I have a Takahashi TOA-150B with a TOA 35RD reducer, the backfocus is 62.5mm I would like to get the SBIG STXL 16200 and use the FW8G filter wheel. SBIG lists the backfocus for the STXL 16200 + the FW8G filter wheel as 60.6. With 3mm filters, that becomes 59.6mm I suspect that even a custom adapter to mate the SBIG equipment to the Tak reducer will be more than 2.9mm? Do I have the figures correct here? Is there any solution? I had read on a forum elsewhere that custom faceplates might save a few mm? Thanks for any help.
Yes it may be possible to do a custom adapter. For example, we have camera lens adapters that protrude a little into the front of the filter wheel. Look at the front of the wheel in the photo below - as long as you don't touch the pick-off mirror assembly you can protrude into the wheel a fair distance. The wall thickness is IIRC 3.8 mm. The other alternative is to use the FW8S wheel and add a piggyback guider, such as the remote head + guider kit.