OVL field flattener and back focus for zwo

[smashing]

Hello all,

Just waiting for delivery of a new toy and wondering if I've actually got the right connections for the job (should have checked but it was all on back order and then it all dropped back into stock again so it's arriving a little earlier than planned...not complaining though)

Currently have the OVL field flattener with T ring adapter into a cannon 600d.

This will soon (hopefully) be replaced with a 2600MC Pro and I've been trying to get my head around the back focus situation and have come up short if I'm honest. 

The flattener comes with a T-ring adaptor...I guess I need to measure that and work out the 55mm spacing requirements of this adaptor plus whatever the camera comes with and make up the difference in some way...I could remove that adapter but no one seems to know what the thread size is (I've asked FLO so hopefully some help may be available).

Any pointers would be great and at least it's not supposed to be clear for a while

Cheers

Adam

[adyj1]

I have the ASI533MC-Pro, and there is everything in the box to provide 55mm back-focus to an m48 male fitting (which is what my skywatcher coma Corrector has ✅)

However my Altair Astro Lightwave flattener has a T2 male thread 😔 (with the same 55mm backfocus requirement) which meant that I had to find some way of replacing  the 16.5mm T2-m48 adapter with something that did T2-T2. 

I had no joy finding 16.5, or even 16mm (I could have made up 0.5mm with ZWO-supplied spacer rings). I could have bought two packs of extension rings to provide 2 x 8mm T2 extensions but that was getting costly/wasteful. 

I ended up buying a Baader Varilock 46 to replace both the 16.5mm and 21mm ZWO extension tubes, with the advantage that it lets me fine-tune the spacing if needed. This only arrived yesterday so there hasn't been the chance to try it in anger, but I have successfully done a dry fit. 

HTH

Ady

Edited August 4, 2021 by adyj1

[adyj1]

Just to add, the ZWO camera with an 11mm F-f T2 adapter which screws onto the camera T2 male thread, a 21mmm M-F T2 extender, and a 16.5mm M-F T2-M48 extender. There is a 6.5mm gap between the sensor and the front edge of the camera. 

[AstroNebulee]

I had a similar thought about this and contacted flo as I was thinking of getting a zwo asi183mc Pro for my 72ed and using my ovl FF. They said the camera should screw straight into the FF and then insert it all into the focus tube. This is for my 72ed but not sure what your scope is. 

Edited August 5, 2021 by AstroNebulee