EP quality question.

[flight69er]

Can anyone tell me if these EP's are any good and which is better?

Sky-Watcher 3.6mm MA 1.25" high-power eyepiece

http://www.warehouseexpress.com/buy-meade-plossl-5mm-1-25in-etx-70at/p13539

I'm fairly new to astronomy and don't have too much to spend so either of these would be ideal to go with my stock EP's of 10mm & 25mm.

[michael.h.f.wilkinson]

The modified achromat is a moderately good eyepiece, but I would not easily recommend it at higher powers. It is a modification of the Kelner EP, found in many binoculars. A Plossl eyepiece is clearly a step up. In fact, when I replaced my Plossl 10mm which I used for planetary work with the (better, longer eye-relief) Vixen LVs, I sold it to a colleague of mine, who had an MA 10mm. I first let him try it on his scope, to see whether he saw any improvement. Next day he came into my office and immediately put down the amount I was asking. His words: no contest.

Plossls do come in different qualities, but in general they should beat an MA. Also, keep in mind the maximum useful magnification of your scope. Simple rule of thumb: the focal ratio of your telescope is equal to the focal length in mm of the EP that gives you the optimum magnification. This is the lowest magnification at which a human observer with normal visual acuity should be able to make out all details. The maximum is reached at twice that magnification (half the focal length of the EP). Above this the image becomes noticeably blurred.

So for my 8" F/10 telescope, the optimum is at 10mm (200x), the maximum at 5mm (400x). However in practice I have rarely gone beyond 250-280x. If your scope is F/5 (i.e. the focal length is 5x the diameter of the objective lens or primary mirror), you must halve the focal length.

[flight69er]

Thanks for your help Michael that makes it an easy decision. The plossl it is.

[John]

The plossl in your link is specifically for use in the smaller Meade ETX refractor scopes. Do check that it will come to focus in your scope before you order it - I know the small ETX's have an odd focus range.