Collimation-Again!!

[Paulus17]

Well like most on here i haven't been able to use my Dob a lot yet.

It has only been out once in a car to do some viewing,but wasn't used due to guess what rolling in???

I rechecked the collimation the next day after its ride out the night before and it was fine.

I have used it briefly indoors a few times to view out the window so it as only been dragged a few feet out of where i keep it.

But this morning i thought i would check the collimation again and the secondary mirror was way out.

So i am now wondering how it got like that without it been out the house on a bumpy road.

Have i missed summat out during the collimation.I thought i had tightened all the screws up as per the instructions,and far as i'm aware it hasn't been knocked or anything.

So can anyone tell me why it has moved??

I have re-collimated it again,which i felt more confident in doing and it is spot again.

[Spec-Chum]

Check the tightness of the vane thumb screws. The dust cap on my 200p is quite a snug fit and when on it makes the secondary move every so slightly due to, I assume, very slightly stretching the vanes out. Mine weren't quite tight enough and they never sprung back. A very small tightening of all 4 screws fixed it.

Had me baffled for 2 nights too!

[Paulus17]

Cheers Rich but the vanes are fine,well as far as i know they are??.

I checked those out on my first attempt at collimating,and double checked em today.

[Spec-Chum]

It's Russ lol

The vanes will probably not change in length, I think it's the sides of the tube that (again very slightly) stretch.

Try a little experiment for me...

With the dust cap off, check collimation is dead centre, then put the cap back on whilst still looking into the Cheshire, do you notice a slight movement?

Mine moved a load until I tightened the 4 thumb screws lol

[Starlight 1]

May be the heat of the day making it out ,Best to check them just before dark and Star test later.

Les

[Paulus17]

OOPS.Sorry Russ

Just tried that Russ but there was no movenent,well none that i noticed after trying several times.??

Thanks Starlight.The house is just normal temp with no heating on,though it does get warm in the front rooms ,when the sun is out,but otherwise its just a coolish room??

[knobby]

Have you got kids?

Caught my little one twiddling the spider adjusters, after a little explanation they now know what it does and why not to do it!

Inquisitive little soul

[Paulus17]

Yes i do have kids but they should be old enough now to know better to try and get past this lot

But seriously no.No one has touched it??

[knobby]

Trying laser collimation are we?

Needs to point into the EP holder

[Paulus17]

:grin:

Well i couldn't get to grips with it for collimating so put it to better use