Leica 7 X 42 Ultravid (1 Viewer)

John Russell · Jun 13, 2013

ceasar said:
I can't see any on my 7x42 SLC B. In fact it has remarkably good edges.

Bob,

Yes, the edge sharpness on the SLC is certainly better than most, but there is still some astigmatism.

Btw, I found this: http://www.juelich-bonn.com/jForum/file.php?9,file=769,filename=image.jpg on a German forum.
It is probably the same level as on my example (2003 manufacture, dielectric prism coatings but pre-Neu).
Today's coatings are much more extensive and in some cases matched to the refractive indices of the individual lens elements, but nevertheless on this fairly simple design there were a total of 83 coatings per barrel!
Interesting to see too that the "focussing element" is really a shifting objective with a weak converging lens in front to seal the bin.

John

henry link · Jun 13, 2013

That's a very interesting link, John. I don't read German, but it appears to show which surfaces are coated with each coating type and how many layers are used in each coating formulation. So, Swarodur is a 4 layer coating, Swarotop and the phase coatings are three layers and Swarobright is 30 layers. Is that correct?

I recall being told way back in the 1980's that Swarotop used 3 layers. Apparently that number hasn't changed, but the color bias of the stuff now called Swarotop is much improved. It's also interesting to see that the cemented surfaces, which are usually uncoated, apparently have a single layer coating.

Henry

henry link · Jun 13, 2013

On the subject of evaluating off-axis astigmatism, I would just add to John's comments that pupil position has a big effect on whether an observer will see astigmatism, including in a grid pattern.

I can choose to see a lot or hardly any astigmatism in the same binocular, depending on how I move my eye to examine the field edge. If I choose a pupil position that maximizes the vignetting of off-axis exit pupils then the rays that cause the astigmatism will be blocked from reaching the eye and the astigmatism will be visually cancelled in any binocular, no matter how astigmatic it really is. I think that kind of pupil position is often unconsciously assumed when people look toward the field edge at 3:00 or 9:00. The true instrument astigmatism is most accurately revealed by trying to keep the eye's pupil centered on the optical axis as the eyeball is swiveled to examine the field edge in a way that keeps off-axis vignetting to approximately the same level it is when the eye is looking straight through the field center. I find that easier to do when I rotate my eye down toward 6:00. The point is to be aware of how the way you examine something can affect the way it looks.

Also keep in mind that if you have any astigmatism it will cancel and reinforce the instrument astigmatism at different points along the field edge.

John Russell · Jun 13, 2013

henry link said:
That's a very interesting link, John. I don't read German, but it appears to show which surfaces are coated with each coating type and how many layers are used in each coating formulation. So, Swarodur is a 4 layer coating, Swarotop and the phase coatings are three layers and Swarobright is 30 layers. Is that correct?

I recall being told way back in the 1980's that Swarotop used 3 layers. Apparently that number hasn't changed, but the color bias of the stuff now called Swarotop is much improved. It's also interesting to see that the cemented surfaces, which are usually uncoated, apparently have a single layer coating.

Henry

Henry,

"Schichtenpaket" could be loosely translated as "layer package", so the balsam or cement is counted as one of these. I don't think there is any additional coating at positions 4, 14 and 19, though I vaguely recall that Pentax have used coatings on cemented surfaces - XW eyepieces?

Otherwise your interpretations are correct. The Swarobright is quoted as approximately 30 layers. Perhaps Swarovski were unwilling to divulge precise details. I'm sure there were improvements with the advent of the SLC Neu.
My wife's 7x42 Meostar (replaced last year by Meopta with a new one after the rubber armouring had split on the old one) has superior coatings to my old SLC, though I believe Meopta still use a silver coating on the prisms.

I wonder if it is possible to make "Easy to clean", "Lotutec", etc. as tough as Swarodur or other hard coatings for objectives and eyepieces, or are they the same material with a different surface quality? It would be interesting if you have any information on this.

John

henry link · Jun 13, 2013

John,

Thanks for the clarification. Yes, the cemented surfaces in the XW eyepieces are coated. I'm afraid I can't add anything about the durability of "Easy to clean" coatings.

Henry

Edit: I also notice that the surfaces facing the air space between the prisms are apparently given the same Swarotop coating as other surfaces even though they function for both transmission and internal reflection. I recall some discussions here of an old Swarovski technical paper that suggested those surfaces require a compromise coating to fulfill both roles.

ronh · Jun 14, 2013

Wow John, this really makes one appreciate the modern binocular.

As Henry says, in the 80's Swaro optician Konrad Seil published a paper that revealed a difficulty with coating the surfaces that do double duty. At that time, only a single layer could be used or the optical quality suffered. Now, those surfaces get the full multilayer treatment. That's progress, and another couple percent in transmission. It adds up.

Ron

brocknroller · Jun 14, 2013

ceasar said:
John,

Thanks for that information on using a tripod and a grid pattern to see it. That's good advice. I will remember it and remind Brock of it when he forgets it.

I can't see any on my 7x42 SLC B. In fact it has remarkably good edges. Field curvature is small.

Bob

Bob,

It could be your astigmatic eyes cancelling the SLCs astigmatism the way they do the FL's.

