Anyone familiar with Mak-Cass's?

A very nice gentleman in the UK has offered me a INTES MK67 with 50mm finder, dew-shield and solar-filter for a decent price. Unfortunately in giving the scope a quick once-over he rotated the primary a small but unknown amount. There were no alignment marks on the primary and thus it's not obvious what its initial position was.

My question is this: Is the rotation of the primary in relation to the secondary and corrector critical?

I'm guessing it's probably not given that it's not locked in position. The OTA gets great reviews on Excelsis and other sites, it would be a pity to have to turn it down based on a minor issue.

Martin,

All surfaces in a mak cass are symmetrical, therefore rotation is not important. As long as all else is ok, i wouldn't turn it down based on that. Just a little concern, depending on how the primary is attached to its cell, is there any chance that it might have been glued to the cell and by rotating, it is no longer fixed? I know some manufacturers do this. I suggest you negotiate a buy-inspect-return if not happy arrangement.

Dave.

Fantastic Dave, this is what I expected based on a look at the design.

I'm not sure if the primary was originally glued but one would assume that there would be marks on the glass and cell were that the case. He's very kindly offered to pay for all return shipping costs should the scope not be up to scratch so I'm confident all will be well.

you sure about that Dave?
For SCT's its very important you do not rotate the mirrors.
I would have though that applies to Maks aswell ???

turns out I've a MK67 aswell, its a fine little robust scope.
Its the only scope Ive got where if it fell down the stairs, I'd be quiet confident it would be ok, actually I'd bet it would stay collimated :laugh:

Thanks Dave, didn't consider that; I forgot that in looking at a diagram of the MCT that I was looking at a theoretical telescope with 'perfect' optics.

Part of my problem is I don't really have an appreciation for what I should be seeing other than generic star test descriptions. I was going to build or buy an artificial star which should give me a relatively stable point source to evaluate the optics.

I've searched a number of times to determine if this is an issue and if it can be fixed without sending the scope to the manufacturer but I've yet to find anything conclusive. I was limiting my search to MCTs though so I may have blundered past useful information on cloudynights and other forums.

I've battled with the corrector plate on the SN10 which is an unwieldy bugger, hopefully the lessons learned there will aid me.

well,
From what I've read and seen, the out of focus star images inside and outside the focus point in a MAK are not identical, some of the rings appear brighter inside the focus, this might sound like bad optics but aparently this is normal for these scopes so dont panic.
Also, you might want to look up the collimation procedure for the mk67, its abit more complicated then a sct. It has a large cooling down time, 2-3 hours due to the thick lens so let give ti time before collimating.
Have fun.