What is best eyepiece?

[franz_sanchez]

I have a short tube telescope that has a 300mm focal length. It's a 60mm refractor telescope which is about as low as you can go with a telescope. The scope came with a 20mm and 6mm eyepiece. I can see at either 15x or 50x. The highest usable would be 120x magnification but realize something closer to 60-70x would seem much more reasonable.

I was wondering for a telescope what size of eyepiece would be the best? I was thinking of 9mm since I could get one cheap or maybe something else. I was trying to figure what would be a good size of eyepiece so they can replace the cheap 1.25 Huygen eyepieces that came with the telescope.

[RickJ]

Without more information on the scope it's hard to say. There are very good APO or ED refractors in this size and f ratio that can take high power very well. There are many simple achromats that can't. I don't know which you have. But since it came with only Huygen eyepieces its reasonable to assume the latter. Makers of the good scopes in this range either don't supply an eyepiece at all or supply one of higher quality.

The nice thing about good eyepieces is they move up with you. You can sell the old ones with the scope and not be sorry for their loss. So I'd buy with an eye to eventually moving up.

Thus I'd look at something of plossl quality or better. A huygen's usually has a field of view of 20 to 25 degrees while all plossls have a usable 50 degree field of view so take in at least 4 times the sky at any given focal length. Even the low rung hourse brand plossls are a very good eyepiece compared to what you have. While there are other designs that offer an even wider field of view when working in a refractor of this f ratio many have rather poor edge of field performance unless you step up to premium eyepieces that likely cost several times the cost of the scope or use them with a barlow. Some users aren't bothered with elongated stars at the edge of the field of view, if that's you then going wider may be good. If you're bothered by distorted stars then maybe not.

So I'd look to good plossls to replace what you now have by getting a 24mm and 6mm plossl and a 2x barlow (3 element) to fill in the middle power and give high power if the scope is up to it. Viewing through a yellow filter will greatly eliminate color fringing and sharpen the image of an achromat when viewing brighter objects. I'd consider adding one for this purpose. Focal lengths are approximate. You want to choose them and the barlow so you don't duplicate powers.

Locate a local astronomy club and bring your scope to a star party. There you can try their eyepieces in your scope and see what works best for you and your bank account before buying anything.

Rick

[franz_sanchez]

Is it much good to get an Achromatic or Meade MA eyepiece. I know on ebay there is a seller that sells MA eyepieces in 9, 17.5, and 25mm. Or is it just better to get a good plossl eyepiece. For what I paid it was $30 for an ok beginners telescope. I could just get a couple MA eyepieces from these ebay seller and it would be less than what I paid for the telescope. I tried both eyepieces with the telescope and went with the 20mm. The 6mm doesn't have as wide of view. Not so hard on eye's with the 20mm eyepiece.

[RickJ]

No eyepiece will help a $30 scope. You might as well stick with what you have and save for a real scope.

Rick

[Siguy]

No eyepiece will help a $30 scope. You might as well stick with what you have and save for a real scope.

Rick

I disagree, I'm pretty sure I've seen the scope he's talking about and it looked usable, granted a better tripod is added. (I'm guessing it's one of those Cstars that I've seen at Ritz Camera.)

But it is still a budget scope, I wouldn't spend too much on eyepieces. Meade Modified Achromat eyepieces are a decent combination, but be warned, the ones manufactured recently have plasticky construction. Still, they're almost as good as Plossls optically.

[RickJ]

I've not seen that one. At Hyde Memorial Observatory where I was supervisor since 1977 I've seen a ton of $30 scopes brought in by kids and adults wanting help getting them to work. Never saw one we could do much with. Imagine today's economy has some bargains that might border on sort of usable. Still when you spend as much for an entire scope as a basic eyepiece costs you can't expect much.

I've not seen a Meade MA of late but for one in a neighbor girl's 70mm Meade refractor of dubious mechanical quality. It only had a 30 degree FOV and was equivalent to a Kellner. Not bad for a f/10 refractor but pretty lousy in an f/5 one due to the fast light cone. Are those you mention different from that one and how do you tell. Some based on the "upside down" Kellner can be quite a good buy even for a f/6 scope though f/5 pushes them some. The one I saw wasn't that type however. It was just the basic old fashioned version.

F/5 acromats are usually pretty "colorful" so not sure how much a better eyepiece can help them. I'd not want anything of much power. 20x may be all it can take.

The galileo scope the IYA is selling for $15 may be a better deal and you learn something about optics at the same time. With a much longer focal length it will not have the color problems and should work to 50x I'd think.

Rick

[franz_sanchez]

The scope i'm using is good for $30. I don't know what else could be good in the same price range. It's 60mm with a 300mm focal length which isn't very big. The tripod mount is made of metal and most of the parts are actually metal. the lenses are coated and its not that high of quality but at least its not plastic.

The 20mm eyepiece at 15X it works fine. For an easy object like the moon you can see detail. With the 6mm at 50x the view is too narrow and its just better to use the 20mm eyepiece. I have tried Venus and other brighter stars which just come up as clear objects but not lots of detail since this is a small scope.

I would get a better eyepiece such as a cheap MA 9MM or 17.5. I wouldn't think about going beyond 6mm or 50X since this is a small scope. This scope is nice because it can also accept the 1.25 which most scopes for $30 cannot.