MN 66 collimation

[godra]

I have one question for owners of maksutov-newton scopes: witch collimation tools you use for collimation of this type of telescope? Witch one is best for this optical system,for you? I use chesire for secondary and laser collmator for collimation of primary mirror and I always think that picture can be better (although is great, compared with many other scopes).

[sixela]

The problem is that the comaless object is determined by the corrector, not the primary, so you can't really expect to treat it like a Newtonian.

Treat it like a Newt and you'll avoid astigmatism (i.e. the entry pupil will be centred with respect to what you use as optical axis.)

Personally I'd collimate it like a Newtonian and then I'd do a star test to null coma, unless you can tweak the mechanics (i.e. ensure one way or another that if you do a Newt collimation, the reflected focuser axis hits the corrector squarely.) It is fairly important to ensure that the offset of the secondary is optimal, both towards the primary and away from the focuser on these scopes, or "Newtonian" tool collimation will say one thing and the star test another and you'll have to settle for a compromise.

Unfortunately, you probably can't use the Schmidt-Newton "blue ghost" trick with a Cheshire (which uses a ghost reflection on the inside of the Schmidt corrector). Well, it's possible you can, so you should at least try it, but my guess is that the shape of the corrector makes the blue ghost unusable.

Just in case:

Complete Collimation of the Meade Schmidt Newtonian - Article

[Whippy]

TBH, it's not that deifferent from uncorrected newtonians but IIRC, the trick with Mak-Newts is to ensure that after basic collimation with your tool of choice (laser, cheshire etc etc), that the diffraction rings are the same both sides of focus. That's what I've done with the MN's I've owned previously and it seemed to work pretty well. There is an article somewhere about Mak-Newt collimation on the net, a bit of a google search should do it.

Tony..

[John]

I've a 6" Intes MN61. A well-collimated laser collimator can be used to get the tilt of the secondary correct but, so far, I've found star testing the best way to adjust the primary. Not that mine has needed much adjustment.

On the MN61 there is an alloy plug about 25mm in diameter in the center of the primary, it's part of the mechanism that holds the primary in place but it means that laser collimators and even conventional cheshires are not useful.

Once found, mak-newts do hold their collimation pretty well.