Eyepieces 101

by Arden Strycker

With respect to eyepieces, I go by the philosphy if you don't know what you want, you don't really need it (yet). Two good eyepieces will generally be good for most things. You can get additional eyepieces that are really good for certain things. But viewing interest and budget dictate choices.
Here is one of the best sources I found for introducing you to eyepiece choices and what works best for you.
This site is the best I found for rating a particular eyepieces you are considering.
I have had very good success getting specific eyepieces I wanted on the used market (classifieds). No guarantees, of course, but prices definitely better than buying new.
My eyepiece collection, obtained over multiple years?
After spending some viewing time, I discovered I like looking at double stars the most, followed by planets at key times, followed by deep-sky objects when skies are dark (especially at dark sites). For the latter, I have been many times disappointed under less than ideal conditions.
So, my eyepiece choices need to span the full range of magnification and need to be best at capturing contrast and sharpness. Wide views, ultra-coatings, and high costs are not what I focus on, but these are the criteria if deep-sky objects are your main targets most of the time. I did not come by this overnight. I have also added some filters to my collection along these same guidelines. It took some viewing time before my choices became more clear. Some have suggested that if you go to "star-parties" you can ask others to let you try their eyepieces in your scope to see how they perform before you spend your money. This is an excellent suggestion. Don't be afraid to ask!
My list:
Omcon Erfle 35mm. Used for wide field of view, larger open clusters, awesome expansive feel of the universe. I just got this lens and I love it. It cost me $45. TeleVue Nagles are $250+ for similar views. Erfle's like these aren't made anymore because they typically suffer from distortions in the peripheral part of the view. But the Omcon had good ratings and I was willing to live with the limitations for the substantially lower cost. I recently modified my focuser to allow me to use 2" lenses. This is my only 2" in my collection, but the larger size enhances the large field of view. I bought it on the used market.
Meade Plossl 32mm. Used mainly for finding things, but also useful for very large objects. I do a lot of star-hopping, so I use this lens every night I'm out. While a must-have for me, this lens wouldn't be as critical for go-to scope setups. Also, it isn't that useful for final viewing of a majority of the objects I look at.
Orion Plossl 25mm. Used for larger objects and my first lens that came with the scope. I don't use it that much anymore, since getting additional lenses. However it still is the best choice for some of the larger objects.
Meade Plossl 15mm. My deep-sky lens most of the time. Great coating, mid-range magnification, excellent lens (not horrendously expensive, either).
Orion Lanthanum 9.5mm. I use this lens for higher magnification when sharing views with other people, because the Lanthanum series has such great eye-relief. If you must wear glasses, this series eyepiece would be your best choice over Plossls in all range of magnifications. For personal viewing, I rarely use this lens because Orthoscopics give better contrast. The trade-off is that Orthoscopics are also more difficult to use--narrow eye-relief at higher magnifications.
University Optics Ortho 9mm. Best for wider double stars and lower-magnification on planets. I occasionally use this also for globular clusters, which also need sharp contrasty views, but usually I use higher magnifications on them. Great lens. For those who like to study features of the moon, this lens is an excellent choice.
University Optics Ortho 5mm. Used for double stars and planet viewing. I use this lens more than any of the others. Great lens. Great contrast allowing me to see details on Mars and Jupiter, and splitting tight doubles. This is usually the limit of magnification for my scope except when the atmosphere is very stable.
University Optics Ortho 4mm. Used for very tight double stars and planet viewing. However, this lens is only useful when the atmosphere is very stable, which doesn't happen very often. I don't use this lens very often, but when I do, I get the best detail with it. It is also hard to use because of the very short eye-relief. This one requires a lot of patience.
Orion Shorty 2x Barlow. This lens is used to double the magnification of any other lens. It's a great first lens to have because you can have 2 or 3 good lenses and this Barlow doubles your choices.  So for example, if you have a 25mm and a 9mm, this Barlow allows you also to see at 12.5mm and 4.5mm. For quite awhile that's all I had and I still had a lot of choices to cover the full range of magnification. I didn't really need all of the above lenses that I have now. Of course, what I have now gives me better views, but at more cost obviously.
I also sometimes use the UO Ortho 5mm with the 2x Barlow to get to 2.5mm, a very high magnification that is not practical for my scope. But I use this to tweak my collimation on a relatively bright star. Doing so is only useful on very stable nights. Most nights the atmosphere isn't stable enough and doing this tweaking is a waste of time. Even so, you can see what the atmosphere (and your scope) is doing on any particular night.
Plossls have become popular choices for general use, because they render many different types of objects well. Furthermore, TeleVue Plossl eyepieces have become the standard against which others are compared because they are so good. However, for the way I use my scope most of the time, I haven't felt the need to upgrade my Plossl eyepieces.

A couple of weeks ago I tried a 20mm TeleVue Nagler Type 5 eyepiece. It was awesome beyond amazing. Ok. So maybe sometime soon I will break the bank, live with the extra weight, and go for it. "It only hurts once." It really was fun to use on deep sky objects with my scope.
Choices of eyepieces does matter. However, until you know what you want, having 2 or 3 decent selective eyepieces will do just fine.