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Ultravid comparison? (1 Viewer)
- Thread starter phyllosc
- Start date
elkcub
Silicon Valley, California
phyllosc said:
No, but I've compared the Ultravid 10x42 with the Trinovid 10x42. IMO the Ultravids were much nicer to handle, balance and focus. The weight is more agreeable as well. My guess is that would also apply to a x32 comparison as well.
I have evaluated the 10x32 on its own merit , and compared it with Swaros and the 8x32Bn. I particularly dislike the extreme pin cushion distortion on both Trinovids. I can't recall if it's as bad on the Ultravid.
Hope that helps,
elk
phyllosc said:
Dave,
See
http://www.monkoptics.co.uk/General/about-binoculars.html
for a simple explanation of distortions.
Supposedly, Leica introduces distortion into their bins, however, I've never known anyone claim they like it. I know I don't! My guess would be that a flat, sharp FOV is preferred.
John
elkcub
Silicon Valley, California
John Traynor said:
Yup, that's a good place to see a picture of it. I've attached a poor scan of pg. 97 from the "Leica, The Program" brochure of a few years ago. (Sorry about the quality, but you can print it.) Under the picture of pincusion distortion is says "Creates a natural pictorial impression when a binocular is panned across a scene: pin-cushion correction in the optical system of Leica binoculars." Wow! Pin-cushion "correction." Right! That didn't pan out so well. :'D
elkcub said:
I have a 8x32BA and I have never been bothered by that distortion. If anything, it is very slight, particularly since it would mostly be apparent when looking at buildings and other straight structures. However, when I bought the precursor to that 8x32 BA in 1975 or so, a 10x40 model, I recall having experienced considerable irritation when panning with the "non-distorted" Zeiss compared to the Leica. Thus, there must be some truth to the Leica philosophy. I had no idea about it at the time; rather, I felt that there was something wrong with the Zeiss.
Robert
Curtis Croulet
Well-known member
I'm no expert, but IIRC an optical designer has to decide between a flat field and distortion, or a curved field and no distortion. You can't have both a flat field and no distortion. The marketing department may tout pincushion distortion as a desirable feature, but really it's just an inevitable result of another design choice.
Curtis Croulet said:
Curtis,
I'm not sure I follow your logic. There are bins with relatively flat fields and minimum distortions. My SE has so little pincushion it's insignificant, it's very flat, and extremely sharp across the FOV. Leica's argument that you need pincushion for comfortable panning is disproved by the SE.
John
Curtis Croulet
Well-known member
John Traynor said:
I was told this by one of the top optics experts in the US, and if you read through years' worth of test reports of eyepieces, camera lenses or just just about any other optical device, you realize that you can't have everything at once. However, since you seem to have some expertise in this area, perhaps you can give us the real scoop. I've only looked through an SE once, very briefly, so I can't comment on it.
elkcub
Silicon Valley, California
Swissboy said:
Hmmm. Interesting. I admit to observing building architecture a lot, and often pan from rooftops. However, I prefer a flat field (i.e., rectilinear), and wouldn't want binocs only for field use. That's just my personal view.
Leica would do well, however, to provide substantiating literature before simply asserting that pin cushion "correction," or any other design feature, reduces an arcane problem.
-elk
Pinewood
New York correspondent
Dear Elk,elkcub said:
Is not the term "flat field" taken to mean that the binocular focuses everything in the same plane, from edge to edge? This avoids the problem of "curvature of field," where objects in the same plane, near the edge, are out of focus when the center area is in focus.
Happy bird watching,
Arthur Pinewood
elkcub
Silicon Valley, California
Pinewood said:
Hi Henry,
Sorry about my less than exact (or incorrect) terminology. I think of that as a flat focus. Here I only meant flat field in the sense of presenting straight lines that are not curved out at the edges (i.e., pin cushion). How optical designers might go about that trick, or what compromizes are involved, is beyond me.
I think the kind of flat field you're referring to is the same sort of thing as a macro copy lens, which should retain all points in focus on a flat surface. In other words, at some considerable expense, it compensates for the change in distance as one goes from the center to the extremes. Many folks use their macros for general photography. I'm not sure if that's because of the flatness qualities they have for copy work or because such lenses simply have more resolving power. For normal photography my impression is that no one could perceive a difference in off-axis focal point anyway.
Using flatness in this sense, do you feel that it's a good property for a binocular? Is it related optically to the pin cushion effect that is the bane of camera lenses—but which Leica says is good for binocular use?
-elkcub
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elkcub
Silicon Valley, California
On further thought, Henry, I'm a bit confused about references to a flat field in a binocular context — implying everything is in focus across the image. Maybe I'm misreading. I would think the reason the center is in focus and the edge often not, is that the focusee (the bird) is usually placed at the center by the focuser (the birder). If other objects are in focus elsewhere in the field it's either because (a) they are the same radial distance away or (b) there is sufficient DOF in the system. What am I missing here?
