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Old 17-06-2014, 09:02 AM
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astro744 is offline
Join Date: Apr 2007
Posts: 1,046
Originally Posted by 209herschel View Post
I want to thank everyone for the advice. It looks like I'll be going with the 8.8mm ES and I'll then get a barlow down the track for perfect conditions when I'm out. I'm very happy to say that last night was a big improvement. I was out till late and started looking for Saturn when I was again disappointed by the small image with no definition. Then I decided to just look in the area with the finder scope and investigate anything a little bright. And suddenly I saw Saturn! In the 25mm, it was a small disc with clear separation of the band around it. Moving up to the 15mm and finally the 9mm, I got an excellent clear look. I couldn't see any separation in the rings though. Could this be down to the conditions or perhaps a 6mm would give me the extra magnification to bring more out? The moon was incredible last night also. I think that's excellent advice in the DSOs - at one point I looked with the naked eye and saw a couple of stars, used the finderscope and then the 25mm and saw a rich band of stars that was completely surprising. Really amazing, even though I'm not sure what I was looking at! Thanks again.
Note the 8.8mm will give similar magnification to your 9mm. If you 2x Barlow either later you effectively get 4.4 or 4.5mm which would be good for only the best of nights. I've not used ES eyepieces and cannot comment on whether they would be better than the GSO Plossl but may I suggest that rather than a Barlow you do get the 6.7mm since it gives you an ideal high power in your telescope for nights of reasonable but not necessarily exceptional seeing.

Magnification at f.l.=1270mm

GSO 9mm = 141x
ES 8.8mm = 144x
2x Barlowed GSO 15mm = 169x
ES 6.7mm = 189x
2x Barlowed GSO 9mm = 282x
2x Barlowed GSO 8.8mm = 288x

I personally find the 150x magnification tantalisingly close to ideal but not quite just there for planets. You will find 170x to 220x your most useful power range. That's not to say 150x is no good and on many nights it will be sharper than the higher powers but you cannot get sharper and larger at the same time even on nights of good seeing although on such nights you will likely see more in the larger image.

My first and most useful high power eyepiece was a Vixen 5mm Ortho and it gave me 170x in my 6" telescope and although I craved for something larger at times I learned how to see small low contrast detail on planets which if you can master and you will with time will give you a skill that forms the basis of the art of observing planets.

Note and this is very important; the ability to see very fine detail on planets is greatly enhanced when the object is being tracked and does not move across the field of view. That's not to say that you wont see detail on a non-tracked telescope but for long duration study of a planets features tracking is highly beneficial. Ultra wide field higher power eyepieces can help with non tracked viewing at some extra expense but the object is still moving and the brain needs lock onto the image and not the edge of field to overcome the motion until again the telescope needs to be nudged to bring the object back. I'm speaking from my personal experience and others may have different opinions on the matter.
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