PDA

View Full Version here: : Tell me about your zooms


Miaplacidus
13-02-2007, 07:08 PM
OK, ok. I have an ETX 105 (FL 1470), a 200 mm dob (F6) and a FD 80mm refractor (FL 555, F6.9). I already have some premium eyepieces (LVW and Radian 5 mm; Naglers; Pentax XW 10 mm). But I'm thinking of getting a general purpose, grab-and-go zoom eye piece, somewhere in the 8-20mm range, that would be suitable for all these scopes. I like decent eye relief and hate kidney beaning. I like a wider field of view, but not at the expense of sharpness on axis, and preferably something that doesn't weigh a kilo. I would use it in daytime on the refractor if I could. I don't want to have to remove it to change focus, either, but rather something that moves smoothly.
Time was all zooms were rubbish, but I've heard times have changed. I've heard that Leica and Pentaxes are among the best, but I see that WO have one now, and then there is the generic Televue/Meade/Vixen zoom. (I've already discounted the heavy Speer-Waler.)

So tell me, which one should I buy?

(And don't say "profigliano"!)

Brian.

ausastronomer
14-02-2007, 08:27 AM
How much are you prepared to spend :)

CS-John B

Miaplacidus
14-02-2007, 01:08 PM
Yes, I should have said, shouldn't I? Well, I was sort of leaving that open. Seriously, if someone could persuade me that $700 was actually worth it (the more expensive of the two Pentax?), then I guess I would actually even give that a lot of consideration. (My problem, being in Hobart, is the extreme difficulty of trying before buying.) It isn't that hard to justify a good zoom, I figure, if it can replace two or three other EPs. Otherwise, a sensible restriction would be sub-$500. Really, if you could graph such a thing, I'd be looking for where the value line crosses the quality line.

Just so you know, I'm pretty set at 5 (LVW), 10 (XW). I'm planning to swap my 12mm Nagler for a 17 at some point. And I'm happy enough with my cheaper long FL EPs.

Cheers,

Brian.

Miaplacidus
15-02-2007, 07:43 AM
Is this a silence that speaks volumes? Are zooms still unpopular? Could it be that nobody uses one?

BTW, I am just as interested in any user's negative experiences. Criticism is probably more useful than simple praise.

Cheers,

Brian.

casstony
15-02-2007, 01:30 PM
I've been holding back waiting for a more skilled/critical observer to comment but since none has here's my opinion; the modern zooms are good enough that I wouldn't be without one for the convenience. I've used a william optics/proxima 8-24mm and a vixen 8-24mm and they both looked about as sharp as a plossl to me. The vixen may be a little soft at 8mm. Before accumulating the Nagler, Panoptic and LVW I have now, I used the zoom for most of my observing though now it mainly gets used in my PST.

The new Hyperion zoom is getting good reports and may be worth looking at, though I don't like the look of the eyecup (personal preference - I like a narrow eyecup rather than a wide one).

janoskiss
15-02-2007, 01:47 PM
All the zooms incl the pricey ones go very narrow in the AFOV at the low power end which kind of defeats their purpose for general use. The only use I see for zoom eps is at high powers, for observing planets in a tracking scope, where magnification is important but FOV is not.

astropolak
15-02-2007, 02:00 PM
I have the Vixen 8-24.
Surprisingly good quality optics, good enough to see a lot of detail in planetary observing. Little ghosting, no light scatter.
The FOV is nowhere near good enough for DSO's 50 deg at 8mm focal length, 40 deg at 24 deg.
It is not as enjoyable to use as for example Pentax XF or XW but its light, relatively cheap and it has 20mm eye relief.
I use it as calibration eyepiece in my LX200.
Funny only a year ago or so I thought it was all I'll ever need. This is before I've discovered Pentax eyepieces - with the help of John (Ausastronomer)....mostly.

RGDS Joe

Miaplacidus
15-02-2007, 06:46 PM
Thanks for the tip about the Hyperions, Tony. I will look into that (pun intended). I doubt anything could beat a 10 mm Pentax XW in the PST.

Thanks for reminding me about the narrow FOV, Steve. I hear that the expensive Pentaxes have quite respectable fields (42-60 degrees, supposedly), as too did a Leica I looked through in the daytime once. But most of the 8-20 mm range really isn't "planetary" magnification in my scopes, so the purpose becomes a bit vague, doesn't it?

And thanx, Joe, for reminding me about how good the premium EPs are.

So that's settled then. I'll buy either a Hyperion or a WO or a Vixen zoom just for fun, and get myself a 17mm Nagler and a 7mm XW and an 8mm LV for more serious viewing. Excellent!

Now, who can I kill?

tegea
16-03-2007, 02:26 AM
Hello,

Very interresting subject ! I'm also currently looking for a zoom eyepiece. I would like to have the best possible optical quality and the less "tunnel effect" as possible in wide FOV.

There are quite a lot of 8-24mm zooms (TV, Vixen, Meade...) but those are almost all the same and they are not satisfying. I Tried the TV 8-24 on my tak FS60 and I found that the image sharpness was not very good, and that there was a yellow color in the image.

