A double up like that could mean a bumped mount
Also a 2 min exposure is hard going for a focal length of more than 50 to 100mm on the SA mount unguided
We have only just had a number of successful exposures with a 200 canon at 1.5 mins
Drop your exposure down to 1 min and raise your ISO? Maybe even 30 secs?
It is a good mount but has serious limitations for anything over 100mm f/l
It has a guide port though!
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