Focus on 10 inch dob

[PETER_TRA]

I have a 10 inch dob from bintel with 15mm and 9mm Fully Multi-coated Plossl Eyepieces (1.25") and 26mm Wide View Eyepiece (2"). The 2" has got good focus but the 15mm and 9mm are hard to focus. If I am looking at Saturn it seems to be in ok focus if it’s in the edge of view but if its in the centre it looks fuzzy. Is it just the atmosphere or do I need to adjust something on the scope to make the image sharper?

[mplanet62]

Having fun with wonderful hobby of Astronomy for a while, I bought two different reflector telescopes from two different reputable sellers. None of them was collimated. Most likely, yours is not collimated as well. One of them was well collimated at Bintel (not advertisement) and tweaked later by myself, needed no assistance collimating second one.:)

[PETER_TRA]

i have had the scope since 2009 so i suppose it needs to be collimated once a year? and what is the process?

[mplanet62]

There's plenty advice on the net. I prefer this one http://www.astro-baby.com/collimation/astro%20babys%20collimation%20guide .htm

[barx1963]

Hi Peter.
You should check the collimation each time the scope is moved. Ususally will only need tweaking, but if it is the Bintel brand, the springs on them are not really very strong, so it can easily move.
You should remember taht the higher power EPs are intrinsically harder to focus and need better conditions, especially with bright targets like planets, to give the best views. I have a 10mm Ethos, which is a beautiful EP, but only rarely can I get pinsharp focus with it.

Malcolm

[2stroke]

Lol on a 10" every time you move the thing, haha its no wonder your view is bad. If your lazy get a laser collimator, these things are quick but don't offer the best collimation. For quick ruff as guts visaul there fine but if you wanna see the best results read this http://web.telia.com/~u41105032/kolli/kolli.html also google newton collimation :thumbsup:

[barx1963]

I should be clearer, obviously only check it when you move it before a session! It may seem like overkill but it is a good habit to get into and will alert you to any problems.
Use a laser collimator with care. They cannot fix poor collimation, you need to use a sight tube/cheshire or similar before doiung a final check with your laser.

[jjjnettie]

I check the collimation of my dob before each use. I always seem to have to give the secondary a tweak.
But it only takes a a couple of minutes at the most, and it becomes part of your set up routine.