Re: [APML] Mitsuboshi OAG (was: BRC Rosette)

[Matt BenDaniel <matt@starmatt.com>]

Chuck Vaughn wrote:
> 
> Matt,
> 
> > I would consider that OAG for my A-P refractor (2.7" focuser).
> > However the A-P field flattener needs to be a precise close distance to
> > the camera body opening.
> 
> I designed the FF lens into an OAG but that only works with a 35mm
> camera. The Pentax takes up all the extra distance and the prism would
> block part of the field anyway.
> 
> > Can the OAG be placed in front of that corrector?
> 
> Yes, but you'll have comatic stars for the guider.
> 
> > Would I need an extension tube to achieve focus on the ST-4?
> 
> Yes, a long one. Flexure of the extension tube will be a problem.
> 
> > Note that the new Traveler field flattener is very long.
> 
> I don't understand. The FF assembly is long?

Yes, it's about 3.5" long.  Even if it doesn't use up that much back
focus, imagine the following hanging off the focuser:
* Large-body OAG (e.g. Mituboshi).
* Autoguider head (on extension tube).
* Field flattener.
* Pentax 67 camera.
* Various cords, cables and hoses.
-- 
Matt BenDaniel
http://starmatt.com

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