Trinovid BAs still a 'sweet spot' among Leica binoculars? (1 Viewer)

[tenex]

Here is the original (2005) post reporting this alleged phenomenon:

I have two pair of Leica Trinovid 8x42 BA. Externally they look identical. Comparing them, I noticed that they did not produce identical images. One pair has a bluish tint to the coatings, and the other has an amber tint. The blue pair produces a brighter, whiter image that requires pinpoint focusing. The amber pair has a darker image, but seems to allow for less focusing at similar ranges. What I mean by focusing, is that with the amber pair I can shift my view to a different object at a different distance, and it is not as badly out of focus as it would be with the blue pair.

I repost this in a form that allows following the link, to learn that this person posted a few dozen messages on BF 15 years ago that cannot be said to be of a technical nature, and gave no indication here of any particular care in measuring or verifying this purported difference in perceived DOF. No one seems to have found the report interesting enough to pursue or inquire further into at the time, yet here we are now, asking how to explain it.

So two possibilities exist. First, it's simply a confusion or mistake on his part, which he never followed up with proper investigation. (I'll put my money there, as I suggested above.) Second, it's a real phenomenon which many more careful observers on BF might have been expected to report over the years (as they have not), and a plausible explanation for it would have to exist. You come a bit closer to enunciating one here:

The eye, using a simple lens, suffers from longitudinal chromatic aberration, so its ability to accommodate for different distances in a view can depend on the distribution of colors in the light involved.

This is still curiously vague, but I might take you to be suggesting that shorter wavelength light, having greater refraction, would present a greater challenge in focusing, and therefore the "bluer" Trinovid could seem to have less DOF? (What would that mean for Swarovskis vs Leicas today?) But how much bluer is it really? You're inviting us to envision the transmission curve for Trinovid BA 42, which Allbinos didn't measure back then but probably ranged between 80~90% across the visible spectrum, and imagine that tiny variations in overall color within that narrow range due to coating differences can have easily perceptible effects on DOF which however have only been noticed by the incomparable "bodromarsh" in the history of this forum. That is what strikes me as absurd, although I'm prepared to review any evidence you might have to the contrary but are for some reason withholding.

 

[casscade]

It’s absolutely a real phenomenon imo, I’ve had more than 100 samples over the years of most every alpha from the late 90’s up until recently. The reason I posted this is because for what ever strange reason I’ve experienced the exact same thing.

I have 2 current 10x50 ba’s, one that has as vivid/white/crystalline view similar to a new swaro slc or Zeiss HT, the other one, same 10x50ba, has a warmer richer look and a bit higher contrast, again both 10x50 ba’s.

BA 1 it feels like it has almost turbo focus compared to BA2, meaning you have to be very precise for that perfect focus, the other pops in and on point almost effortless and seems to stay in focus over a broader area/range with less fuss, one is from 99 and one from 2000.

Maybe it’s just perception and the difference in contrast, it’s really the only thing I could imagine it being, but it does exist, even if only being perceived.

After all, what I perceive is what’s real and all that matters imo. Also to note, and not that it matters, the vivid one has blue/green hues on the lenses where the warmer one is magenta/yellowish to dirty green.

 

[LarryO]

...
So two possibilities exist. First, it's simply a confusion or mistake on his part, which he never followed up with proper investigation. (I'll put my money there, as I suggested above.) Second, it's a real phenomenon which many more careful observers on BF might have been expected to report over the years (as they have not), and a plausible explanation for it would have to exist...

You're inviting us to envision the transmission curve for Trinovid BA 42, which Allbinos didn't measure back then but probably ranged between 80~90% across the visible spectrum, and imagine that tiny variations in overall color within that narrow range due to coating differences can have easily perceptible effects on DOF which however have only been noticed by the incomparable "bodromarsh" in the history of this forum. That is what strikes me as absurd, although I'm prepared to review any evidence you might have to the contrary but are for some reason withholding.

