I have looked at that scope too, and the forthcoming Askar FRA300.
Many refractor users catch the dreaded Aperture Fever and wake up with an emptier bank account and a 140mm triplet APO (and a burning need for an even better mount to carry it). I feel very lucky that I'm only suffering from a case of FOV Fever. The path to greater FOV leads to smaller, fast, decent refractors, with add-on or built-in focal reducers. I started my Journey with a 'C6', which turned out to be a C8. It was free. My first purchase was an 80ED, my next purchase was a 70ED. (I see a pattern here) The largest OTA I've looked at is the Askar FRA400, which has a little more FOV than the AT70ED with 0.8 focal reducer.
To treat my FOV Fever, I stare at this:
It shows the FOV for the 294MC (I have no plans for a larger camera, and spending a lot of money there has modest returns) with Reduced C8, Reduced 80ED, HyperStar C8, and reduced AT70ED. All of this I can do already. Where to from here?
Same diagram with seven possibilities with increasing FOV:
a. Askar FRA 300 native (60mm) ($950) - too expensive for moderate improvement
b. AT60ED + 0.8 reducer ($550) - go-to if I want this FOV
c. Askar FRA400 with 0.7 reducer (72mm) ($1450) expensive alternative if I also want aperture. The AT72EDII is off the list because of it's f/6 o.8 reducer combination being inadequately large.
d. SharpStar 61EFPH11 with 0.8 reducer ($700) OK for a modest improvement over the AT60.
e. Williams Optics RedCat 51 ($850) good quality, but small aperture
f. Askar FRA 300 with hypothetical 0.7 reducer (60mm) ($1200) worth considering if a reducer actually exists for this OTA.
g. Askar FMA 180 including reducer (40mm) ($400) need to wrap my mind around a 40mm aperture, but great guide, spotting scope, hugest FOV.
The optical and physical quality of all of the above is at least GOOD, for EAA, with a bit of CA in some circumstances with some OTA/Reducer combinations.
I've seen images of what the FMA 180 can do. FOV is over 6 x 4 degrees with the 294 camera, and I'm also planning to get a cooled mono version. At that price, I'm planning to get one, mostly to stop, or at least delay for a long time, other temptation.
Edited by SchoolMaster, 22 June 2022 - 04:31 AM.