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Old 6th September 2009, 07:04 PM
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Default Hoya R72 Filter

Hi,
I know that the filter R72 from Hoya is use with infrared film. Can someone tell me if they ever try that filter with ordinary black and white film like HP5+ or Tri-x? Is it worth the try or it is just a waste of film?
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Old 6th September 2009, 07:17 PM
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The R72 is specifically for I/R film and the 72 designation means it has a 720 nm rating (nothing lower than that passes throught it). If you hold a R72 up to the light and look through it you will be lucky to see anything unless you are looking at a very bright light source. This is approximately what a normal film will see also. Normal B&W white film cuts off well before 720 nm so all you will be doing is blocking recording light from the film. The chances are if you try using this filter with normal film is that your film will record nothing as the filter will filter out any light that is sensitive to the film. But by all means give it a go if you are in the mood for experimenting :-)

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Old 6th September 2009, 07:20 PM
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Surprisingly, it can work with some 'normal' b&w films - although the effect will not be the same as a proper IR film. The R72 filter filters out amost all light with a wavelength of less the 720nm. Most films will record some (but very little) far-red and infra-red light beyond this. Delta 3200 seems to work well, despite the graph on the Ilford data sheet showing no response above 740nm. Be aware, though, that your exposures will need to be very long (even with D3200). Start by working on the basis that the R72 filter will lose you at least 8 stops with normal film, and bracket widely. Worth experimenting with, though.

I'll try to dig out some negs I made a few years ago but never printed. Watch this space!

Rob

Last edited by Rob Archer; 6th September 2009 at 07:21 PM. Reason: I carnt splel
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Old 6th September 2009, 09:02 PM
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Thank you for the information. I will give it a try and Rob I will keep looking at the filters section. 8 stops should be a lot of fun!
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