Quote:
Originally Posted by Rerouter
Bilden that is part of what led me down this path, your not the only one that noticed this quirk, however I wanted to go furthur and track down the why
This thread is the main point I found towards how to resolve it, and there are about 18 other threads along similar lines, usually for smaller newtonions, with so many "I fixed it" end points after being told to buy a shim kit, and never describing the added distance 
https://www.cloudynights.com/topic/5...oma-corrector/
I should add, while digging, it seems the paracorr and GSO have different offsets for different situations, the GSO seems to need to change by 1mm per 100mm of focal length delta from 850mm, which I think could probably be mapped back to F/stop, (55mm at F/6), (54mm at F/5) etc, the paracorr seems to have a tolerance about 0.7mm from some threads to completly flatten it.
Due to how small the images are from maxpilote's its not much to show, but without its saying about 12% curvature, with about 26%,
Right now I'm at 54.6mm spacing, based on my F/5 ratio, I expect I will need to add 2.5-3mm to zero out this curvature, which I was hoping to cross reference a little with this thread, the more data points, the higher the confidence I can have, and hopefully help others get better images out of this device (the conic calcs seem that once shimmed is one of the better coma correcters)
Startrek would you happen to know the total distance of your setup, (filter thickness aswell for compensation)?
Jahnpahwa I'll try and get some subs next clear night, (dont have with / without from same night), in return could you try and arrange a similar pair, and how far over 55 you are, the difference between apeture I am not yet clear on. only a clear trend on F ratio. |
Distance from the sensor protection glass of my 2600MC to the ridge or lip of the Baader Mk3 coma corrector or where it stops into the focuser is approx 62mm
My 2” ZWO Duoband filter is screwed into the end of the Baader Mk3 coma corrector.
I use this set up in my 8”f5 newt , 6”f5 Newt and 6”f6 newt and to be honest I can’t notice any discernible curvature across the field , all my images look fairly flat and if there is any curvature it is negligible
Hope the above is of some assistance
Martin