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New scope comments- Skywatcher 8" F4 Quattro
Hi,
just purchased a Skywatcher 8" F4 Quattro CF from Andrews. Also purchased a Skywatcher 4 element F4 coma corrector bought from Astro Pete's. Thought that there may be some interest in my impressions.
This was bought as a portable imaging scope to mount on my AZEQ6.
The scope is nicely finished, baffled, has a 70mm secondary and a focuser that doesn't need replacing with a Moonlight. Had a chance to test it on a trip to Deniliquin.
The result:
The scope is impossible to collimate accurately as it comes from the factory. I have a full set of Catseye tools...
The center spot was 3mm off centre, so I soaked it in a little acetone and, removed it and stuck on a Catseye Hotspot.
The secondary was impossible to set correctly as the adjustment screws are flat on the ends and caused unpredictable movement when adjusting.
The primary springs were so weak that collimation changed markedly after moving 30 degrees!!
I've now rounded off the ends of the secondary screws and replaced the primary springs with much stronger ones. Also got rid of the push screws on the primary cell as the changed collimation when tightened.
The scope now is easy to nail collimation and it is stable when moved.
Optically the scope appears good - not sure how good as seeing has not been good enough to do a decent star test to properly evaluate.
The coma corrector appears excellent. The field of an APSC chip (QHY8) is fully corrected - well there is a little issue in one corner I'm putting sown to lack of proper collimation. Will post some CCD Inspector results later today.
I also bought a second set of rings to make a rotating tube, but these appear to be about 3mm smaller in diameter to the ones that come with the scope. Not sure if the carbon fibre tube is a subtly different diameter to the metal tube? I see a couple of hours work with a belt sander ahead....
Overall very happy with the purchase. I had considered a mak newt, but the lure of F4 imaging in a scope that I could fix if it was a dud and that was lightweight was too much for me....
cheers
Gary
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