Zoom eye pieces

[Okeydokey]

Does anyone have a view on these    I gather they may be most effective at the higher magnification, and pretty poor at low magnification?

[Schorhr]

I have the TS 7-21mm and I did read a lot the Seben/Orbinar (or similar Re brands) 8-24mm are a tad better.

21mm is so narrow (40 degree aparent field of view) that they won't show much more then 7mm (60 degree). At 50-60€ for the eyepieces, it makes much more sense to buy a 20 and 6mm UWA for 30€ each, as they give a stunning wide angle view of 66 degree afov, and perform similar on faster telescopes. Okey at f/6 and tolerable on f/5 if you can live with the outer field not being sharp, but it's the same with other Erfle and Plössl.... And the cheap zooms.

The tmb/hr planetary cost 45€ each and perform better on f/5, are still nice to view through (good eye relief and 58 degree wide angle).

Another solution is the Astrozoom, that changes the distance to the barlow element of eyepieces like the great tmb/hr planetary, and a 8mm hr-p will turn into a 7-3mm zoom (or something around that) without loosing afov.

On higher budget there are better zooms, but really, they cost quite a lot. Though something like a Nagler zoom for 3-6mm would be amazing, as you can allways get the most out of the current seeing conditions.

I hardly use my TS and Astrozoom, it's usualy okey to use three, four fixed focal length eyepieces. Even though the zooms will give you a lot to discover and play around with, figuring out what exit pupils/zoom levels work best, the wide angle views are way too stunning to switch to a 40 degree afov again.

[TwoPi]

I've read great things about the TV Nagler 3-6mm zoom (e.g. see this thread), mind you that shouldn't be surprising given the cost.

Still seriously considering getting one though!

[Laurie61]

Does anyone have a view on these    I gather they may be most effective at the higher magnification, and pretty poor at low magnification?

The low mag problem is the relatively small field of view rather than how sharp they are, if you are used to using plossl eyepieces this may not worry you.   With these type of eyepieces the term 'you get what you pay for ' is probably true. The one zoom eyepiece everybody had time for a while back was the previous generation Baader Hyperion 8-24 zoom, they were so popular for a time you could not get one, although not cheap. Unfortunately the newer version seems to suffer from build quality problems,  if you could find an old one second hand it would be worth a look.   

http://stargazerslounge.com/topic/58790-baader-hyperion-8-24mm-clickstop-zoom/

[CodnorPaul]

I have the Baader one (Mark III - not sure if that is the one that is meant to have quality issues as I think it is latest still) - it is fantastic, not had any problems with mine, the views are fantastic, and it saves constantly swapping EPs.  Yes the FOV is narrower at lower mags but for that I prefer a 2" anyway so that doesn't bother me, but for zooming in on planets etc it is fantastic as it lets you find the sweet spot easily

[Stargazer_00]

You can get amazing zooms, it depends on what you're willing to pay - like most thing.

Leica do a 60 degree zoom (constant across the range) and it's 8mm-21mm I think.  I can't recall if it is parfocal across that range, if it was I'd seriously consider getting one.   They are just shy of £800ish I think.

The nagler 3-6 zoom is truly amazing.  On paper it seems like a short focal length plossl zoom showing 50 degrees AFOV across 3, 4, 5 & 6mm and everything in between.  Doesn't sound to specatular until you actually play with it.  The parfocallity means you only focus once and then can wind the magnification up and down without having to refocus (like you would have ifit wasn't parfocal across the range).   There really is no easy way to put into words just how fun it is being able to turn the collar of the eyepiece and see your targets blossom in size but remain in pin sharp focus.    I was looking at the moon just last night at the lowest setting and if you slowly turn up the magnification you get a sense as if you're coming in to land on it!  None of my other eyepieces give this unique experience.  Like I said, if the Leica zoom did this as well I'd probably get one, I just don't know anyone who has one!

[Stargazer_00]

this one is reported (on APM's website) as beating the Leica zoom for telescopic use

http://www.apm-telescopes.de/en/Eyepieces/Zoom-Eyepieces/Meopta-Zoom-Eyepiece-79-mm-158-mm-66-constant-Field-of-View-1.25-Thread.html

It looks like the Leica one I'd hinted at above is actually 60 degree to 80 degree zoom. 

I doubt either are parfocal through their range though and that paired with a constant AFOV, for me, is the key to a zoom eyepiece.

[wxsatuser]

I have the Baader one (Mark III - not sure if that is the one that is meant to have quality issues as I think it is latest still) - it is fantastic, not had any problems with mine, the views are fantastic, and it saves constantly swapping EPs.  Yes the FOV is narrower at lower mags but for that I prefer a 2" anyway so that doesn't bother me, but for zooming in on planets etc it is fantastic as it lets you find the sweet spot easily

I have just got a Baader zoom......cannot compare with anything else but to me it's very good.

Views are excellent, stars nice and crisp.