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Leica Zoom 25x-50x ASPH (17.8-8.9mm)

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#1 mloffland



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Posted 14 January 2010 - 12:07 PM

Leica Zoom 25x-50x ASPH (17.8-8.9mm)

#2 Starman1


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Posted 14 January 2010 - 01:57 PM

Whereas I only had this eyepiece to use for a short while, I also concur that it is sharper and nicer to use than other zooms I have had experience with.
The 2:1 zoom factor says it is unlikely to be one's only eyepiece. But the focal length range does seem to encompass the majority of deep-sky uses in a lot of scopes.
Lunar and planetary observers are unlikely to go for this eyepiece for many reasons, but I feel its best use would be as a deep-sky eyepiece, where wide fields and good contrast are important.
Swarovski has also released a similar zoom. It would be interesting to compare the two.
Zeiss, on the other hand, has gone for magnification range, with a new high-end spotting scope zoom of 3.75:1 If sharp, that could be the one eyepiece many lunar and planetary observers are looking for.

A very thorough and well-written review. Kudos, Andreas!

#3 andydj5xp


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Posted 14 January 2010 - 03:26 PM

Don, thanks for your kind words.

I consider this zoom particularly well suited for lunar observations where the range of magnifications from my experience is fairly small. I'm mostly using it between 140x and 210x (exit pupil 1.0mm to 0.67mm) depending on the seeing conditions.

OTOH using it with 2.5x barlow factor (138x to 275x) I can cover all mags for planetary work.


#4 Tamiji Homma

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Posted 14 January 2010 - 10:45 PM

Hi Andreas,

Finally published :) I enjoyed reading your review. I agree with all your points in the review.

You can replace Radian 18, Denk 14, XW 10, and Nagler 9 with single Leica Zoom, not only covering focal length and AFOV but also possibly optically outperforms some of them. That's powerful eyepiece :)

I often use it with Barlow lens (Baader 1.8x) with f/8, f/7 refractors. It almost replaces my planetary set AII-4,XO5,AII-6,TMB SM-7,AII-10mm on Tak Turret. Leica Zoom has much bigger AFOV and good eye relief as bonus.


#5 ibase



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Posted 15 January 2010 - 09:56 PM

Andreas congratulations on the great zoom review! The Leica ASPH zoom is a dream EP, glad to know through your review of its capabilities and availability - i.e. if I hit the lotto some day. :grin: Thank you and regards!


#6 andydj5xp


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Posted 16 January 2010 - 04:09 AM

Some info about the neccessary 2" adapter for the Leica ASPH Zoom:

I'm using a modified Baader 2"/T2 (#16) adapter. The original adapter is shown here:


The neccessary modifications can fairly easily be done at home requiring only little DIY experience:

1. the T2 male thread on top has to be removed

2. the remaining opening of 37.8mm width has to be widened to be about 40mm

these two tasks I've done with my Dremel multitool

3. about 5mm below the flange of the 2" nosepiece three threaded holes spaced 120° have to be applied. I've chosen M4 (4mm metric), you could try NC/UNC #8 (4.166mm 32 TPI). Three Allen bolt will be used to fix the adapter onto the eyepiece bayonet.

Through the initiative of CNer Tamiji Homma a beautiful 2" adapter has been designed by Starlight Instruments. Just contact


The adapter is shown


Scroll down to post #3368889


#7 bpdinse


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Posted 17 January 2010 - 12:23 AM

Andreas, very nice review. Thank you for taking the time and posting. I've been waiting for this to be posted for a while now and it was very nice to finally get to read it.

It was based on your initial discussion of this zoom months ago that I recently decided to buy one. I also purchased the Starlight Instruments adapter. It is beautiful but also expensive at $350.

