Re: Optimizing Quad TCC Backfocus Spacing


I just received my TCC Quad. What a magnificent piece of glass! Kudos to the Master optician. 

What is the minimum distance from the back flange of the TCC to a 54mm male reducer that will not cause vignetting for a full frame sensor, assuming no other restrictions?

54mm is the female thread on the front of the QHY medium off axis guider (and filter wheel) which is attached to my QHY 2 inch filter wheel. I'm having a 22.1mm length adapter spacer fabricated by Precise Parts that goes from the 3.27" on the TCC Quad  flange to M54 male to screw into the off axis guider. I've started to worry about vignetting as an after thought. It's on an upgraded  AP130GT f6.3 Star Fire with 3.5" focuser. I have the QHY 54mm adapter kit that will allow shimming to the exact backspacing needed. I've already calculated with my QHY268C that I have about 5mm to play with for adding additional spacers to the 22.1 mm adapter/spacer. While vignetting may not occur on the APS-C sensor, I'll be getting a full frame camera soon.

John J.

If there are any stock combination adapter/reducers made by AP or otherwise that goes to M54 from 3.27", please let me know. I have not found anything in my searching of all vendors except the Badder adapter that goes from 3.27" to M68.

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