Zoom Eyepieces

[NorthernLight]

Hi everyone,

since I started observing with a dob I noticed how important it is not loose the target as recentering can be aweful. So I was thinking about a zoom eyepiece that allows me to find and centre with low power and observe with changing powers without going away from the eyepiece.
The most recent talk on zooms here is from last year and saw that Baader came up with a new Hyperion Zoom 8-24mm and Orion introduced a new premium zoom 7.5 - 24mm.

My question:

has someone with some experience on a premium eypiece used these and can comment on them? and if so, are zooms an alternative or just showroom toys?
I want one for planets in my 12" F/5 GSO dob (maybe with 2.5xPowermate (all 1.25" barrel)

Cheers

[Waxing_Gibbous]

Hi Max,
I had a Baader Hyperion 8-24 that was very good for all but wide-field views in a 12" Dob. Sorry I sold it really.
In a recent "Sky at Night" review of zooms though, it came third, but not by much, behind the Meade 5000 and the Televue 8-24s. I don't know what they retail for.
Both Zeiss and Nikon make excellent zooms, but at about AU$700-$1000,
I find them a bit OTT.
Hope this helps.
Peter

[casstony]

I have a Vixen 8-24 zoom that is noticably soft at the 8mm setting and I think the Televue is the same as the Vixen eyepiece. I have a Lunt zoom (US$150, 1.25") which seems quite sharp throughout it's range but I haven't critically compared it to fixed focal length eyepieces.

[JethroB76]

The Baader zoom is very well liked on Cloudy Nights - there are some big threads on the EP forum over there. I think there is a new model out now too.

[erick]

Field of view at 24mm is noticeably narrow in the ones I have looked through. AFOV around 40 deg at this fl. The Baader Hyperion Mark III states 50 deg at 24mm. Better, but basically "plossl". But maybe that is not an issue for Planetary observing? Also try to get one that promises to be parfocal through the zoom range.

[PN PM]

I bought the Baader 8-24mm zoom last year for wintertime viewing so I wouldn't have to remove my gloves when it's -20 deg to change lenses. Unfortunately though, because I was used to observing with 72 and 82 degree fov's, I found this lens to be very dark and narrow, and I don't really use it very often. On the plus side, one advantage to it being dim is that it gives very pleasing views of the moon, as it cuts down the light.

[NorthernLight]

From your comments I can see that the trade off with zooms is field width and illumination - both points that are rather negligible when it comes to planetary observating.

The other important question I have is, how does the Hyperion 8-24mm perform in terms of Contrast and Sharpness? I know that camera zoom lenses aren`t as sharp as primes, is that similar with zoom eyepieces?

[casstony]

Even if the performance of the zoom is not quite up to that of good quality discrete eyepieces, the convenience and versatility of the zoom make it worth owning one imho. It could be used to find the highest magnification on a given night or the best exit pupil for a DSO before switching to the appropriate fixed focal length eyepiece, or you might want to carry a portable scope out for quick looks without taking a box full of eyepieces.

[PN PM]

Max,
When I look at, say, Jupiter, through my 11mm 82 degree Nagler and then compare it with the Baader zoomed-in to the same focal length, I notice a substantial difference in contrast which is - once again - a result of the brighter and wider field of view!
For the money, the Baader zoom is a very good eyepiece. I think this is what you really want to know. Perhaps it`s not fair to compare it to a prime lens with 82 degrees.
For your specific problem of keeping the object centred when changing lenses a zoom lens is good idea, but I find that using a wider field prime eyepiece greatly helps with this too, as the object takes longer to drift out of the FOV.:)

[NorthernLight]

gosh, I wish I had the money for both, the Hyperion and the Nagler, right now :)

Thanks for all arguments, it seems to me the Hyperion is a good choice for a zoom EP.

Clear Skies, where ever you are!