-elk :h?:
-elk :h?:
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elkcub
Silicon Valley, California
Curtis Croulet said:
Curtis,
I fully agree in this sense. To photograph a flat field in focus it is necessary to compensate for chages in radial distance to all points on the surface. That compensation is a "distortion" introduced to produce a desired effect in the photo. To my knowledge, the eye has no such flat field compensation — but it does have a curved projection surface that differs from a camera's film plane. So it's similar.
-elk
Curtis Croulet said:
Curtis Croulet said:
Curtis,
Since you don't have much time logged on the SE you may not appreciate its beauty. Ask any SE user and they will tell you that pincushion is almost non-existent, the field is extremely sharp across a very wide "sweet spot", edges can be focused tack sharp, and the resulting view is very restful, pleasing and addictive. Yes, there are curvature "distortions" in the SE, but they are insignificant in the field.
I've used the SE for countless hours of observation and I can tell you it is one amazing piece of work. I have seen nothing comparable in overall visual quality.
I often get the impression people don't want to hear about the SE's qualities and I find that disappointing. Consumers should prod manufacturers to produce the very best and saying good things about a product seems as appropriate as commenting on the negative. It appears none of my comments, good or bad, will be accepted at face value.
Finally, I am not, nor have ever claimed to be, an optical expert. I am an end user with a pair of eyeballs that still work. I report what I see, and what I see in the SE has, so far, not been matched by any other binocular. I believe that’s called an opinion.
John
Pinewood
New York correspondent
Dear Elk,elkcub said:
Although I am not Henry, the problem is the inability of a spherical lens to focus everything in a plane on the same plane. Using your photographic analogy, even when focussed at infinity, distant objects at the corners of the film, or sensor, are not as sharp as those at the center. Stopping down improves the resolution at both the center and the edges but stopping down is not an option for binocular users. You are quite correct that the curved retina, the plane of focus, of the human eye compensates for this problem. Field flatteners and other design options are used as part of the design compromise. Aspherical lenses in the ocular may be a newer solution.
I tried the Fujinon 7x50 FMTR-SX, which is well known for a flat field, but found that the distortions of buildings, they looked like they were falling back, very disturbing.
Happy bird watching,
Arthur Pinewood
Happy bird watching,
Arthur Pinewood
I think there is a bit of confusion.
When I first heard Leica say that they had put in rectilinear distortion on purpose, I thought that they were pulling a fast one. However, the presence of rectilinear distortion in an optic is indeed a feature and not a flaw, and incidentally is unconnected with curvature of the field. The optical designer can completely correct for either angular magnification distortion or rectilinear distortion, but not both. The former is more important for astronomy and the latter for birding. In practice the designer reaches a compromise. Hopefully someone can give a simple explanation for angular magnification distortion but its presence leads to objects looking stretched.
When I first heard Leica say that they had put in rectilinear distortion on purpose, I thought that they were pulling a fast one. However, the presence of rectilinear distortion in an optic is indeed a feature and not a flaw, and incidentally is unconnected with curvature of the field. The optical designer can completely correct for either angular magnification distortion or rectilinear distortion, but not both. The former is more important for astronomy and the latter for birding. In practice the designer reaches a compromise. Hopefully someone can give a simple explanation for angular magnification distortion but its presence leads to objects looking stretched.
Curtis Croulet
Well-known member
Yes, Leif, your explanation about angular magnification distortion vs rectilinear distortion is what I heard from the "expert" (several times in different venues, in fact). You're right -- it had nothing to do with a "flat field." Thanks for the clarification.
This is exactly my experience too - even with the same examplesSwissboy said:
. Some of us do seem to be irritated by the barreling effect more than the pincushion.To get back on topic...
I have briefly tested the 10x32 Trinovids and 10x42 Ultravids. As usual - I completely agree with Kimmo Absetz's (Alula test 1/2004, http://www.alula.fi/GB/index.htm) comments that the Ultravids are very bright but suffer from noticeable edge softness compared to the 10x32 Trinovids. I am not sure but I would guess that the 10x32 Ultravids use the same (ie. the "better") eyepiece. IIRC even the eye-relief is the same. The main differences between the 10x32 Ultravids vs. Trinovids are the dielectric vs. silver prism coating, eyecups and the body material. I would guess that the image quality is very similar (the Ultravids maybe slightly brighter).
Ilkka
elkcub
Silicon Valley, California
Pinewood said:
Oops, my sincere apology for addressing you as Henry; which also motivates me here and now to apologize to Henry. Sorry, Henry, for using your name! I feel better now. Thanks.
Arthur, my confusion relates to your statement: "... the 'problem' is the inability of a spherical lens to focus everything in a plane on the same plane." Why is this a problem? Generally speaking, spacially located points at a uniform radial distance equal to the eye's (momentary) focal distance tend to be in focus on the spheriod retinal surface, particularly the narrow foveal area. (The eyeball is not exactly a sphere.) All points on a flat surface perpendicular to the line of regard do not appear in focus in normal vision, i.e., because distance increases with off-axis angle. So why would one want to design a binocular to keep everything in focus on a flat plane? Would that not introduce perceptual problems of its own?
-elkcub
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