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Hi John, The two HEQ5s I have used, would, if well P.A.d, give round
stars at between 120 and 150 secs depending on the dec of the target, at 1000mm focal length. Your 600mm should give around 200 to 240 secs, so your M83 shortened from 270 secs to around 220-240 would
probably have had round stars. It seems that the M83 represents your
mount doing it's thing properly. If only 1 in 4 30sec and 1 in 5 60 sec
subs are good, then something is seriously amiss. It suggests to me that there is play somewhere in the train, and once that play is overcome the mount tracks as it should, which accounts for the fact that the initially
elongated stars don't elongate any further as the exposure wears on.
If the tracking is so bad that 30sec subs are mostly no good, a 270 sec
sub would be horrendous.
raymo
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