I recently got a William Optics Redcat 51 petsval lens/scope.
Its a beautifully made instrument and looks fantastic with its red anodising. It matches the annodising on a PME mount.
I was concerned about what its optical performance would be after reading some threads where there were some problems and others where it was good.
I imaged with it using both a Canon EOS R full frame mirrorless and a Sony A7Riii full frame mirrorless.
The usual suspects - Eta Carina, Rho Ophiuchi, NGC6726, Running Chicken, LMC.
It has a very narrow critical focus zone so its fairly easy to tell if its focused or not. Turning the focus ring it clearly goes in and out of focus rapidly.
I am using it manually focused. It comes with a Bahtinov mask but I haven't used that yet.
Stars seem quite good in the corners, perhaps some not perfect but overall quite good. I am also currently using it with a FLI Microline 16. Some images of Vela look fabulous.
I have been using a Pentax 645 F4 EDIF lens and the Redcat 51 is similar but overall better. The Pentax is no slouch so that is statement in itself.
Here is one image from the first set of deep sky images I intend to bore you with!
Mounted piggyback on an AP1600 at my dark site under good seeing and clear skies. NGC6188 was quite high in the sky as well. It was autoguided.
I used an external intervalometer.
https://pbase.com/image/169325482/large
https://pbase.com/image/169325482/original
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