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Zeiss Eyepieces on a Shoestring Budget

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I acquired my first telescope 6 years ago. It was a modest 4.5 inch reflector. As I attended star parties and compared my scope and its views with other scopes, I realized many of the shortcomings of a mass produced scope like this one, including the cheap eyepieces that came with it. A couple of “upgrades” later and my scope was performing much better. Two upgrades were relatively inexpensive; tighten some bolts here and there to reduce backslash and improve the motions and replace the plastic finder with a red dot one. Now I could find stuff. I learned quite a bit from that scope.

The next “upgrade” consisted on getting better eyepieces. Being on a tight budget, I agonized over spending just as much as I paid for the entire scope on just a couple of eyepieces. This hobby is going to get expensive, I thought. To my surprise, a couple of better quality eyepieces made a world of difference. I am not talking about exhuberant eyepieces, just a plossl and an UO ortho. Before, I could see Jupiter as a round circle of light. With these eyepieces I was now seeing cloud bands. The trapezium in Orion was easily split too. These eyepieces were worth their price.

I was struck with aperture fever and I sold that scope in order to purchase a mirror blank and material to make my own telescope. But I kept the good eyepieces. A few months later and my 12 inch reflector saw first light. Perhaps it was beginners luck, but I managed to get a good figure on the mirror. The views were better than I had hoped. I then became sort of an eyepiece junky. Over a period of a couple of years, I acquired several eyepieces that I tried on my scope. I discovered that a fast scope is quite demanding on eyepieces. Having a tight budget doesn’t help either. But with a little patience, and I admit some luck, I have added a couple of eyepieces to my collection, without breaking the bank.

I read a while back that it is possible to use microscope eyepieces on a telescope, as long as one is able to adapt the barrel to the proper size. The standard size for telescope eyepieces are either .965 inches (24.5 mm) or 1.25 inches (31.75 mm). Microscope eyepieces come with 30mm barrels, and older eyepieces came in 23mm. A couple of millimeters doesn’t sound like much, but it is noticeable. Not all eyepieces are worth “converting” over for telescope use. However, I have been quite lucky to find on Internet auctions a couple of Zeiss microscope eyepieces that have worked really well on my telescopes. (I now own 4 telescopes).

The eyepiece on the right is not hard to find, I have seen many like it, but I thought it was out of my range. Yet I got lucky and I got it for under twenty bucks. It has a 30 mm barrel, so I used part from a 35mm film as an outer shell so it fits on my focuser. That is a simple trick that works well. It seems to have some coatings on it. Unfortunately, the weather hasn’t cooperated much so I have not been able to test this eyepiece to its limits.

However, the eyepiece on the left I have had it for a few years now. Again, it was a very lucky find and it is an excellent performer. You may be able to read the inscription on it that it is an orthoscopic eyepiece with a focal length of 9 mm. Great for planetary observing. The second picture shows I have an adapter that goes from 23mm to 30mm for the barrel, and on top of that I use a film canister so it fits smoothly in my focuser. This older eyepiece does not have any coatings that I can tell. Looking through it is as clear as water, very similar to an older RKE.

I while back I was doing some lunar observing. Mainly looking for craterlets on the floor of Plato. I was using a 12.5mm (Edscorp) ortho, this 9 mm Zeiss ortho, and Celestron 7mm ortho. With the 12.5mm It was easy to see the 4 larger craterlets, and a hint of two of the smaller ones. With the 9mm, I counted 7 distinct craterlets besides the 4 larger (easy) ones. When using the 7mm eyepiece I could only discern 3 of of the smaller ones. I have not been able to find and eyepiece that has shown me more, but I add a disclaimer than I don’t have any “premium” eyepieces for a full comparison. Perhaps in the future, I’ll be able to do so.

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