Re: SFX Question...

[George L Smyth <GLSmyth@xxxxxxx>]

C4N2H5O@xxxxxxx wrote:
> 
> How much, if any, focal compensation is needed when using SFX film?  Since it
> isn't "true" infrared, I'm assuming it isn't that much...

You needn't adjust the focus when using SFX, as the vast majority of the recording
will be in the visible range (assuming you are using a #25 filter).

> Also, since SFX only extends to about 750 nm, does anyone know how long of an
> exposure I'd need if I wanted to try it with a Wratten 89B or 88A?  Would it
> even be worth it or is that trying to get too much from this film?  Would it
> be best to stick with a filter with absorbtion limits at or below 680nm like
> a #70, #29 or #25?

Do some testing.  I've used a Hoya R72 filter (cuts at 720nm) with Fomapan 800 film
(a regular panchromatic film) and gotten an image (the film does have increased,
though not extended, red sensitivity).  Personally, I wouldn't think that this would
be the best film to bother doing this with, but it should be no big deal to expose a
handful of frames with the filter, bracketing further and further open.

george

- -- 
 Handmade Photographic Images     
  http://www2.ari.net/glsmyth/
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