I have mild astigmatism in one eye, but if a bin has 25% astigmatism, I can easily see it handheld, particularly a 7x bin, I don't need to mount it. I have a 9x63 roof with A/K prisms that has about 15%-20% astigmatism at the edges. During the day, depending on the lighting, I might not notice it unless I'm looking at the edges or if I move an object toward the edge, but using it on the night sky, there's no mistaken the astigmatism because the edges cannot be refocused and stars are completely out of focus. That's completely around the field of view, not just in certain clock handle positions. IOW, it's not "hairy eyeball" astigmatism, it's the real deal.

John and Henry ("You can hear John Henry's hammer ring") cite the reasons why there can be differences in what's observed between two users. However, AFAIK, the only way both you and Frank could both be right in your assessments is if the FL has both field curvature and astigmatism.

Your astigmatic eyes or eye position might be able to negate the astigmatism, but if the bin doesn't have field curvature, you won't be able to refocus the edges with a nudge of the focuser. If you can cancel the astigmatism, the edges would be sharp, nicht wahr, John?

Brock

John Russell · Jun 15, 2013

brocknroller said:
If you can cancel the astigmatism, the edges would be sharp, nicht wahr, John?

Brock,

To quote Rutten: "Astigmatism is probably the most difficult aberration to understand. It exists whenever there is a difference between the optical power of the system in the tangential plane and the sagittal plane."

I don't fully understand it either but believe it has constructional rather than manufacturing origins (tolerances), i.e. hardly any SVs have it but all FLs do. ;-)

Astigmatism of the eye, however, is caused by differing radii of the cornea in different planes. So I believe that if one suffers from astigmatism one would not be able to obtain a sharp image on the optical axis but with an astigmatic instument might be able to obtain a sharp image off axis, but then only at a specific radius on one transverse plane.

John

Binastro · Jun 15, 2013

I can only talk from personal experience, but I have a 12 x 45 Russian binocular which has slight astigmatism in one barrel which exactly is cancelled by the small astigmatism I have in one eye.

The star images centrally in both barrels used normally are circular and essentially perfect except that the star images are not small points but slightly expanded as occurs in most binoculars.
Really small star images are rare in binoculars although you get it in good telescopes.

I of course checked the images in both of the barrels of the 12 x 45 with each of my eyes one of which has almost no astigmatism at all.

It may be that theoretically what you're saying is correct but I can only speak from actual observation, and I am an experienced observer.

My astigmatism has changed and the angle of astigmatism has changed over the years so that this binocular may no longer display the same star images as when I bought it.

My astigmatism is not great but with the eye doctor I often get the angle down to just over 1° accuracy. We spend at least one and a half hours testing my eyes every year.

henry link · Jun 15, 2013

John and I are talking about off-axis astigmatism. Axial astigmatism can be completely corrected by a complimentary astigmatism in the eye, but the angle of off-axis astigmatism rotates with different clock positions on the field edge. So, off-axis astigmatism can be corrected for only two clock positions on the field edge by a complimentary eyesight astigmatism, while at the same time it's made worse for the two clock positions at 90º angles to the corrected ones.

I won't be at the computer for a few days, but I'm sure John can explain anything more that needs explaining.

Henry

ceasar · Jun 15, 2013

henry link said:
John and I are talking about off-axis astigmatism. Axial astigmatism can be completely corre.......

.................................................

I won't be at the computer for a few days, but I'm sure John can explain anything more that needs explaining.

Henry

Good move Henry!:-O

Bob

Binastro · Jun 15, 2013

.. Dear John and Henry,
just after I wrote the above post I realised that we were talking about different astigmatism but I went to have something to eat so did not corrected it immediately.

I realise that you are talking about off axis astigmatism using perfectly spherical elements, whereas the problem with my binoculars was that either the elements were not spherical or possibly the glass was not homogeneous.

Thanks.

gulf1263 · Jun 16, 2013

Leica 7x42 Ultravid

Just to try and bring the posts back on topic, I have compared the Leica 7x42 Ultravid HD with the Swaro 7x42 and IMHO the Leica is better, YMMV.
The view is superior, better color fidelity and excellent center sharpness.
Some people don't like the "clinical view" through the Leica, the Swaro was "warmer" but using my color checker the Leica was more accurate.
Again, YMMV.
I prefer the view through the Leica and appreciate the much lighter weight and more compact size.
Art

ibramr · Jun 17, 2013

I had the pleasure to compare the Ultravid (HD) and Zeiss FL 7x42 side-by-side, then the Swarovski alone. It was a very close call between the Leica and the FL--the latter won the day because a) it was brighter, and b) focusing was smoother. The legendary contrasty colors of the Leica were superb though. I must also say that leaning towards the Zeiss had to do--at least in part--to the fact that I am myopic and the diopter range of -4 helps a lot.

The Swarovski SLC New 7x42 was also excellent--albeit noticeably heavier. Very accomplished pair, really, in terms of color and clarity. However from memory, and comparing it to the Leica, I would have still preferred the Leica though. This is because of the weight concern, and the ease of the Leica's handling characteristics.

There is no question that the 7x42 is a very enjoyable format. Any of the above three is bound to give endless of hours of joy. The differences are de minims, and only felt in a direct comparison among them a the same time. I doubt very much that these difference will be remembered in the filed (with the exception of the diopter range). Enjoy in good health.

Anansi · Aug 22, 2013

Does the 7 X 42 UV HD have more CA near the edges that the non HD version? According to Allbinos, the 8X 42 V+UV HD has more CA on the edge. Has anyone compared a non-HD and HD UV 7 x 42 Leica. Just curios.

Anansi

Leica 7 X 42 Ultravid (1 Viewer)

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