Re: Refocusing for IR photography using Nikon ED glass lenses.

[George L Smyth <GLSmyth@xxxxxxx>]

Rolland Rainbow Elliott wrote:
> 
> Another question:  "Is there any relationship between the focal length of a
> lens and the need to perform an IR focusing adjustment?"  I ask this because
> the brochure that came with my Sigma 70-210 f/2.8D AF APO zoom lens  says
> that IR focusing adjustment is only needed at the short (70mm) end of the
> lens.

The shorter the focal length. the greater the depth of field.  The above sounds
backwards to me.

As I normally shoot with the lens stopped down to f11-f16, depth of field takes care
of everything and I do not refocus.

george

- -- 
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