manual focus lenses you'll see a little focus mark past the usual one (e.g on Nikon lenses it's a red diamond), as you can't see through the filter you need to focus with it off and then adjust to the IR mark or use a small enough aperture for the depth of field to cover it.
 
medwaygreen said:
Does anyone know what the exposure compensation is for the R72?
Click to expand...

Take a meter reading without the filter on, set the camera manually to that exposure, then put the filter back on careful not to move the focus, then take your picture
 
I shot some Rollei ir 120 once, it was iso 12 with an r72, 400 without.
So I metered iso 25 with the camera, doubled the shutter speed, added the r72....Bob's yer uncle, Fred's yer aunt Fanny.

Worked for me anyway..:)
 
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