Quote:
Originally Posted by mental4astro
Congrats on the new scope. Your excitement is only JUST noticeable,  ,  .
Collimation thingy: yes.
It will optimise the alignment of the optics and give the best possible image quality.
Barlow lens:  , yes.
I normally don't advacate the use of barlow lenses. They make things more fiddlie, put more glass in the way, and another thing to drop in the dark.
However, in this case, I think a barlow lens would be OK. Your scope being 8" has a max practical magnification of 400X ( rule being 50X per inch of diameter). This also happens to be as high as the atmosphere will allow and then only rarely. I've only had good enough conditions for 360X for an extended time only twice this year, and using my 17.5" dob. 150X is more the norm for max power.
A barlow lens would be the cheapest and quickest way to achieve your highest power. No use going higher, the scope's optics and the atmosphere won't allow good image quality to be visible. You will achieve this 400X by using your 6mm EP with the barlow.
Andrews Com has a decent barlow for $29 plus postage. Most barlows out there would be the same one rebadged.
Learn to use the eyepieces you have first. Each offers different visual characteristics, not just differing magnification. You can use them for wide sweeping views (long focal length), decrease sky glow to bring up details in DSO's (mid focal), and discriminate details with certain DSO's like globular clusters (short focal).
If money is not a problem, you have many, many options. If it is a factor, or just stepping out, I would suggest one other eyepiece: GSO Superview 30mm at $69. Excellent EP for the price. If you can lay out some more: TMB Paragon 30mm, around $300. I have the former (love it) and will get the TMB after I remodel my dob this Christmas (love it more).
Jupiter can be very glarely, making details difficult to see. A little trick here is to make a cardboard mask to fit over the scope effectively to make the apeture smaller! This is one instance when bigger aint better because the focal ratio of diameter to focal length is small. Make the mask to a diameter of about 7" diameter opening should make a real difference.
Mental. |
Hey Mental (Alexander),
Thank you so much for your advice, very helpful. I will be sure to ring Andrews tomorrow to order a collimating tool and I'm just tossing up between purchasing a barlow or 30mm Superview first
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As the weather is pretty crappy at the moment so good time for me to make that cardboard mask. Thank you so much for your valuable time and advice, I'm so excited, I can't wait to get out there again.
Last night was just awesome and I can't wait to get to the country with the family, our son is dying to have a look we told him school holidays, they can all have a look, so we are all counting down the days until christmas holidays then off to the country..we even keep the box for transportation
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Thank you once again and a very Merry Christmas and prosperous NEW YEAR...I'll keep you posted and good luck with your mod's to your scope...and I didn't realise you could get dob's that big...its absolutely mind blowing to me....As you can see I am very new to this
