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Orion Optics UK Europa 250mm F4.8


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Just a quick question.

I am waiting on my Cheshire collimation tool to arrive, thought I would have a quick look and see how far off the scope is. “Best method to test on a few bright stars”

Now this is my first real look through the scope and the best description would be that the stars in focus seem to be trailing off to the right, like a shuttlecock. Out of focus test showed inner diffraction circle off center edging towards the bottom left.

I have let the mirror cool down for about 2 hrs, still the same.

Question!!... Is this the normal symptoms of a scope in need of collimation?

The scope was purchased second hand.

Acme

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I have an OO 10" F/4.8 which is now in pretty good collimation - the shadow of the secondary is central in the out-of-focus star image, both sides of focus. It's not perfect I'm sure but good enough to show nice detail on Mars and the E and F componants of the Trapezium very clearly a couple of nights ago.

I think yours does need some attention but you should be able to sort that out pretty easily with your cheshire.

Nice scopes - I'm very pleased with mine and it's really light and portable for a 10".

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Thanks for the replies.

I was starting to worry..

I will end up with a laser collimation kit at some point but I would like to learn the basics and then move on to the expensive quick fix options.

Acme

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Watch out with a laser. Most of them are not good.Meaning they need collimation themselves.

Start easy but adequate : get a cheshire/sighttube tool

If you still want a laser get a HOWIE GLATTER. Expensive,but one of the few that is adequate and build like a tank.

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To learn the old way is a sound idea, first.

My own feeling is that a laser is quick and not necessarily perfect. But then you just give a final tweak using the star test (round diffraction rings) if necessary. The same applies to any method, though. For perfection, finish with the star test. The great thing about the laser for me is that I can do it on my own. You can't be at both ends of a twenty inch at once! (Or I can't...)

There is also a refinement called Barlowed laser collimation which will come up in Google though in fact I never bother.

Olly

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I have one of these also, different question... has anyone upgraded their mirror cell, using the OO 9-point unit?

Mines got the simple 3-point cell. Seems to do the job well enough although I'd prefer a bit more ventilation around the primary mirror - the base plate only has 1 small hole in the centre wheras a lot of the back surface of the mirror seems to be exposed with the 9-point unit - better for cooling I guess.

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I have one of these also, different question... has anyone upgraded their mirror cell, using the OO 9-point unit?

When I spoke to Barry at OO he said the benefit of the 9 point cell really comes in with the better optics (1/8 and 1/10PV) and the bigger apertures. I wouldn't bother with say a 10" with a standard 1/4PV mirror, but with 1/6PV it would help a bit.

Have a word with Barry and he will be able to advise you properly.

John

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