I have found a discrepancy in the documentation regarding the backfocus distance for the STXL cameras. According to the original STXL camera manual, the optical backfocus distance for the camera plus FW8G-STXL filter wheel is 2.357", but according to the backfocus calculator spreadsheet on the Diffraction Ltd website, this distance is 2.347". Can you confirm which is correct?
Your focuser should be able to accommodate the 1/100 of an inch discrepancy. So I wouldn't worry about it.
In practice there is some variation in the thermal interfaces for the sensor, resulting in some variability from unit to unit. Most of the spreadsheet values were measured from sample cameras. That probably explains the small discrepancy. I agree with Colin, it is nothing to be concerned about.
Thanks Colin & Doug. I was thinking more in terms if I ever have to get another custom adapter made for my STXL camera. Which back focus value should I use to calculate how long my adapter needs to be? Mike
