[OM] Questar 700 reflex lens

Subject: [OM] Questar 700 reflex lens
From: usher99@xxxxxxx
Date: Fri, 11 Sep 2009 14:44:37 -0400
I was able to get one thanks to Jeff--had an OM T-mount adapter.?? :-)) I 
missed a couple snipes prior to that.? They seem to come up on yabe every 6-18 
mos or so.? The Op-tech hood gizmo is great when walking around with it or to 
store it.? I have a dew shield to use as a hood.? I use it as an a "bald eagle 
/various critter" lens.? Last Feb it was 10 deg and blowing and there was an 
eagle 20 yds away near the Chain bridge in Amesbury.? I had a super view but 
the wind was too much to get a sharp image.? It made for a reasonable spotting 
scope anyway though froze my butt off.

Thanks for the CAT design review.



That would be an interesting pair-up. The Celestron, being a Schmidt-Cassegrain 
design, should have a leg up on the Questar as regards coma since the Questar 
(like most small mirror lenses) is a Maksutov design. However, Celestron is a 
mass-market producer relative to Questar. Final finish and QC might trump the 
design advantage. Of course, coma is a function of fast optics so the superior 
design of the Celestron would already be under stress from the Questar being a 
slower optic. The Celestron should also suffer more from diffraction being a 
faster optic with a larger central obstruction. 

So, who has a Celestron 750mm f/6? I wish I did. My only Celestron is 2000mm 
f/10. I think the 750 f/6 probably hasn't been made for 30 years. 

Chuck Norcutt

usher99 [at] aol.com wrote:

Wonder about relative performance compared to the Celestron 750 F6. Focusing at 
F8 might be a challenge. 


But I recall that that lens is quite the performer. My spending priorities are 
elsewhere, but that price is reasonable considering the quality of the 
lens--minus the broken parts, of course.


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