[boz_m (Alexander)]

Quite a specific question here. I capitulated and bought an off axis guider (OAG) for my 8” EdgeHD as I had troubles with differential flexure with my guide scope. I am aware however that the EdgeHD has specific backfocus requirements of 105mm when using the 0.7x reducer. I had all the right extension bits to get this but the OAG adds 16mm.

How hard and fast is the 105mm requirement? What effect will I get if I go outside this?

If a problem I will have to look for a spacer that is the correct length which will be tough. Cheers