I ordered an SF 10x32. I wanted the bigger 7.5 degree FOV and I don't think it will have much field curvature from what I hear.
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I never met a 7x I liked until I met the Zeiss FL 7x42. (1 Viewer)
- Thread starter Dennis Mau
- Start date
henry link
Well-known member
Barlow lenses like the one in the 10x32 FL do act very much like field flatteners. The 10x32 and 12x50 Leica Ultravids eyepieces also have doublet Barlows added to the field end to boost the magnifications from the 8x32 and 10x50 models. I would expect the 10x32 and 12x50 Ultravids to also have superior off-axis corrections compared to the un-Barlowed Ultravid models. However, the eyepiece design of the Zeiss 32mm SF does not simply add a Barlow to the 42mm design. The eyepiece designs are completely different from stem to stern, so no similar prediction is possible.
It's impossible to evaluate the field curvature of the 7x42 FL without first considering the behavior of its off-axis astigmatism. The tangential and sagittal foci of the off-axis astigmatism in the FLs curve away from the plain of the central focus in opposite directions, creating what amounts to two opposing tangential and sagittal field curvatures that are mirror images of each other, with the central focus plain at approximately the midpoint between the two. As a result the field curvature cannot be focused out with the binocular focuser or accommodated away by the eye.
It's impossible to evaluate the field curvature of the 7x42 FL without first considering the behavior of its off-axis astigmatism. The tangential and sagittal foci of the off-axis astigmatism in the FLs curve away from the plain of the central focus in opposite directions, creating what amounts to two opposing tangential and sagittal field curvatures that are mirror images of each other, with the central focus plain at approximately the midpoint between the two. As a result the field curvature cannot be focused out with the binocular focuser or accommodated away by the eye.
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Good posts, Henry! So you predict the FL 7x42 will have some field curvature and the FL 10x32 will have less because of the Barlow lenses in the eyepiece. Why would the FL 10x32 use a Barlow and the FL 7x42 doesn't. Is it because the 32mm FL is a totally different design than the 42mm FL, like the SF 32mm and SF 42mm binoculars? Do any of the other FL's use a Barlow in the eyepiece?
"In my interview with Thomas Steinich of Zeiss ( Interview with Zeiss Senior Optical Scientist ) you can find hints at how developing a 32mm unit is not as simple as making the lenses a little smaller in diameter. If you look at the images of the internals of SF 32 on the Zeiss website, and of sectioned SF 42s on the internet, you would be struck by the following differences. SF 42 has an eyepiece consisting of 3 doublets and a singlet, whereas SF 32 appears to have 5 doublets and 1 singlet. At the objective, SF 42 has a fixed doublet and a moving singlet focusing lens, but SF 32 has a fixed singlet objective and a doublet focuser. In other words, SF 32 is significantly different from the 42. The 10x32 has a field of view 8.3% wider than the 10x42 (yielding an area of view 17.4% bigger) and eye relief has increased from 18mm to 19mm. It is not easy to pull off both of these at the same time, so I guess that explains some of the complexity of the eyepiece."
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tenex
reality-based
Possibly this is why, having used a 10x32 BN for years, I was unimpressed by Leica 42s. And it may not be coincidental that we wound up with a 10x32 FL also, and just lately 12x50 UV, all of which I think perform very well.
As to astigmatism: whenever I read about it, I wonder how it can be possible to correct at all, let alone to an acceptable level along with other aberrations.
Very interesting, the same happens to other binos too? Like SF, Nl pure, etc. That we can say that their 10x32 version tends to be more sophisticated with a better corrected field?
John A Roberts
Well-known member
Picking up on Henry’s comment in post #62 as to the significant difference between the SF x32 and x42 designs,
by way of illustration:
Top image of the x42 from Gijs in posts #26 to 29 at: Swarovision Zeiss SF side by side
Bottom image of the x32 from Zeiss (not to scale)
John
by way of illustration:
Top image of the x42 from Gijs in posts #26 to 29 at: Swarovision Zeiss SF side by side
Bottom image of the x32 from Zeiss (not to scale)
John
Wow! The SF 32mm is much more complex than the SF 42mm. It is funny, the 32mm is not more expensive than the 42mm. I guess the lenses are smaller in diameter in the 32mm, making it less expensive to manufacture. Nice pictures, John. Interesting to study the difference between the two.
I see less lens elements in the eyepiece in the case of the 32mm (6 elements vs 7 for the 42mm). In the diagram, all lens doublets are detached and give the illusion of more quantity.
If you are counting the doublets as two elements, the SF 42mm has 7 lens elements(3 doublets and a singlet) whereas the SF 32mm has 11 elements(5 doublets and a singlet).