Some comments:

1. There might not be large numbers of birdforum members who have possessed multiple examples of the same alpha-binocular model displaying different coating colors, let alone members who have had the examples in hand at the same time. That could account for there not having been similar comparative reports from "many more careful observers." Nonetheless, there have been more than one.
2. There are actual transmission spectra for a Trinovid BN 10x42 and an Ultravid (non HD) 10x42 in post #4 of the thread 'Coatings Questions' <Coatings questions>, no "envisioning" needed. I cited those in post #50 of the present thread. The spectra do display differences, and the post discusses ideas about which of those might affect perceived brightness, contrast, and overall color.
3. The birdforum threads are filled with reports of visual differences among binocular models, including differences possibly accounted for by differences of lens coatings. Despite the usual absence of technical measurements in those reports, I find the experiences of users conveyed in them, including those of "the incomparable 'bodromarsh,'" helpful and interesting; I suspect other birdforum readers also do.
4. I am not "withholding" any extra "evidence," am puzzled by the suggestion that I might be, and can't think of a reason why I would.

Larry

 

[NDhunter]

I suppose that means that individual opinions are a "missmash", as far as coating colors go.

There is no way of knowing what objective coating AR reflective colors really mean. Each mfr. has there own formula, and
how they translate to what you see through the ocular is what counts.

If this does not make sense to you, that is how it is.....

Jerry

 

[LarryO]

....
There is no way of knowing what objective coating AR reflective colors really mean. Each mfr. has there own formula, and
how they translate to what you see through the ocular is what counts.

If this does not make sense to you, that is how it is.....

Jerry

Jerry -

It makes perfect sense. As mentioned in my post #23 here, and again in post #44, at least one coatings engineer also said that little could be deduced from reflected coating colors about actual spectral transmission and that the reflected colors could, to some extent, even be chosen to satisfy marketing fashion, with little effect on transmission! That is why I find value in the reports from actual users about the views through different specific models, along with the reflected colors that happen to be on the models involved. While the reflected colors may not offer insight into the transmission spectra, they might provide clues about the production-run groups (glass, fashion, etc.) to which specific examples belong.

Larry

 

[tenex]

BA 1 it feels like it has almost turbo focus compared to BA2, meaning you have to be very precise for that perfect focus, the other pops in and on point almost effortless and seems to stay in focus over a broader area/range with less fuss, one is from 99 and one from 2000.

Interesting. So how does the sharpness of these two compare when optimally focused (as best you can determine for #2, perhaps over multiple attempts) on the same object? (And no insult intended, can you actually tell? I can't always, except for very distant targets.) One could simply be a lemon. Have you made these comparisons carefully at the same focal distance, rather than merely stating a general impression from memory, as bodromarsh also did? It's still not obvious that what either of you is talking about is depth of field at all.

There are actual transmission spectra for a Trinovid BN 10x42 and an Ultravid (non HD) 10x42 in post #4 of the thread 'Coatings Questions' <Coatings questions>... The spectra do display differences, and the post discusses ideas about which of those might affect perceived brightness, contrast, and overall color.

Not, however, depth of field. And you still have provided no putative reason how or why they would affect depth of field, leaving me quite comfortable concluding that (contrary to any impression created above) you know of none.

 

[casscade]

Here’s the strange thing, again it has to possibly do with contrast or perceived contrast possibly, idk. When I put both on usaf charts or a Zeiss resolution chart they measure identical. In certain light though like bright sunlight the warmer pair seems to be a bit sharper but I think it’s more the contrast not measured resolution.

If just seems like you pick up pin point focus easier and over a broader range in the warmer pair. It’s really odd, I wish I had multiple people to look for themselves to get their perspective.

The more vivid ba does seem to show heat and mirage more so than the warmer ba in bright light, yet at dusk the vivid one starts to almost get better/sharper the later it gets.

They’re different on different days though, after a rain they both look incredible but again in bright light the vivid looks more washed out to me, almost like a slight haze to them. Probably just sample variation, or as you stated ones a rose and ones a lemon.

