Telescope Reviews: what lenses would u guys recommend ??

With a 4" telescope, you're going to have to be selective about what DSOs you observe. There is no shortage of interesting sights, to be sure. But you're not going to have the same clarity as you could get through a larger scope. I promise to answer your question at the end of this post. Let's talk first about the specs of your scope - pardon me if this is all old hat to you. It may be useful to recite the three key rules on what you see:

(1) Aperture (unobstructed surface area of the mirror) rules: The clarity of image depends on the amount of light gathered - an 8" mirror of equivalent reflectivity has 4x as much area as a 4" mirror, and a 12" mirror has 9x as much. That is also how much more light they gather. To see what this means at the eyepiece, go here and input your stats (4" scope, 1300mm focal length), and then check what the same object would look like in a 12" scope with a 1500mm focal length.

(2) Aperture also determines magnification limits. A 4" mirror probably cannot deliver much above 200x. Knowing this, it means that eyepieces shorter than 6.6mm will not deliver added detail for you.

(3) Exit Pupils limit magnification. The exit pupil is the diameter of the focused image delivered by an eyepiece. Your pupil cannot expand much beyond 6mm. Wihen an image is smaller than 0.5mm, the light does not hit enough receiving cells on your retina to present much detail. So, as the magnification rises, the size of the image shrinks and therefore a scope can be considered to have a native range of magnification. The size of the exit pupil is the focal length of the eyepiece divided by the F ratio. In your F13 scope, the 32mm plossl yields a 2.5mm exit pupil. Unles you have a 2" focuser, you can't generate a wider one. As we said above, below 6.6mm your mirror won't yield added detail.

Accordingly, your scope is effectively limited to magnifications between 40x and 200x.

So, how many eypieces do you need between 32mm and 6.6mm? Probably an absolute maximum of 6 - 32, 23 (25 is close enough), 16, 11.5, 8, and 6.6; or 3 with a barlow: 32, 25 and 11.5. Since you already have plossls at the longer focal lengths, why not look for something in the 10-13mm range?

I believe in getting good glass first. My .02 is, look for a used Televue Nagler, Pentax XW, Televue Panoptic, Televue Radian, or Meade UWA 5000, between 10 and 13mm. You can get a used Radian for $180, and the most expensive in that list should be a 12mm Type 4 Nagler or Pentax 10mm XW, at around $275.

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Tom
Meade DS-16 (F4.5), C-8, Synta 120mm F8.3 refractor.