2" diagonal and use of 1.25" eyepieces etc

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2" diagonal and use of 1.25" eyepieces etc

#1 Post by cmcdougall » Tue Aug 14, 2012 7:53 am

Hello all

Now I know these might sound rather silly questions to many of you seasoned astronomers but having just acquired a new bigger telescope to replace my SW 127 goto, I am a little unsure.....

I now have a Meade LX200 ACF 10" UHTC Optical Tube (and NEQ7 PRO Mount), which necessitated either a 1.25" plate adaptor or a 2" diagonal......I opted for the latter, since I figured I might, at some stage, use a 2" eyepiece.

Am I right to believe that 2" eyepieces are really only useful at lower magnifications and that at higher magnifications there is really no real difference between 2" and 1.25" items?

Also, I am going to be using my adapted webcam for some astrophotography and was considering purchasing a Televue Powermate, which is supposed to be a very good alternative to a barlow lens, for planetary imaging. My question is, should I buy the 2" version or the 1.25" item (much cheaper, though not cheap!), since planetary stuff is usually done at higher magnification than deep sky imaging and if my above belief is correct, I would see no discernible improvement with the 2" item?

I hope I have made my questions reasonably clear...it is quite difficult to phrase them for one as green as me, but please ask me for clarification on any point if you feel you might be able to give me some assistance.

Thank you in advance,


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Re: 2" diagonal and use of 1.25" eyepieces etc

#2 Post by rwilkinson » Tue Aug 14, 2012 8:47 am

Yes, you made the right choice on the 2" diagonal, since "what will hold a lot will hold a little".
I always use my 2" diagonal with a 1.25" reducer when fitting smaller eyepieces.

It's true that you'd only need a smaller diameter Barlow/Powermate with the tiny webcam sensor, but I suggest waiting before buying any eyepieces until you've tried a few down at Kelling Heath...


Re: 2" diagonal and use of 1.25" eyepieces etc

#3 Post by cmcdougall » Tue Aug 14, 2012 3:38 pm

Thanks for that Ross, that is just the sort of advice I needed. I will use Stelling Heath to try some equipment out.

If in future I was to buy a dedicated astro camera, would the smaller Powermate (1.25") also accommodate it, or do cameras come in different sizes? I am just looking at as much 'future proofing' as is practical/affordable. :)

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