zoom lens

[JanetS (Janet)]

I was just wondering what people think of zoom lenses for telescopes. Has anyone tried them. What was your experience with them?

Janet

[CapturingTheNight (Greg)]

Is there a particular lens you are interested in Janet? What is the purpose of the lens/telescope? Do you want to take photos or do you want to look at things visually? From my experience, yes you can get some reasonably good photos with a zoom lens but you need a good tracking mount for the camera to run on to avoid trailing stars. The focal lengths are pretty small though and are only really good for big nebulas and wide field images. If how ever you want to look at objects in a bit more detail (and photograph them) you can get much more bang for your buck so to speak by getting a telescope like a dobsonian. For the cost of a fairly cheap zoom lens with pretty poor optics for astronomy and a zoom range up to say 300mm ($300-$500) you could get an 8inch Dobsonian with a focal length of 1200mm and see so much more detail like the cloud bands on Jupiter and the rings of Saturn where as through a zoom lens the planets would be just bright points of light.

[CapturingTheNight (Greg)]

And in case I miss understood your original post and you meant Zoom Eye pieces and not zoom lenses: I own an 8-24mm baader hyperion zoom EP and love it. Really good for doing public viewings where you can zoom right out for wide field views of things like big nebulas and then zoom straight in to planets when the seeing allows without having to switch out EPs. Really good to show a wideish view of the Moon and then zoom into a particular crater. Never fails to get a gasp. Another advantage of that particular model is it has a thread under the eye cover that with the aid of an adaptor or two it allows you to hook a camera straight to the EP.
Disadvantages- have to slightly refocus when changing focal lengths, and supposedly not quite as sharp as an equivalent brand prime focus EP but I have no primes to test it on.

[JanetS (Janet)]

Sorry, I did actually mean eye pieces. They seem like a good idea to me, instead of buying multiple eye pieces you buy one that covers the range you need. I just wondered if they were any good.

Janet

[barx1963 (Malcolm)]

Janet
As with zoom camera lenses, zoom eyepieces invariably have to make some compromises with quality. Often you will find one focal length will be very good with others exhibiting some deterioation in image quality.
But they can have their uses and reports from some are that they are happy with theirs, so if looking for an alternative to a box of prime eyepieces, they can be a good idea!

Malcolm

[raymo]

If you are looking at moderately priced EPs, you will find the
Seben 8-24mm [about $80 inc postage from Germany] hard to beat.
I've had mine for several years, and use it a lot. you'll find it on ebay.
raymo

[julianh72 (Julian)]

I bought the cheaper 7.5 - 22.5 mm Seben on eBay for about $35, and I find it really handy! Optics are surprisingly good for such a budget price.

I set it for 22.5 mm for "browsing" the sky, and for acquiring targets, and then zoom in as required for viewing the target, once I have found it. For optimal viewing, I will then swap out for a suitable fixed eyepiece, but it's really handy for general casual star-gazing.

[Renato1 (Renato)]

The Seben 8-24mm zoom eyepiece was a really good buy for me when it cost me around $62 including postage, though it now goes for $79. I have seen comments that the Seben 8-24mm is exactly the same as other 8-24mm zoom eyepieces sold under different brand names, but which cost a lot more - but I can't vouch for that.

That said, the field of view gets narrow as you zoom down to 24mm, and I often do wish I was using a standard 20mm or 25mm plossl eyepiece instead (but can't be bothered going to get it). And it's a bigger eyepiece than the individual ones. So I've mainly used it for camping when travelling light with my small telescope.

And in practice, more often than not, you'll find that you tend to use the zoom at mainly at it's highest and lowest powers, though on occasion it's nice to have the intermediate power.

Here is the link to the Seben store, where it is listed, together with the much cheaper 7.5-22.5mm Seben one, and the more expensive Orbinar one.
http://stores.ebay.com.au/Seben-Euro...=p4634.c0.m322

The thing is, as one looks down the list, if it were me - for general usage I'd rather get either high, medium and low power Orbinar Plossls or the 8mm and 20mm Superwide angle Orbinar eyepieces, or combination thereof, with combined cost less than the 8-24mm zoom (but avoid the much cheaper Seben H and Seben SR eyepieces), since the quality will be about around the same as in the zoom, but with wider field of views.
Regards,
Renato