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[OM] Re: Choosing a mirror lens [was Firmware for Canon Printer]

Subject: [OM] Re: Choosing a mirror lens [was Firmware for Canon Printer]
From: Jan Steinman <Jan@xxxxxxxxxxxxxx>
Date: Tue, 20 Feb 2007 21:37:25 -0800
> From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
>
> As to the apparent non-difference seen in the image sizes between the
> Bausch & Lomb and Celestron I speculate it may be due to the focusing
> mechanisms.  Some cat's focus by moving the primary mirror back and
> forth and this has the effect of varying the focal length and
> magnification for close objects vs. the specification for infinity.

Good call! The B&L moves the primary mirror, while the C90 moves the  
secondary mirror.

> Too bad you didn't get a chance to include the Zuiko 85-250/5 and  
> the C8
> 2000/10.  I don't own any of the glass that you tested but I do own an
> 85-250 and a C8.  I would hope that the C5 and C8 as Schmidt-Cat's
> (Celestron's claim to fame) could do better than the lower cost C90
> Maksutov.

I'm missing the C8. I used to have it set up in the living room,  
right off a deck where I could haul it out easily -- but we lived  
under a dozen 20 meter Doug fir trees, so the only viewing was in  
neighbor's windows... :-) We could read the marquee on a theatre  
about 10 km away, so we'd know if there was anything worth watching  
there!

Now we've got clear skies, near zero light pollution, and billion  
light-year views off the deck. I just need to talk my sweetie into  
making a waterproof dew bag for it, so I can do a proper polar  
alignment and fix the tripod right to the deck.

I find the C8 works much better as a lens with a 0.7 wide converter  
on it. That turns it into a 1000mm f7, which is bright enough for  
comfortable viewing.


:::: Express your individuality through brand-name conformity! ::::
:::: Jan Steinman http://www.VeggieVanGogh.com/::::



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