 

[casscade]

There’s a great thread here on lens coating, light spectrum/wavelengths, and contrast that I remember making a lot of sense, can’t remember it though.

 

[LarryO]

LarryO said:
There are actual transmission spectra for a Trinovid BN 10x42 and an Ultravid (non HD) 10x42 in post #4 of the thread 'Coatings Questions' <Coatings questions>... The spectra do display differences, and the post discusses ideas about which of those might affect perceived brightness, contrast, and overall color.
----------------
tenex said:
Not, however, depth of field. And you still have provided no putative reason how or why they would affect depth of field, leaving me quite comfortable concluding that (contrary to any impression created above) you know of none.
----------------

"Not, however, depth of field." Correct. My intent in drawing attention to those figures was to show that there have been observed, measurable differences of transmission spectra between related models of Leica binoculars. In particular, in that pair, the BN's spectrum displays a flatter distribution, albeit somewhat lower overall transmission, while the Ultravid's has a noticeable transmission 'hill' in the red region.

"And you still have provided no putative reason how or why they would affect depth of field, leaving me quite comfortable concluding that (contrary to any impression created above) you know of none."

Correct again. As I noted in an earlier post "I'm neither an ophthalmologist nor an optics expert,..." so was not able to produce from existing personal knowledge evidence-based reasons for the ideas proposed. I didn't intend to create an "impression" that I had the expertise to provide such evidence. However, the argument that I "[knew] of none" does not imply that there is none. My purpose in proposing some possible explanations for interesting visual differences reported by others was a likely naive hope that other birdforum members, with greater expertise, might discuss the ideas in a constructive way.

But it is not particularly difficult to find hard science supporting the idea that visual accommodation for distance is affected by the spectrum of illuminating light. It appears that accommodation might actually depend on the spectrum. Below is a link to one paper I found with ease. Perhaps it will provide some of the sorts of technical detail you've found wanting in my posts.

Accommodation with and without short-wavelength-sensitive cones and chromatic aberration
<Accommodation with and without short-wavelength-sensitive cones and chromatic aberration>

My thanks again to casscade and others who have reported their very interesting (to me) personal experiences of visual differences among various binoculars.

Larry

 

[tenex]

The eye, using a simple lens, suffers from longitudinal chromatic aberration, so its ability to accommodate for different distances in a view can depend on the distribution of colors in the light involved.

Suffers? There's good evidence now that the eye actually uses LoCA to first determine the necessary direction in which to adjust focus, much like the speed of phase-detect AF in cameras. And its ability to do that depends on spectral distribution only in the sense that an actual distribution (as opposed to monochromatic light) is required in order to detect differences in aberration. (This is evident in the paper you cited, apparently imagining that it supports your proposal.) It's just not plausible that slight variations in overall color cast of full-spectrum daylight would significantly affect this mechanism (nor is it obvious that such an effect would result in a spatial restriction of accommodation). From whom would this relatively simple observation need to come for you to be inclined to accept it? Why do you use phrases that sound like positive assertions when you admit to lacking the requisite knowledge? It would seem more natural under such circumstances to ask a question instead (and accept the answer).

My purpose in proposing some possible explanations for interesting visual differences reported by others was a likely naive hope that other birdforum members, with greater expertise, might discuss the ideas in a constructive way.

It is unfortunate that all one can do with a poorly founded proposal is refute it, and that this appears not to feel constructive to you. But I'll agree that there's some potential interest to understanding impressions or perceptions, and wait to see whether anything further might somehow come of it this time around. So many factors are involved in the use of binoculars that it's hard to be sure there's even a phenomenon here at all, or what it is; actual experiments might be necessary. Meanwhile, useful discussions of DOF (sadly lacking in speculation about lens coatings, but exploring some potential confusions) can be found in such threads as these:
Depth of field, depth of focus: relevant to binoculars? - Binoculars - Cloudy Nights
Depth of Field ? - Binoculars - Cloudy Nights

 

[LarryO]

