Quote:
Originally Posted by codemonkey
I bought an older GSO RC8 not all that long ago, assuming it was the same focal length as the current gen ones, but I'm getting some unexpected numbers.
PixInsight's annotation script is reporting a resolution of ~0.73"/px, but according to the various online calculators and formula, I should be at ~0.82"/px.
Doing the math to change the f-ratio to 9, giving me a focal length of 1827mm, gives me bang on the ratio that PixInsight reports.
So now my question is... are these old RC8 tubes actually longer than the new ones? Or is PixInsight reporting an incorrect resolution? Or are the calculators/formula only an approximation?
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I don't believe these calculators like CCDcalc are an 'approximation'. So your suspicions about the different focal length are probably correct!
John
