Askar FRA300 vs WO Redcat 51

[falken]

Looking at an wide field imaging scope for my ASI1600 with EFW. I’m debating between Askar FRA300 and WO Redcat 51. Whats your opinion? Thanks.

[Elp]

They're both supposed to be very capable. If you didn't need the EFW I'd recommend a Samyang 135mm F2 lens.

[falken]

Thanks @Elp The Canon version of the Samyang 135mm allow EFW to be used but not in combination with OAG. 
 

135mm is to wide and I hate dealing with backfocus at fast focal ratios.

[Elp]

Tbh, using the zwo EF adaptors (there's a filter drawer one, and a standard one which you can also screw in a 2 inch filter), no real need to mess with backfocus, just use the 11mm female to female m42 coupler ring to camera (6.5mm front to sensor types), unless you like stressing yourself out...

I've been thinking about a redcat, but it won't compete for raw speed. The scopes would likely be better for field flatness if you plan on going full frame in the future. Either will be good, I get excellent results with my Z61, but it's a doublet. The SY has the same 60mm diameter front aperture, but usually has to be stopped down to around F2.8.

Edited September 2, 2023 by Elp

[900SL]

I have had major issues with tilt, decentering and back focus with a Samyang 135. I'm currently bagging hours of data using a RedCat & 533mc combo. Excellent flat field, super little scope, I have an EAF and using an ASIAirpro 

[falken]

11 hours ago, 900SL said:

I have had major issues with tilt, decentering and back focus with a Samyang 135. I'm currently bagging hours of data using a RedCat & 533mc combo. Excellent flat field, super little scope, I have an EAF and using an ASIAirpro 

Yup! Back focus at f2 is a nightmare... I’ll pass on the Samyang.

The main advantage of the Redcat is that it has a helical focuser. Helical focuser eliminates the problem with flex and tilt on the focuser.

Edited September 3, 2023 by falken