Re: [APML] Proper Use of Varimagni Finder

[Matt BenDaniel <matt@starmatt.com>]

I agree. I tried the Varimagni. Its magnification is only 2.5x, whereas you probably want 20x. Plus, if you examine the unit you'll see that its aperture is quite restricted, which makes stars very dim. I sold mine. 

I've been using knife edge focusing for two years for telescopic astrophotography, and I believe it is the best possible method. 

Almost all of my Olympus and Pentax 67 lenses seems to be well focused at the infinity stop. 

I agree with Torsten's focus test approach.

Matt

At 01:03 PM 6/15/2002 -0700, R Torsten Clay wrote:
>I have found that the varimagni finder is pretty much useless for 
>astrophoto focusing- not enough magnification. For focusing piggyback 
>shots, I just set the lenses at infinity. 
>
>You can determine if the infinity mark is accurate by attaching tape with
>many small marks (ie a ruler scale) to the lens and making a series of
>test exposures with a stationary tripod, each time moving the focus
>slightly. Then just use the mark that gives the thinnest line on the test
>shot.
>
>Torsten
>
>On Sat, 15 Jun 2002, Kevin Wigell wrote:
>
>> I just received a Varimagni finder for my Olympus OM-1. I bought it to
>> improve my ability to focus when I have the OM-1 mounted piggyback on my
>> scope and using a 50 mm or telephoto lens (I use a KEF for focusing through
>> the scope). I've been having great trouble getting good, consistent focus
>> with lenses on the camera.
>> 
>> I'd appreciate any advice for using the Varimagni to focus the lens. I've
>> practiced with it during the day on terrestrial objects, but focusing on
>> stars is completely different, as we all know. BTW, I have a Beattie screen
>> in the camera. Do I just focus with the Varimagni at its highest
>> magnification setting (2.5x) until the stars look the sharpest, or is there
>> more to it than that? Normally I photograph one f/stop higher than the
>> lens's wide open setting.
>> 
>> Thanks,
>> Kevin Wigell
>> 
>> 
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>
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--
Matt BenDaniel
matt@starmatt.com
http://starmatt.com


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