Colimation Of MAK

[damnut]

Does any one have experience of colimating Konus 150mm mak. The rear cell has three plastic covers housing two stainless, alan keyed (torx) head screws. One of each of the screws is hard in with the second being available for adjustment. My numnut head says dive in and have a go.

However sense kicks in and ask if anyone else has one of these??

Thanks in advance.

[nightfisher]

If its the same as a skywatcher, with a total of six hex heads, 3 small and 3 larger ones then its a push pull set up, i dont remember wich do what so it would be a case of "gently does it", but first ask your self "does it need it"

[damnut]

Hi Jules thanks for the reply. Short answer is yes. Normally would steer well clear, but it has to be done

[John]

I think they are the same, or very similar, as the Altair rumak-cassegrain, iOptron mak-cass and Borsma mak-casses - maybe Altair Astro can give you some advice ?

[damnut]

Thanks for the info John. Its the paired screws I have not seen before. The s\w has 6 individual holes,  3 *2mm and 3*3mm.

I don't want to over-tighten and hear the cracking of glass

[recceranger]

Don't touch it! Send it to a dealer that know what they are doing or you will be chasing error until the first footprint on Mars!

[JamesF]

I can't see how you could damage any glass by turning the screws a little.

If the screws are in pairs I'd guess it's the same sort of collimation arrangement as many newts where the larger screw moves the OTA cell in or out and the smaller is effectively just a locking screw to keep the larger one in tension.

If you have or can make an artificial star and have lots of space then that's probably the easiest way to collimate the scope.  If not then if you have the OTA on a desk or table and arrange to be able to look into the OTA from the front with your eye along the optical axis from, say, a metre and a half to two metres away you can make a reasonable fist of collimation.  Working out what effect each screw has can be tedious, but you need to work things so that when you look down the OTA from such a position you see concentric reflections, not ones that drift off to the edge of the OTA.  On the other hand, if you look down it and see the reflections are all concentric now, don't touch it

I've used the latter method fairly successfully with my 127 Mak after completely disassembling it and needed only the tiniest amount of tweaking afterwards to get it as close as I thought was reasonably possible.

Collimating a Mak is not rocket science and not really that hard.  It can be very time-consuming however and requires patience and being totally methodical.  Were I to do it the same way these days I'd probably set up a video camera in front of the OTA with the display arranged so I could see it from behind the OTA whilst I tweaked the collimation screws rather than having to keep moving to see what effect I was having.

James