Re: [ap-ug] M33 with 92mm Stowaway, combining RGB, H-alpha, and O-III

Dale Ghent

It’s something I would be interested in, and I don’t even have a Stowaway. I have a CFF 92 f/6 refractor and the M63 APM-Riccardi reducer that have been using on it is baaaaarely passable, with some leniency,  when using it with my APS-C sensor. I’m using an OAG with this scope since it’s a compact travel imager, so its pick-off mirror is definitely sitting outside the corrected area in order to avoid intruding into the sensor’s fov. A larger corrected field is certainty something that I miss and would jump at the opportunity to have, even if it meant a focuser upgrade (my CFF 92 came with a 3” FTF; an improved optical design similar to the M63 format or a little larger, would be fine in my case.)

The APS-C Sony IMX571 sensor that is now in many CMOS astrocams is a fantastic sensor and is fairly accessible in terms of price, which is fueling its rise as a common sensor to see now. It’s the smaller cousin of the full-frame IMX455 which is also popular, of course.  A TCC and flattener that could competently handle both would be noticed. Other makes of (mainly Chinese) refractors in the 90-110mm range also lack a competent reducer/flattener for these sensor sizes and one could find use with those. 

On Dec 11, 2021, at 19:33, Roland Christen via <chris1011@...> wrote:

It's certainly possible to design and build a super sharp telecompressor for the 92 Stowaway to cover the full frame CMOS cameras with sharp round stars into the corners with no vignetting. It would require 3 things, a more exotic compressor design, a larger focuser and market for it. It would be more or less a super astrograph, rather than a small fun portable scope, plus it would cost more. Is the interest there or not, that is the question.


-----Original Message-----
From: Roland Christen via <chris1011@...>
To: <>
Sent: Sat, Dec 11, 2021 6:15 pm
Subject: Re: [ap-ug] M33 with 92mm Stowaway, combining RGB, H-alpha, and O-III

Tonight I'm shooting in very clear skies, very cold sub-freezing, but poor seeing. Moon is also nearby.


-----Original Message-----
From: Eric Weiner <weinere@...>
Sent: Sat, Dec 11, 2021 6:09 pm
Subject: Re: [ap-ug] M33 with 92mm Stowaway, combining RGB, H-alpha, and O-III

Thanks Roland. I have the 92FF as well.  Just exploring my options. Focal length of 644 vs 488, a 1’x0.7’ delta. That’s worth the trouble of flats for some targets imho. Our skies in Colorado have been terrible so I haven’t had a chance to experiment with the TCC myself yet. I just got it on Monday. 


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