Quote:
Originally Posted by Logieberra
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That would be me
Bit of an update after reading the various questions in this thread.
Is it a pain to collimate?
No, you will get a decent collimation using nothing more than a cheshire collimater, however I would suggest star testing the primary at the start of every session, I'm now working on an advanced colli with mine where I star test and adjust primary, then use cheshire to adjust secondary and then star test primary and adjust again, in other words, not using the cheshire collimater to adjust the primary at all. There is obviously a relationship between the two mirrors (thats how newts work) meaning star testing adjusting primary knocks out secondary a tiny bit, each iteration of the above needs a smaller/finer adjustment until both are spot on. This is a one off, very fine collimation of secondary really and the secondary does hold colli pretty darn well, but still, always a star test on primary at each use.
is the focuser adequate?
Yes and no, if you're considering a scope like this, you should be experienced enough to tweak this area, it has focuser locks each side of the focuser, as pointed out on the video linked above, however, I don't like them, and no matter how I used these two locks, they created image shift when moving focus in and out (obviously not fully tightened but used as tensioners) which in effect also shifts collimation a fair amount in an F4, so I no longer use them. HOWEVER, this is not like the bog standard skywatcher focusers, it's much beefed up, has twice the number of bearings that the tube runs in, and the actual crayfor 'rack' is what looks like a stainless steel screwed on track that actually also runs in bearings, so, each side of the focuser lock on the knobs side of the focuser there are also two tensioning grub screws, taking a little time in adjusting these means focus remains smooth, but stiff enough to easily support my QHY8L and extensions & filter and a baader MPCC with no slippage whatsoever.
Hows the Coma?
Well, with the baader MPCC it's tolerable, just, the plain fact is that at F4 the MPCC is at the very edge of it's tolerance, if you want better, pay a lot more, maybe such as a parracor or one of the 700 uk pounds ASA correctors.
Does it perform?
Ohhhh yes!!!! The beast does take a little taming but to be honest, if you want the results, you have to put the work in, would I buy it again? Now that I feel I've put the time into it, then definitely yes as it's now starting to perform for me.
Finally, the proof is in the pudding, this is 11 frames only, unfortunately we only get about 3 decent hours of imaging time in my part of the UK at this time of year, guided with a piggybacked ST80 and QHY5 using PHD, processed in nebulosity and photoshop. 11 frames, 50 flats, 55 darks, half moon was up and obviously it needs more data, but.... :-
