Please recommend eyepieces for my Astroscan

I just recently obtained an Edmund Astroscan with a 28mm RKE eyepiece. I understand that the current new basic Astroscan package includes two Plossl eyepieces, a 28mm and a 15mm.

I'm new to this so am wondering whether this RKE 28mm is as good as the Plossl version and would also like recommendations on other eyepieces to obtain. According to my calculations, the 28mm gets me 16x magnification. And I understand from a review I read that the Astroscan can reasonably handle up to 100x. So should I seek out a 15mm (30x) as per the current packages or go for higher power like say an 8mm (55x) or even a 6mm (73x).

I also need recommendations as to brands/models. I want to buy quality to the level of my Astroscan without going broke. Recommendations as to size, brand/model, and approximate prices would be much appreciated.

Thanks in advance,

Brian

Hi Brian.

I have the complete line of RKE eps as well as the TeleVue (TV) Plossls. Quite frankly, visually they are quite comparable and compete head-to-head in my 10" f/5 scope. The TVs are also about $30 more each than the RKEs. So between those 2 lines, I'd choose the RKEs. The RKEs run about $55 each and give you a 45 deg afov. The TV plossls give a 50 deg afov and run about $85 each. However I find the RKEs are closer to 50 than 45 degrees.

If you wanted to go a step up in performance, apparent field of view (afov) performance, and quality, and price, perhaps the Orion Stratus but they are $119 each with 68 deg afov!! Would be definite keepers if you move up in scopes.

Be warned though that the very fast optics on the Astroscan, and it being a beginner scope, means you will see star images around the outside of the afov that are blurred or streaked in appearance. So don't break the bank on eyepieces unless you plan on getting other scopes.

So basically, at the $50 price point, I'd say the RKEs are fine for you, just supplement your 28mm with the two others you mentioned.

If you want a lot more afov, the Orion Stratus would be great, although a bit large in size for your scope and also a lot more money at $119 each. But good performers.

But since you are just starting, maybe you should just get an economy plossl and get your skills and interest up, then move up to the Stratus. In that case, University Optics makes a 52deg afov plossl for $29. Hard to go wrong for $100 you can get 3 new eps to compliment the 28mm RKE you have on hand.

It's a complicated eyepiece world...but fun

-Bill

Brian:

The AstroScan has a focal ratio of about F4. This means that eyepieces like RKE's, Plossls, orthos etc will show a good deal of astigmatism, ie towards the edge of the field will not be sharp and indeed quite ragged.

The way around this is to use a barlow when ever possible, a 2x barlow makes the Astroscan look like an F8 scope as far as astigmatism is concerned.

Also, the Synta 9mm WF, sold under a variety of names including the Orion Expanse, is a nice eyepiece in a fast Newt, it has a barlow built in. The edge is quite well corrected and it provides a 66 degree AFOV.

The 9mm with the 445mm focal length of the Astroscan provides right at 50x, with the 2x barlow it will be at 100x...

Jon