"In my interview with Thomas Steinich of Zeiss ( Interview with Zeiss Senior Optical Scientist ) you can find hints at how developing a 32mm unit is not as simple as making the lenses a little smaller in diameter. If you look at the images of the internals of SF 32 on the Zeiss website, and of sectioned SF 42s on the internet, you would be struck by the following differences. SF 42 has an eyepiece consisting of 3 doublets and a singlet, whereas SF 32 appears to have 5 doublets and 1 singlet. At the objective, SF 42 has a fixed doublet and a moving singlet focusing lens, but SF 32 has a fixed singlet objective and a doublet focuser. In other words, SF 32 is significantly different from the 42. The 10x32 has a field of view 8.3% wider than the 10x42 (yielding an area of view 17.4% bigger) and eye relief has increased from 18mm to 19mm. It is not easy to pull off both of these at the same time, so I guess that explains some of the complexity of the eyepiece."
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tenex
reality-based
I just noticed that only FL 42 is shown in this initial brochure from 2004. When were the 32 and 56 introduced?
henry link
Well-known member
2005 sounds right for the 32mm FLs, but the 56mm models were introduced in the late spring of 2006. I bought mine in March of 2007.
henry link
Well-known member
I gave up trying to figure out the pattern of lens elements and groups from that Zeiss cutaway of the 32mm SF. The general visual confusion caused by the complex glass reflections from the lenses seems to be intentionally designed to make the eyepiece formula impossible to read. I can say that it doesn't resemble any other binocular eyepiece.
The 42mm cutaway is much clearer: essentially a modified 6 element Erfle (the three doublets) with a simple singlet field flattener (which resembles Nikon's use of modified 5 element Konig with simple singlet field flatteners.)
I should mention that many modern eyepieces for astronomical scopes, spotting scopes and binoculars
already include dedicated Barlows now as part of the overall design for purposes of magnification modification in different models and field flattening. The use of Barlows in 10x32 FLs and 10x32/12x50 Ultravids was unusual at the time they were designed. Most Leica Ultravid/Trinovid and Zeiss FL/HT models used variations on 4 and 5 element Konigs with no Barlow. In those days the Leica/Zeiss designers thought they didn't need any better off-axis corrections.
tenex
reality-based
Presumably then these three higher-magnification models weren't even meeting that standard, without the Barlows? And the challenge of the 10x32 (vs 42) was the shorter focal distance? (It was also a late addition to the Trinovid line, while 12x50 was one of the original models.)
Why do you think the Leica UVHD+ 7x42 is the gold standard? It only has an 8 degree FOV, compared to the 8.6 degree FOV of the Zeiss FL 7x42, and not nearly as good of CA control.
I find anything under a 60 degree AFOV to be tunnel like, and that is what I found both the UVHD+ 7x42 and the EDG 7x42 to be with their puny 8 degree FOV and 56 degree AFOV.
IMO, that is the major weak point of most 7x42 binoculars. If they made one with a 10 degree FOV, people would buy more and they would supplant the 8x42.
Also, the Leica UVHD+ 7x42 has lower transmission than the Zeiss FL 7x42, so it is not nearly as bright or sharp on-axis and has considerable CA on the edge.
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Elpha8888
Well-known member
Quite right, tbh and from what I can remember I didn't find the fov of the Leica too distracting, the Leica has that magic, a serene beauty to the image. The Zeiss from what I can remember was clinically sharp and oh so bright. Both are superb, the Leica is the one I remember more fondly.
Leica's have more saturated colors, so if you like a lot of color, you will like a Leica. Leicas are a warmer view because their transmission curve tends to be towards the red end of the spectrum. The trouble with a lot of Leica's is they have considerable CA on the edge that is noticeable. If you don't like CA, stay away from Leica's.
MiddleRiver
Well-known member
Leica also has best build quality IMHO.
I noticed the CA in Trinovide HD. Not on others...
Maybe it is 'perceived' build quality, but not 'actual' build quality. In Allbinos Durability test, the Zeiss FL scored 1st place. The Leica UVHD+ 8x42 failed miserably on the waterproof qualities test and scored 12th place overall. It could be one bad sample, but shouldn't every sample pass the waterproof qualities test?
Endurance test of 8x42 binoculars - Leica Ultravid 8x42 HD - AllBinos.com
The best binocular tests on the net. The comprehensive database of binoculars with their parameters and users opinions. Interesting articles and comparisons.
Endurance test of 8x42 binoculars - Final results and summary - AllBinos.com
The best binocular tests on the net. The comprehensive database of binoculars with their parameters and users opinions. Interesting articles and comparisons.
"Waterproof qualities
According to the specifications, the Leica Ultravid HD series of binoculars is waterproof up to a depth of 5 meters. We don’t hesitate to say the producer simply doesn’t tell the truth.
The binoculars we tested didn’t manage to survive a submersion in knee-deep water for half an hour. After such an operation, the device was completely drenched and most of its functions stopped working.
It is a huge fault for such a renowned manufacturer because it is expected that they are honest, and their product perform exceedingly well. Meanwhile, the Ultravid HD didn’t manage to fare as well as the Delta Optical Forrest II, which costs a measly 400 PLN or the Pentax DCF 8X43 ED, which was supposed to be only splash-proof!
The photos below show in what miserable state the Leica was after we took it out of water. One of the tubes was fogged up, in the other one the water sloshed merrily about… It is not nice to kick the defeated opponent, but we must add here that even the window with a scale, positioned on the focus wheel, was completely flooded.
A real tragedy and a complete failure!"
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