Does anyone happen to know what the distance is between surface of the CCD in an STX-16803 and the back of the FW7 filter?
This handy Backfocus Calculator spreadsheet will let you calculate that sort of info: https://diffractionlimited.com/downloads/BackfocusCalculator.xlsx
Hello all, I am trying to use the calculator and lost with some of the terminology on it. For starters, I recently bought a used SBIG STX-16803. That also came with (if my memory serves me right - an 8-position square FW) which is self-guided. Can someone confirm if it is the FW8G-STXL? I assume it is. I am also using 3mm thick AD filters. Per the spreadsheet, I am getting backfocus = 70.8mm. Please let me know if that sounds right? Thanks, Dhaval
Dhaval, the FW7-STX and STX Guider are the correct parts for use with an STX-16803. The FW8G-STXL will only fit an STXL camera. What are the serial numbers/model numbers on the stickers on these parts? Then I can confirm what you have.
Hello Colin, Thanks for the response. Unfortunately, I don't have the FW and camera with me right now, they're both at my remote observatory. I do have a couple of pictures if that helps. Please let me know if this helps. Thanks, Dhaval
Ok, that's an STX-16803 and FW7-STX filter wheel. I can't tell if you have an STX-Guider in front of the filter wheel from that angle in the 1904-1 photo. The backfocus calculation would be: Camera 35.3 + FW7 32.9 - (1/3 x 3mm filter) = 67.1mm Plus any adapters.
Ok, the STX Guider is 1.1 inch (28mm) thick, so you will need to add that to the calculation, a total of 95mm.
