[g__day (Matthew)]

I am trying to ensure I have set my WO scopes up with the correct separation from field flattener to imaging chip. My 110FLT was missing a 16mm tube extender to take it to the 55mm seperation from flattener to cimaging chip (now sorted and images look a lot better).

My 132mm scope has coma too - but from the coma charts I have used (refer below) it indicates the camera is too close to the focuser - whilst I suspect its about 30mm too far separated instead!

My original set up has the field flattener run into a ZWO OAG (with a guide camera focuser add on - moving the imaging chip about 50mm from the pick off prism - so I required about 50mm of tube extensions to bring both the imaging chip and guide chip into focus - but this creates my coma. This all connect into a ZWO 7 position filter wheel and then into a 1600MM-c.

I suspect the correct focus separation is 55mm (an almost industry standard). So the offset dimmensions I am work with sum to be 6.5mm for the camera chip to the body + 20mm for the width of the ZWO EFW + 22.5mm for the width of the ZWO OAG means I need to connect the ZWO OAG directly to the ZWO filter wheel which connects directly to the imaging camera and have only a 6mm extension tube (not 50mm) from OAG to field flattener.

Does this sound right? The OTA I bought here a few months ago (very pleased with it) - it came with the old original field flattener if that helps.