LarryO said:
The eye, using a simple lens, suffers from longitudinal chromatic aberration, so its ability to accommodate for different distances in a view can depend on the distribution of colors in the light involved.
------------------
tenex said:

"Suffers? There's good evidence now that the eye actually uses LoCA to first determine the necessary direction in which to adjust focus, much like the speed of phase-detect AF in cameras. ...
(This is evident in the paper you cited, apparently imagining that it supports your proposal.)"
------------------

This was, indeed, an aspect of the paper that I had in mind when adding the phrase "It appears that accommodation might actually depend on the spectrum" without elaboration in my post. I didn't "imagine" that it supports my suggestion, only thought that it provided some evidence of the sort you seemed to want that accommodation for distance is affected by spectrum.

tenex said:

"It's just not plausible that slight variations in overall color cast of full-spectrum daylight would significantly affect this mechanism (nor is it obvious that such an effect would result in a spatial restriction of accommodation). From whom would this relatively simple observation need to come for you to be inclined to accept it? Why do you use phrases that sound like positive assertions when you admit to lacking the requisite knowledge? It would seem more natural under such circumstances to ask a question instead (and accept the answer)."
------------------

Well, the assertion that "it's just not plausible..." might have greater influence if it were supported by some evidence -- either spectral-transmission measurements of various binoculars accompanied by user reports of the perceived DOF seen with them or some hard-data measurements of perceived DOF for views illuminated by light of various spectral distributions.

I have actually tried to avoid appearing to make "positive assertions," given the frequently expressed limits of my own expertise. I have only been suggesting for discussion possible explanations for interesting reports by users of differences in perceived DOF among binoculars with different spectral transmissions, the latter suggested to result from coating differences.

tenex said:

"It is unfortunate that all one can do with a poorly founded proposal is refute it, and that this appears not to feel constructive to you."
------------------

As you might yourself note, a refutation without supporting evidence is just a type of 'assertion.' For me, constructive input would involve citation of some theoretical reason or experimental evidence that argues against a suggested (hypothetical) explanation for a reported phenomenon.

tenex said:

"But I'll agree that there's some potential interest to understanding impressions or perceptions, and wait to see whether anything further might somehow come of it this time around. So many factors are involved in the use of binoculars that it's hard to be sure there's even a phenomenon here at all, or what it is; actual experiments might be necessary. Meanwhile, useful discussions of DOF (sadly lacking in speculation about lens coatings, but exploring some potential confusions) can be found in such threads as these:
Depth of field, depth of focus: relevant to binoculars? - Binoculars - Cloudy Nights
Depth of Field ? - Binoculars - Cloudy Nights"
------------------

I am pleased that we do agree on the potential interest of the reports and on the need for something "further" about them! And thank you for the link to that Cloudy Nights discussion. Interestingly, it began (its post #2) with the understanding that, for binoculars, "The depth of field which an observer can attain is primarily determined by the accommodation capacity of his eyes,..." My take is that there might have been something worth discussion in my suggestion that accommodation, thus perceived DOF, could depend on transmission spectrum and thus on lens coatings.

In any case, I think it's (past) time for me to depart from this topic, hoping that others might be able to contribute more to it. I do thank you for your continued, albeit sometimes sharp, engagement in the conversation.

Larry

 

[casscade]

Got another question that pertains to the older Leica ba/bn series, I’m sure it can happen to any brand but I’m mainly referring to leica. What causes or can cause binocular prisms to get a hazy/milky view,..and can it be fixed/corrected?

Also how does one tell if a hazy view is even caused from the prisms, is there a way to actually check prisms.

Reason I ask is I’ve found a pristine 8x32bn but it seems to have a noticeable hazy-milky view. Another note, if under warranty would hazy prisms fall under manufacturing defects.

 

[NDhunter]

A hazy milky view means there has been some fogging inside, and that comes from moisture, etc. and that means it would need a good cleaning.
You can try to inspect better by using a bright flashlight looking into the objective lenses.
As far as wty. the original owner may be able to send it in for service, but with Leica that is no known unless you check.
It seems Leica is now doing better with their warranty service, and that is a great thing.

