As part of a project to explore the capabilities of entry level telescopes that many young people recieve as a gift, nominally 60 and 70mm refractors, I decided to just see what was the availability of eyepieces for them. The scopes come with two or three, which is enough to enjoy astronomy. However, eyepieces are like tools in a tool belt. Each one is used for a little different purpose. Therefore, most people will end up purchasing a few more (in my case many) as time goes on. Most people will end up using anywhere from three to five during a particular viewing session, depending on the rest of the equipment and what is being observed.
Normally, these entry level scopes come set up for one of two possible sizes of eyepieces, 0.965 inch (fits into a 25mm ID focuser), and the current standard 1.25 inch.
With the 1.25 inch telescopes, the eyepieces that come with the scope are generally of reasonable quality. They may, however, be modifications of older designs to keep the initial cost of the telescope down. By using this size, just about any of the modern eyepiece designs can be had to provide eyepiece performance good enough to push these entry level telescopes to the absolute limits of their capacity. For most of the modern eyepieces, it would be questionable to make such a purchase. The point is, it can be done. A second point is, any eyepieces purchased plus the ones the small scope came with can be used on just about any telescope of greater size, quality, etc.
For introductory telescopes using the 0.965 inch format, the eyepiece selection is very limited. A common design for eyepieces found in this size are Huygens. This is the first multi-element eyepiece design and can be considered the beginning of eyepieces in general. This design was a great breakthrough for astronomy three and a half centuries ago. You will normally see an H in front of the focal length number for Huygens. A modified version is called Ramsden. These will be seen normally with an R or an SR in front of the focal length number.
Eyepieces with an F in front are better with three elements. I suspect these are a modified form of Kelner. These should be good for entry level scopes as will Modified Acromats (MA) and a few others. This is about the limit of eyepieces that might be found with the 0.965 format telescope as purchased. These were the cutting edge for general viewing until the the fairly recent development of development of plossls.
With a little searching, I did find that Antares produces a line of Super Plossls for the 0.965 telescope. They are actually 1.25 inch eyepieces that have been fitted with 0.965 barrels. If someone would like better eyepieces for the small format, they can probably be ordered through any company that carries antares products. Antares lists seven distributors, I think, in the United States and 23 in Canada. (It is a Canadian company) I looked on the website of each of the listed US distributors and found only one that listed the eyepies and the price.
I sent an email to Hands On Optics asking if they actually stocked these eyepieces and if they were any good. Sherry Hand promptly replied that the did stock these eyepiece on their site, the price was $20 each, and the reports she was recieving from purchasers were positive. Anyone that might be interested in these can go to
www.handsonoptics.com get into the section of Antares products and look on the last two pages. six and seven, if I remember correctly. This is the limit of what I found of eyepieces in the 0.965 size.
The point of all this is to advise you to purchase a telescope that uses 1.25 inch eyepieces if at all possible. You can use any eyepieces you purchase with telescopes further down the line. Any 0.965 eyepieces you purchase cannot be used later unless you make some kind of special adaptor for them.
Hope this helps and does not confuse or discourage anyone. The real point is to enjoy and learn about the sky. The particular equipment is just details. The fun stuff is yet to come in this series.
Bill Steen
