TheSkySearchers

I'm a relative novice in the dark arts, and recently bought a Fornax LT2 tracker, which I am rather pleased with. I also have an ASAI Air pro for PA and guiding, although I don't need guiding with the LT2 at the moment

I currently use DSLR's (D5600 and D610) with a Samyang 135mm and an Askar FMA 180. I'd like to add a ¬ 60mm refractor to this line up to give me a longer reach, but not exceed the mount capability or ability to target DSO's.

The Samyang 135 is excellent. The Askar introduced me to the delights of getting backfocus nailed and dealing with blue bloat, although I think I have this sorted out now.

For a longer reach I've been considering the following, for use with the D5600 cropped sensor:

Redcat 51 petzval (but the spotty QC is putting me off, as returning scopes from KSA is a major undertaking)

Vixen FL55 SS with flattener/reducer (I think this is a perfect match for the Fornax, there are some very nice Astrobin examples taken with this, and I don't mind paying for good quality, but I'm not sure if coma is a problem or not with this)

TS 70mm F5 quad flatfield APO, which appears to be a great scope (this may however be too large for the Fornax, although I have a counterbalance set up)

TS PhotoLine 60 mm f/6 FPL53 Apo doublet with flattener (unless CA is significant.. it's a problem on the Askar FMA 180)

TS 62 mm f/4.8 Quintuplet Flatfield Apo (looks like an all in one solution)

For my particular circumstances, I'd prefer to buy once and have a scope I can keep for a while, with no real CA, a sharp image, a good image circle and a flat field, with good QC from the supplier. The ability to use it with the FF D610 would be a bonus even if oversampled.

I welcome the views from the more experienced star gazers here, given the above

My Fornax set up with a vixen counterbalance and some pan heads for RA and Dec adjustment

Ok I'll make it simpler. Redcat 51 or Vixen FL55ss?

I have the Redcat51 and am blown away by the quality of the build and the images. The field is super flat so no FF needed, as oppose to the FL55ss. It has a Bahtinov mask built into the cover and a camera rotator. The focuser is helical. The camera is screwed into place, as opposed to using a focuser tube with screws that can have play and cause tilt or an offset. Both have fluorite glass (synthetic for the RC). The focuser can be locked. The light/dew shield is long and is screwed on. It feels rock solid. Check what rings you need when you buy it. The optics are very sharp and the colors are beautiful. Here's a review that I support (there are many reviews on the www), https://astrobackyard.com/william-optics-redcat-51/ .

SkyHiker wrote: ↑Mon Oct 11, 2021 1:40 pm I have the Redcat51 and am blown away by the quality of the build and the images. The field is super flat so no FF needed, as oppose to the FL55ss. It has a Bahtinov mask built into the cover and a camera rotator. The focuser is helical. The camera is screwed into place, as opposed to using a focuser tube with screws that can have play and cause tilt or an offset. Both have fluorite glass (synthetic for the RC). The focuser can be locked. The light/dew shield is long and is screwed on. It feels rock solid. Check what rings you need when you buy it. The optics are very sharp and the colors are beautiful. Here's a review that I support (there are many reviews on the www), https://astrobackyard.com/william-optics-redcat-51/ .

Hi Skyhiker and thanks for the reply.

The Redcat looks great but the reports I have read seem to indicate some spotty QC with quite a few users getting miscollimated scopes or flat field issues, which I guess is a risk with a Petzval design. Looks a great scope if you get a good one though. A very nice design ethos seems to run through WO gear.

I think the Vixen is likely to have a high level of QC so the odds of getting a good one are better, but it is twice as expensive and appears to have some coma at the field edge, plus getting backspacing spot on seems essential. CA appears to be non existent and center - mid frame sharpness and color looks really good on Astrobin examples.

The eternal circle of confusion when it comes to making a decision on astrophotography equipment

And in a complete about face I ordered a checked and tuned GT71. Kinda on the limit of the Fornax with this scope but I have a counterbalance arm so should be OK as long as it's not windy