Mak-Cass Misbehaviour

[LMC]

Though this is my first Mak (an IM715D), i've read all the "how-tos" and such.

Cooled to ambient, collimated, etc. etc.

Did some cruising and got pinpoint stars then shifted to Saturn - spectacular.

Picked up the scope & mount and moved it about 10 ft to clear the trees and low and behold - I can still focus Saturn (just), but stars will not come into focus no matter what. Collimation seems OK.

Any thoughts?

[GazOC]

What do the unfocused star images look like? Do they have the central obtruction centred or off to one side?

[AndyH]

The Intes Micros have a huge range of focus with the moving mirror. Has the focus knob come loose on the shaft? There should be 1 or more tiny grub screws on the knob.

Cheers,

Andy.

[LMC]

Hey GazOC,

When centred in the EP the CO appears perfectly centred in the ring. If I move the star to the edges of the field it appears slightly squashed on 'top'. I did a star-test earlier and the diffraction ring was round no matter where it was placed.

Hi Andy,

Yes actually. The knob seems a little loose (waggles about 1mm in any direction). Unfortunately I don't have hex key small enough handy to tighten it!

[LMC]

Oh good.

It's clouded over now.

All suggestions gratefully received and will try again tomorrow.

Thanks guys,

Peter

[AndyH]

Let us know if tightening the knob cures it. If not, we'll need to get our thinking caps on:icon_scratch:

Andy.

[LMC]

Ta!

[Ender Of Days]

You'v not knocked the eyepiece have you ?

I once caught mine when moving the scope and pulled it out slightly,

Just thinking out loud,

JJ..