ASI533MC use as 2" or 1.25"

kb3puw

I just got an ASI533MC and am learning to use it. My scope (SV48p) can take 2" but so far I have been using the 1.25" adapter. I am not sure but I think the 1.25" adapter is causing vignetting. Is this a common problem down sizing to 1.25? Is it always better to use 2" if possible? I may need to buy alternate filters etc., if that is the case.

w7ay

kb3puw I am not sure but I think the 1.25" adapter is causing vignetting.

The clear aperture of a typical 1.25" filter is 25.5mm.

The diagonal of an ASI533 is 16mm (not the 1" that ZWO claims in their ads).

Don't get fooled by misleading ads. People have kept telling ZWO that the 1" refers to the format of the sensor , not the dimension, but they keep showing a dimension of 1" in their ads.

The format is an old vidicon standard that indicates the size of the tube, not the sensor area. Shady merchants have used it to fool the people who are not aware.

73
Chen

kb3puw

Thanks for the answer. I have been thinking about my setup and suspect that the problem could be due to the 1.25" 70mm extension tube I need to use because the focus tube of the SV48p was not long enough. I am new to everything in Astronomy and am trying to learn to create flats. I think I have recreated the problem but I need to get better at creating the flats to prove it.