RE: Presentation

[Russell Rosener <rrosener@xxxxxxxxxx>]

>Hello Russ:
>
>Why is lower then summer the film ISO in winter?
>And about focus, if I choose f/8 or smaller, that means focus increase
>togheter the depth of field, but, how can I know if the focus is exactly?
>Thanks
>Belén
>
>
There is stronger IR light during the summer, simply because of the 
fact that you are closer to the light source-the sun.
Yes, f/8 will give you more depth of field. To be precise, you need 
to have a focusing sacle engraved on the lens. Then you can shift it 
by the required amount by reading the barrel distance. I believe it 
is about 3 feet or 1 meter difference for IR film. I believe it would 
be 1 meter behind where your normal focus is, others on the list will 
have a more precise measurement.

Russ Rosener
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