Jerry

 

[tenex]

Well, the assertion that "it's just not plausible..." might have greater influence if it were supported by some evidence...

No one is obliged to work very hard to disprove implausible hypotheses; the burden is on you to establish exactly what a purported phenomenon actually is ("experimental evidence"), and how a proposed explanation would work ("theoretical reason"). Which you haven't done, and have failed even to interest anyone in... because the idea is just absurd.

To possibly realize this yourself, consider that if the effect you're imagining could actually be produced by few-percent transmission variations due to coating differences, that would be completely swamped by the effect of far greater daily variations in spectrum due to weather and lighting. Everyone using a binocular would see such striking differences in "perceived DOF" under various conditions that even your collectors would be unlikely to develop an impression that one pair differed consistently from another.

 

[Ries]

Is my guess about right a 10x42 BN and pre-'15/'16 Meostar HD would perform about the same with regard to brightness and resolution/sharpness, though the latter would probably have a larger sweetspot, less CA on the edges and more field flatness?

 

[John M Robinson]

Andy:
I agree with you, the Leica Ba or Bn, does the job nicely. The 8x32 models are very good.
For those watching, your binocular search could be one and done with this binocular.

Jerry

I foolishly sold my 8x32 BNs about ten years ago. I also owned, still own 8x32 SEs and a 8x42 Ultravid, so didn’t feel the need to keep the BNs. What Andy said about fitting in the hand is so true, I just loved the ergonomics of them. They also possessed that signature Leica view. Very contrasty, with a colorful punch. Like Andy, I didn’t like the 42 size BN at all, it felt clunky to me.

 

[LarryO]

The recent contribution to this old thread reminded me of the exchange with tenex about my suggestion that the apparent DOF of different binoculars could arise from differences in eye accommodation based on differences in spectral transmission. (Tenex rejected in very strong terms even the conjecture of that possibility.)

But he did make one comment that invites a follow-up. He noted that light spectrum changes rather dramatically during the day. So a tentative experiment is suggested that needs only a single pair of binoculars: Does apparent DOF change with time of day, differing particularly between high noon and sunset (or even during the "blue hour" just before sunrise and just after sunset)? I would be very interested in comments on this from users.

Larry

 

[Binocollector]

From what I read (in Holger's bino book amongst other sources) I gathered (granted I understood things correctly) that what one sees as "Depth of Focus" through a bino is really only the amplified depth of focus of one's own eyes, since the eyes can be seen as a tiny camera in which DoF depends on aperture while a binocular itself is an afocal instrument that really has no DoF in itself. So (the other factor being magnification) the only way DoF might change is when your pupils get smaller because of brightness. And how large that effect might be or whether it is even noticable, I don't really know.
Others sure will know more about that.

 

[tenex]

So a tentative experiment is suggested that needs only a single pair of binoculars: Does apparent DOF change with time of day, differing particularly between high noon and sunset (or even during the "blue hour" just before sunrise and just after sunset)? I would be very interested in comments on this from users.

I applaud even tentative interest in evidence. Actual measurement would be best if anyone cares to make the effort, but if we must start with anecdote, negative and positive reports are in principle equally welcome. (I have noticed no such effect myself.) I suppose that besides directly noticing a difference in visual impression, one might also just find oneself fussing more with focusing in one hue of light than another, i.e. open sunlight vs overcast or shade? Twilight would be of particular interest but unfortunately such observations seem unlikely to be useful due to diminished visual acuity.

 

[Canip]

Does apparent DOF change with time of day, differing particularly between high noon and sunset (or even during the "blue hour" just before sunrise and just after sunset)?

I usually measure myself the AFOV (apparent field of view) of all my binoculars (see at The PINACOLLECTION – Binoculars Today) and can assure you that my measurements remain exactly the same between high noon and sunset (and also between sunrise and high noon).

Canip