During my searches on the net, I found that the best zoom eyepiece were not the astronomical ones, but the eyepieces for quality spotting-scopes. People who tried them for astronomy all agree that they are far better than the astronomical classical 8-24mm.
Here you can find :
- the NIKON 7-21mm "SpottingScope" zoom eyepiece (not the "FieldScope" one). FoV is 38-60. You will need to find a 1.25" adaptator to use it. It is described to be the sharpest, and to have the better light transmission abd therefore the best contrast. No image distortion. Tunnel effect exists, but less than in the classical 8-24mm. This one is quite cheap : around $300.
- the LEICA 7.3-22mm zoom. FoV is 38-68. A 1.25" adaptor is available. Sharpness is just a little bit lower than the Nikon. Curiously, it is described as having no noticable "tunnel effect" at 22mm. Around $750.
- the ZEISS 8.4-21.5mm zoom. FoV is the best of all : 49-68, "No tunnel effect" ! It is as sharp as the Nikon but has a small amount of image distortion at 21.5mm. It can be purchased with a Zeiss 1.25" barrel. Around $600.
- There is also a SWAROVSKI zoom eyepiece which should also be a good one, but I found nobody who tried it for astronomy. Around $650.

I will probably purchase the NIKON one as it is excellent optically and quite cheap. My second choice would be the Zeiss because of it's amazing 49-68 FoV.

MikeyB
16-03-2007, 07:36 AM
I've got the Nikon Fieldscope MCII zoom eyepiece, which I believe is 7 - 21mm, although Nippon Kogaku seem to release remarkably few specs for their gear, even top of the range stuff like this. Nikon eyepieces use a non-standard screw mount for which Tomy make an adaptor to 1.25" in their Borg series of astronomical fittings (available through the excellent Hutech: http://sciencecenter.net/hutech/borg/parts/html/7162.htm).

The zoom is primarily used in my PST, where its high contrast and very flexible focal length work brilliantly and the somewhat narrow field of view at lower magnification is not an issue. It is also a splendid planetary/lunar viewing eyepiece - if it wasn't for its dedicated PST usage, it could easily replace my fixed eyepieces for those applications.

In a previous life as an amateur photographer, I always understood that zooms suffered from low contrast and indifferent resolution - seems nobody told the wizards at Nikon!

MortonH
16-03-2007, 12:28 PM
I have a Tele Vue 8-24mm zoom, bought about 6 years ago. on an 80mm or 100mm wide-field refractor they are quite versatile, although I find that at the 10-8mm range the image gets a bit soft. The most annoying thing is that it is not parfocal, but it's nice to adjust the magnification to improve the contrast (as you go to higher mag). The field of view is also very narrow. Doesn't bother me too much for atsronomy unless I want to see large objects, but try it in the day time and you really notice how restricted the view is.

Quality is reasonably good for the price, but if you have premium eyepieces (I have a couple of Radians/Naglers) you will notice the difference.

Morton

tegea
16-03-2007, 07:52 PM
MickeyB > Do you know the difference between the 2 Nikon zooms :
- the spottingscope MC
- the fieldscope MCII
I do not have any technical specs of the second one. The only thing I know is that it is more expensive than the first one.

And thanks for the Hutech link ! It solves the problem.:thumbsup:

MikeyB
16-03-2007, 08:42 PM
I'm glad if I've helped a little, Tegea.

The main difference between the two eyepieces is that the MC has a 2.25x zoom range, while the MCII covers 3x (sorry for such low tech data, but Nikon don't reveal much!)

The other comparative specs are on this page: http://nikon.topica.ne.jp/bi_e/products/nature_a.htm

Miaplacidus
18-03-2007, 12:11 PM
Thanks for your comments everybody. I ended up buying a 8-24mm zoom for $110, figuring I could hardly go wrong and that it would be suitable for star parties. As expected, it suffers like all the rest from a restricted FOV, but it foots the bill for quick looks with the refractor. I'll save my money for some prime non-zoom EPs.

astroturf
19-03-2007, 08:44 PM
Hello everybody

I am/was about to purchase a teleview 8-24 zoom lens
this nikon zoom sounds like it's the business

does anyone know where one could be purchased in sydney or anywhere in australia?
thanks
Bryan

MikeyB
19-03-2007, 09:46 PM
Sirius Optics (http://www.sirius-optics.com.au/nikon%20sscope.htm)

and

NVT (http://www.nvt.com.au/Spotting-Scopes/Nikon-spotting-scopes/Nikon-Field-Scope-Accessories/)

both list the Nikon zooms on their websites, but you could also try BinTel in Sydney (https://www.bintelshop.com.au/welcome.htm), who list the Nikon spotting scopes if not the eyepieces.

There may be others too - spotting scope buyers are a different mob from the astro crowd!

astroturf
20-03-2007, 09:23 PM
Hi guys
this might seem like a dumb question
would an eyepiece like this pentax model
http://televue.telescopes.com/products/pentax-smc-zoom-6-5mm-19-5mm-xf-for-65-scopes-34438.html
be suitable for sky observing, If it would be how would you all rate it?
I'd heard someone mention a pentax zoom earlier & wondered if it was this one
Thanks
Bryan

tegea
21-03-2007, 10:23 PM
I never looked through the Pentax zoom but read that it was sharp on all the FoV at 19.5 but not so sharp at the center at the short focal length. The center "quite" sharp area at the long focal length is approx. 30. The rest of the FoV is less sharp. So this pentax SMC XF zoom might be good but not excellent.

I found the following very interresting test report about zooms here : http://www.birdforum.net/showthread.php?t=73582 It says that the Baader Hyperion zoom eyepiece is a really good one. In Addition, it is quite cheap !