Expert: Paul Wagner - 5/2/2005

Question
Paul,
My wonderful wife got me an 8" Celestron SCT a couple of days ago, and I am having a great time with it so far.  I only have a 12mm eyepiece. I am wondering what other sizes would be good to go with it.  I would like to see the larger planets as distinctly as possible, and I was able to track down M53 last night, but it was pretty small and lacked detail.  I would also like to view the moon (hasn't been up since I got it), but I know the field of view on the 12mm will be too tight.  If can only get 2 - 3 lenses, what would suggest.  Also, what can you about Barlow lenses, do they magnify at the expense of field of view and/or brightness?

Thanks,
Drew

Answer
HI Drew:

First of all, let me congratulate you on choosing a truly remarkable wife!  

The 12mm is a great first eyepiece, and as you have suggested, the next steps are to move on either side of that.  You can get some pretty 25mm eyepieces that should do a great job on the larger field of view objects like Andromeda ( and the full moon--when you are ready to be blinded!)  If you are happy with your 12mm, then stick with the same type for the 25.  A nice orthoscopic at that size is very nice.  Longer than that, you need to get into more expensive and complicate lensw sytems...but I don't think they are worth it for SCTs...

At the other end, try going for something along the lines of a 6-8 mm ortho.  Those are nice, simple eyepieces, great contrast, and if you want more power, yes, I would go with a Barlow.  My experience is that the seeing conditons for that kind of magnification will be rare---and you will usually find that your 7mm ortho shows you as much detail as the same eyepiece with a Barlow under almost all conditions.  The image may be bigger with the Barlow--but it will be blurry enough to cancel out any advantage.

And if there is a local astronomy teacher or club nearby, go to a star party with this scope.  You will learn more in one night like that than you can imagine=-=and you may even meet a couple of guys who let you try their eyepieces out in your scope.

Does that help?  Drop me a note if you need more info.  

And give my regards to your wife!

Paul Wagner