I have to say that this is one amazing eyepiece. It is even more amazing for being a zoom. Over the course of several hours one evening, I swapped this zoom between my 17mm Ethos, 10mm Ethos, and 8mm Ethos (I have the 13mm Ethos, but for whatever reason, I just did not compare it - a future comparison). This Leica zoom clearly bested the 17mm Ethos in contrast and sharpness (including center). It was difficult for me to believe and I was only willing to believe it after an hour of back and forth between the two. It was not a very subtle difference so I was paying close attention to seeing condition variation (which shouldn't have been much of a factor at this low mag). At 10mm, both the 10mm Ethos and the Leica seemed about equal - an edge to the Leica... maybe. It was not conclusive because seeing conditions started to degrade the image through both (I was testing in my 20" f/5). Even though they were not at the same focal length, I looked through the Leica at the shortest focal length, and then looked through the 8mm Ethos. I guess 8mm was a cliff for my scope because seeing conditions were not letting me get anything good, while the 8.9mm Leica didn't look much degraded from the 10mm setting.

Now here is an even more amazing thing to me: I can't tell the difference between the Leica at around 16mm and the Zeiss ZAO II 16mm except that the Leica is a wider FOV (and it has that same sharpness and contrast all the way across the FOV). Same thing you found. I would have found it difficult to believe had I not experienced it for myself.

To me, this is not just an amazing zoom, but a wonderful eyepiece that is above some other high-end single focal length pieces. It has the potential to replace 3 of these with no compromise, unless you count ultra wide FOV as a must have. I was not sure that I'd keep this piece, but now I find that I don't want to part with it. For my 20" f/5, it is a hard choice - I will probably still grab for the Ethos as I am often looking for max FOV at a given mag. The Leica will probably find a home in the long focal length refractor that will be coming home in about a month.

I have to thank you, Andreas, for turning me on to this wonderful zoom. And thanks to Tammy for directing me to Starlight Instruments for the adapter - a beautiful piece.


#8 andydj5xp


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Posted 17 January 2010 - 09:46 AM


thanks for the amazing report. I'm VERY glad that you have not been disappointed about this quite expensive zoom since you have purchased it just relying on my short notes only.

The Starlight Instruments adapter for sure is a beautiful piece of art. The main advantage over my solution is the ability to quickly change the zoom from astronomical use to using it with the Leica spotting scope. And there will be no danger of marring. IIRC this was the intention of Tammy.

OTOH, my solution is only about 40$ plus one hour of easy machine work. Also it needs about 10mm less intrafocal way. And if I'd have chosen nylon screws - I really didn't care - my solution would avoid marring also.

Bottom line: there are two different ways to adapt this zoom for astronomical use.


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#9 CounterWeight


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Posted 17 January 2010 - 01:42 PM

Very well done review of this zoomer! and Barlow used. Thank you very much.

#10 andydj5xp


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Posted 21 June 2010 - 07:53 AM

In order to get the discussion continued I'd like hearing about two topics:

1. 2"-adapter
Are there any experiences from other astronomers using the Leica ASPH zoom with either the mentioned Starlight adapter or with some kind of DIY solutions like mine? It would also be of interest if somebody got an adapter from APM. I remember the beautiful 2"-adapter from APM for my former Leica 22-7.3mm zoom which I purchased from Markus Ludes.

From some slightly OT-discussions within the Docter-UWA-12.5mm-thread about the Starlight adapter for the Leica I take it that telescopes with not that much intra focal way could have difficulties with focusing. And within this discussion there have also been some hints from APM about possible adapters.

2. Does anybody already has used the ASPH zoom with "fast" scopes (besides Brian's 20" f/5)? Since the design focal ratio of this zoom is f/5.2 (Leica Apo Televid 85/440) the zoom should well be able to handle faster light cones than from my f/7 refractor.


#11 APM M.Ludes

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Posted 24 June 2010 - 12:48 AM

I have a question : where can you buy this Zoom standalone ? I am a leica dealer, I have had to buy the expensive new 82 mm Spotter to get this zoom for myself. I heard a UK dealer sold it alone, so I contacted Leica again and asked if that is now available as listed in the dealer sheet and Leica declined. Leica stated during this year you cannot buy the eyepiece alone, maybe next year. When i confontred them with the single sale in UK, they answered in that case the UK dealer bought the set and have now the spotter laying around for 1 year till he can buy the single eyepiece

does Leica give me false info ?

so do you have any source where you can buy this eyepiece right away ?

thnks for info and help, since we have many customers on our waiting list and we cannot deliver

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