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SW Evostar 80ED + OVL Off Axis Guider - Spacing issues!


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I'm sure this is just one of many hundreds of posts about correct spacings on here - I think I've just about got it but I need to confirm a couple of things with folks who have more experience than me on these matters.

My scope is a Skywatcher Evostar 80ED-DS Pro - one which I'm sure anyone here is familiar with and needs little introduction. I'm using the accompanying field flattener/reducer, which requires 55mm of back focus.

The off axis guider I plan to use is an OVL Off Axis Guider - it is thin enough that in combination with my camera I should have the required back focus provided the connecting T-adapter is thin enough.

My camera is a Canon 550D (mod), which as far as I'm aware will occupy 46.5mm of back focus.

My question is, what would be the best way to connect the Canon to the OAG? Puzzlingly it seems the OAG has a 42mm screw-ring on the camera side, which I don't have an adapter for. Do these exist? Are there any thin models available such that I meet my back focus requirement?

If there are any other issues with what I'm suggesting please let me know. It's always easier to nail it first time than faff around with ordering adapters only to discover they're the wrong size.

Cheers.

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