Posted 11 July 2004 - 07:49 AM
I find it curious that you list the EP in terms of magnification, rather than FOV. For mags less than 200x, i find I select on the basis of true FOV. I have a 12.5 f/6 and similar EPs and I can offer the following.
As a wide EP, I use a 40 Pentax XL and find it quite wonderful. With a f/6.3, you could use it, or the newer XW and still keep the exit pupil at 6.4 mm. This will give you a TFOV of >1.6°, which is about as wide as you can get with this scope. Myself, I would always want a little more field if I was using the 35 Panoptic. YMMV
I have both the 22 Nagler and the 17 Nagler. I find generally I use the 17 Nagler more often, however I like an EP with a bit more than a 1° field for looking at things like the Leo triplet and other galaxy groups. So I would select the 22 as a first jump from the 40mm. You may find this OK or you may want to consider the 17 - both are superb EPs to my eye.
I tend to make EP jumps in the .5° range, so that would lead me to get the 13 Nagler for .67°. I have never looked through the 12 Nagler, but smaller size would make me go with the 13 (and I have).
The 7 Nagler is a good choice. You should be able to use this level of magnification a lot, on both planets and globular clusters.
Although this depends a lot on your local conditions, on good nights, or if you use fans to cool your mirror, you should be able to go above 300x on planets with some success. A 2.5x Powermate with the 13 Nagler will give you 308x.
Please understand that EP selection and happiness is a very personal thing. We all have different ways of looking at things and determining what we like and dislike about various EPs. You are simply going to have to make some purchases and determine for yourself. Just because people really rave about the 22 Nagler, doesn't mean you should feel compelled to like it. Fortunately Astromart will allow you to find what works best for you.
Good Luck,
Gary Weber
