WO GT81 and 0.8FF/FR

[scotty38]

Hi all, I know the answer to my question is probably try it but I thought I'd ask first.

I have a GT81 with Flat6AIII and ZWO294MC and I'm still new to this but the results I've had (to me) are great so far. If I check CCD suitability on Astronomy Tools then my scope/camera combination is clearly "better" without the 6AIII.

If I removed the flattener just how much difference would it make? I realise the FL/FR will change of course but I'm thinking impact on guiding, star shapes, necessity to crop and maybe other things too but what are your thoughts?

[Grant Fribbens]

I have the same setup but have not tried it without a flattener yet but I have got a HoTech SCA Field Flattener to try out that arrived last week. If the 294MC sensor size is small enough to avoid the curvature of the field the you might be fine using the normal focal length of the GT-81. I use a APS-C size sensor and I think I would see curvature without a field flattener hence the HoTech SCA Field Flattener. Just need some clear skies!

[iantaylor2uk]

You would have to crop the image to get rid of the funny shape stars at the edges if you don't use a flattener, if you use an APS-C sized sensor. I use the Hotech SCA flattener on my WO 81GT IV and it works well with my ZWO 071MC Pro camera.

[scotty38]

Thanks both, so cropping most likely as expected and maybe that negates the extra focal length straight away. Any benefit elsewhere, ie guiding otherwise it sounds like I'm as well leaving things as they are 🙂

 

Oh, sensor is 4/3 on the 294 so smaller than APS/C

Edited September 3, 2021 by scotty38

[newbie alert]

I'm thinking the reason for not using the reducer is sampling... I bet that you can't see any difference other than abit more focal length in the actual image and you want to offset that with wonky stars so someone's theoretical figures add up..

Sure it could make a difference if you're making poster sized images but most don't leave the laptop screen