RE: Large format IR focus adjustment

["George L Smyth" <GLSmyth@xxxxxxx>]

> -----Original Message-----
> From: owner-infrared@xxxxx [mailto:owner-infrared@xxxxx]On Behalf Of
> Keith Davison
> Sent: Thursday, December 16, 1999 4:40 AM
> To: infrared@xxxxx
> Subject: Large format IR focus adjustment
>
>
> Is there a rule of thumb to estimate the IR focus shift when
> using large format
> cameras?  Something like "focus and then move the front standard forward
> by 0.x times the focal length of the lens"?

Yes, the adjustment is quite minor.  Advance the lens 1/4% of the focal
length.  Then means that for a 150mm lens, you'll increase the focal length
a little more than 1/3mm.

I generally shoot large format IR at f11-f16 and make no adjustments.

george

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

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