The Zoom Eyepiece

Zoom Eyepiece

The “stock” eyepieces that came with my 8″ 200P Dobsonian were great for me to get started. A new owner should definitely get used to them before considering any “upgrade”.

For me, the stock 25mm produced good results but the 10mm was dim and I was disappointed with the clarity of what I was seeing.

I did consider going down the conventional path of getting a few, mid range or better eyepieces in the 6, 8, 12, 15, 20mm range but in the end I took a totally different path and chose a Zoom eyepiece.

A Zoom eyepiece sounds like the perfect solution: a wide range of focal lengths available in a single ocular, to be changed as simply as twisting the barrel. Zoom eyepieces are of course a compromise. Budget zooms tend to have narrow fields of view at the long-focal-length end, they can be heavy, their many glass elements result in internal reflections and loss of contrast and brightness, and of course they’re more expensive than a single mid-range eyepiece.

“With my 200P I have a 50X to 338X magnification range”

There are a number of advantages for a zoom. There is no need to swap out eyepieces in order to find the ideal focal-length of the object being observed. You will have everything from 24 to 8mm with the twist of a hand. For a non-tracked telescope that convenience and speed is a useful feature. At the short-focal-length end, they actually tend to have longer eye relief and wider fields of view than Plossls, Kellners, and Orthoscopics. With the addition of a low power, wide-angle eyepiece and a Barlow having just three oculars can be very convenient. With the 200P I have a 50X to 338X magnification range!

With all optics, you get what you pay for. If you buy a very cheap zoom eyepiece, don’t expect it to perform anything like as well as a single eyepiece. I did consider a good budget zoom eyepiece like the Celestron 8-24mm or the Svbony SV 188P. At twice the cost, the Baader Hyperion IV zoom and Barlow combo is not a budget option but considering this is an all in one option you may be saving money in the long run. With bright, sharp, crisp images, a “widefield” AFOV ~70 @ 8mm, 2” mode with camera threads, Barlow friendly, comfortable eye relief with no blackouts or beaning it is considered the best zoom on the market and get superlative reviews.

I cannot praise the Baader Hyperion IV zoom and Barlow combination highly enough. It has made a massive difference to my observing in terms of what I can see and the convenience of my observing. The only other ocular I have is a 2″ Revelation/ GSO 42mm wide (65°) angle. It is ideal for targeting and looking a wide field objects. So with the 2″ supplied adapter fitted, I now no longer use 1.25″ eyepieces.

It may seem strange to spend half a much on an eyepiece as I did on my telescope but I am so glad I did just that.

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