Quote:
Originally Posted by netwolf
Greg, great review. Could you please provide more details about the Lomo Triplet model. I recently got a WO Megrez EDII 80 triplet, its not the Lomo one. I have not had a chance to test it yet, weather is not co-operating when i have time.
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The Lomo lens itself was probably great. Although I doubt the marketing term of super APO applied. Super APO means 4 colour lines cross meaning at a point 4 colours will be infocus. APO means 3 colours in focus - Roland Christen has written this up at various times and there are symbols they use to depict various colours but from memory it was green, blue and I think red. Often in "APO"s it is only green and red and blue is off - hence the violet halos. With Achromats I believe green is usually in focus (as green is more present in eyesight) and red and blue would be out of focus hence the violet and reddish/yellow fringes.
It was the rotatable focuser which apparently was either mounted onto the tube not in a square fashion or the machining of the rotatable focuser was off so that it was out of square to the tube. I attached a red laser to the eyepiece holder and rotated it. I held a ruler over the dewshield to locate where centre of the lens should be - it was about 15-20mm off which is a huge error. Visually I was seeing seagull type stars off from the centre of the field. This wasn't what I was expecting from a "Super APO" best lens in its class scope.
I was told by another person who had the same scope he had a similar problem.
So it probably was the William Optics tube and focuser at fault.
This same lens is fitted in others tubes like Stellarvue, TMB/APM.
I'd go the APM version if I got another one.
Once I corrected the poor collimation it became very sharp and colour free and that was with the collimation still of by about 5 or 6mm.
So an APM version with a feathertouch would be the go but again it costs more but not that much. The focuser was OK but not great. It slipped under load, was machined slightly too large with poor consequences, only had 2 tightening screws when it needed 3 and the focuser itself would slip when trying to focus and you had a bit of weight in it. A long way from a Tak.
This was about 2 years ago now and I may have simply gotten a bum one. These are made by Pern Long who now sells to anyone not just William Optics.
Greg.