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Duovid Optical Construction

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Old Friday 19th July 2019, 04:25   #1
John A Roberts
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Duovid Optical Construction

Unique among the premium brands, Leica offers a binocular with a limited ‘zoom’ capability - the Duovid
More correctly it’s a dual magnification system, with the higher magnification providing a 50% increase in power

The Duovid was introduced in 2002 and comes in 2 models: 8+12x42 and 10+15x50
See both the attached specifications (indicating that each model has 11 lenses per side), and a drawn cutaway view of the x42 version which gives some idea of the internal construction

I recently came across 2 images taken from different angles, of an actual cutaway Duovid x42, that make the optical construction much clearer - and prompted this thread
The first image is from: https://michaels.com.au/blogs/camera...simply-amazing
And the second from: https://imgur.com/gallery/3XA9G3M

As can be seen, the construction comprises:
- 4 objective lenses in 3 groups (2, 1 + 1 focusing lens), and
- 7 ocular lenses in 4 groups (2, 1, 2, 2)
The first 3 groups in the eyepiece move in unison when the power is changed, with the rear stationary group sealing the end of the unit

** EDIT: after having had another look at the two images of the cutaway unit, and then comparing them to the drawn cutaway,
it seems that the first eyepiece group is stationary, and that only the middle 2 groups move
i.e. the middle 2 groups seem to be in a cylinder, that can slide inside a larger housing, that has the front and rear groups at the two ends **


The convenience of the Duovid's dual power - combined with high optical quality - comes with several limitations compared to comparable conventional binoculars:
- extra weight, smaller field of view and limited eye relief (measured on the x50 as 12 to 13 mm from the eye lens surface - see Roger Vine below)
- and of course cost
And as the Duovid is essentially a low production speciality item, many of the updates that have been made over the years to other Leica binoculars, have not been applied to the Duovid


While there’s not a lot of information available about the Duovids:
A) Roger Vine has provided a detailed review of the 10+15x50 (and comments on the 8-12x42) here: http://www.scopeviews.co.uk/LeicaDuovid.htm , and

B) Gijs van Ginkle has published transmission data about a 2010 production x42 unit
It’s from slide 32 of Gijs’ 2017 presentation on Multifunction Binoculars and Telescopes (comprising 111 slides and 19 MB) at: https://www.houseofoutdoor.com/verre...n-vergelijken/


John
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Last edited by John A Roberts : Saturday 20th July 2019 at 00:06.
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Old Friday 19th July 2019, 10:43   #2
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Just to repeat previous posts

I enjoy my Duovid 10+15x50s for distant birding of shorebirds and raptors and astro for eclipses with filters.
Very specialized and not all around, but good at what they do.

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Old Saturday 20th July 2019, 02:19   #3
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Very interesting information John - thanks for the thread

If the weight, limited Fov, and ER issues could be solved, I'd love a state of the art 7.5-15x (45 or 50). FL, HT glass, the works. The Uber bin could also include an IS button (ergonomically located !) that could be optionally engaged for hand holding at 15x.

If such a bin could be brought in under 750g (and with CFRP, etc there's no reason for it not to), with ER suitable for glasses wearers, and with at least 66 AFOV, I 'd be on it quicker than a seagull on a hot chip ! :)





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Old Saturday 20th July 2019, 04:49   #4
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Great info John!

I've always thought the Duovid is a beautiful binocular. I bet it's time intensive to make. I'd probably own the 8-12X42 if the eye relief were even 15.5mm.
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Old Saturday 20th July 2019, 09:19   #5
peter.jones
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My main binocs are duovid 8+12's.
I wouldn't necessarily recommend them to a birder, and the minimum focus is totally unsuitable for insects, but they work well for my uses, and my reason for buying them..

I do surveys for Marinelife on the channel ferries. The bridge of a ferry is a long way from the sea! and telescope/tripod aren't permitted.
The duovid at 12x gives that little bit extra power. In fact a team of 1 observer with 8x and me looking further out with 12x often yields good results. I definitely see and identify more storm petrels, than I did previously. Distant Divers in flight got easier etc.

Elsewhere, I have them at 8x, and switch to 12x in open habitat, or if I want to take a slightly closer look at something. 12x often squeezes an extra i.d. feature that wasn't visible at 8x.

I was slightly concerned when I bought them, and thought the measure of success or failure for me would be if I lost birds due to the binocs, either the narrower field of view, or when switching between the zooms. I don't believe it has, but it is another choice, which maybe complicates things further.

i.e. There's a bird, I need a closer look, do I zoom the Duovids up, take the scope of my back, or take a photo!!
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Old Thursday 25th July 2019, 03:34   #6
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I have a pair of Duovid 8+12X42 in green. They are great and I love them. The curvy profile is particularly appealing to me. The field of view is no problem, the eyecups are among the best that have been ever designed: their rear end bend innards and help keep the eyepiece closer to the eye.
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Old Thursday 5th September 2019, 23:06   #7
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To inspire some Leica Love for the Duovids, a pair of images:
- the first from Leica
- the second showing the alternative green version

The second is from the Dutch site ‘Twentse Vogelwerkgroep’, which has a series of binocular reviews by Jan Meijerink
I’ve attached a list of the reviews that can be found here: https://tvwg.nl/ovz-kijkers.shtml
and Google Translate produces comprehensible English versions

Jan’s review of the Duovids compares:
- the 8+12x42’s performance to an 8x42 Leica Ultravid (pre-HD), and
- the 10+15x50’s performance to a Canon 15x50 IS
see the attached table


John
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Last edited by John A Roberts : Thursday 5th September 2019 at 23:35.
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Old Friday 6th September 2019, 21:18   #8
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It makes sense that Leica would have been the one to do this. Back in the '90s they came out with a trifocal (not zoom) lens for the M rangefinder camera, 28/35/50mm. A unique, very elegant idea, given that the discrete finder frames didn't allow for continuous variation. (It was f/4.) This seems not to work quite so well in a bino though, just too many compromises for most of us. A reminder of the relative complexity of binos, I suppose.
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Old Saturday 7th September 2019, 17:48   #9
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I sold mine!
I tot the 10-15 in use for 5 years and I think it is outdated nowadays
It is heavy , has low FOV and horrible for glass wearers
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