Re: [APML] Hartmann Mask

[steve banbury <banburys@sonic.net>]

At 04:45 PM 1/5/04 +0200,  Teo wrote:
>Hello group, greetings from Greece!
>
>I have a Zenit SLR camera and a 250mm f/3.5 lens.My problem is that I can't 
>find every time the true infinite focus with absolute accuracy.Will a 
>Hartmann Mask solve my problem?I can't ''trust'' my eyes because I have 
>astigmatism and wear eyeglasses.What should I do??
>

Hi Teo--I had 'good' results with a 3 hole Hartman mask made by drilling holes
in a plastic lens cap.  I found a knife edge focusser (KEF) to be much more
accurate and in my experience more consistent when using my eyeglasses. 
It may be possible to purchase one for your camera from Hutech in California.

Good luck--Steve

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