10x32 LX vs. LXL (1 Viewer)

henry link · Jul 31, 2007

Well Ed, your "teaser" has certainly piqued my interest. I'll be interested to learn how you made these measurements and just what "weighted day and night vision transmission averages" means.

The few lab measurements of light transmission I've seen fall into two categories: those that measure the transmission across the entire visual spectrum and present the data as a curved line on a graph and those that present measurements for two wavelengths only, one corresponding to the peak sensitivity for scotopic vision (510nm, so called "night transmission ") and the other corresponding to the peak for photopic vision (555nm, so called "day" transmission). A "weighted average" for night and day would seem to be yet another way to simplify the data and couldn't be compared directly to 510 and 555nm peak measurements.

FWIW I find graphs are much more informative. The shape of the curve explains a great deal about what we see as brightness, contrast and color cast. For instance, Nikon/Fujinon and some others show maximum transmission between 600 and 650nm which explains why their color cast appears slightly red. A binocular with a peak between 570 and 590 will show a yellow cast. Combine a transmission peak that's close to the eye's maximum photopic sensitivity with rapidly falling transmission between 500 and 450nm and you have a binocular that acts as a mild blue rejection filter and will look impressively high contrast in sunlight.

Henry

elkcub · Jul 31, 2007

Henry,

The analyses were done by an acquaintance of ours in Germany, but the language is somewhat of an impasse for me until Renze returns. I used the phrase "weighted average" to cover all the bases from a selected datum to a more complex function. (I'm slippery that way.

)

We have full spectrum data for the left and right sides from 380-780 nm, including a data plot and specific values for each 5 nm range. The attached file summarizes the numbers I mentioned earlier (right side only), as well as specific values for 510 and 555, which are somewhat different. That's what led me to assume weighted averages.

In each distribution, the range from 580-680 is quite flat and contains the max value at the frequency shown. Below 580 nm a significantly lower plateau is reached in each case, so the distributions are basically bimodal. I've seen other plots, however, which are much more multimodal. Conversely, the Leica 7x42 is remarkably unimodal with a gradual peak of 89.08 at 625 nm. Of course, whatever the transmission distribution shape is, the perceived effect must be factored with the sensitivity distribution the individual's rod/cone transducers.

I'm sure we'll be seeking your assistance to interpret the data we are able to publish.

Ed

henry link · Aug 1, 2007

Ed,

Thanks for that information. This project could be a very valuable addition to our knowledge of light transmission in binoculars. I hope you will be able to give us some details about the techniques and equipment used. The transmission of the HHS is really quite low for a modern binocular. Perhaps aluminum mirror coating is being used on the prism? If not, it's hard to understand where all the light is going.

I'm looking forward to seeing more of your results. Complete plots would be nice. ;-)

Henry

elkcub · Aug 1, 2007

henry link said:
Ed,

Thanks for that information. This project could be a very valuable addition to our knowledge of light transmission in binoculars. I hope you will be able to give us some details about the techniques and equipment used. The transmission of the HHS is really quite low for a modern binocular. Perhaps aluminum mirror coating is being used on the prism? If not, it's hard to understand where all the light is going.

I'm looking forward to seeing more of your results. Complete plots would be nice. ;-)

Henry

Henry,

I had the same reaction about the HHS, but it's possible it was the first model and not the current one. That will be checked out very carefully, since I'm sure it's a big disappointment for those who own them. I'm thinking of pulling the chart until that's fully clarified. I've had those data for about 9 mos.

Charts would be most useful and we'll provide them in the final venue.

Thanks,
Ed

ceasar · Aug 1, 2007

Ed and Henry,
You guys have out run me on this. I'll have to run it my my son who is a Physics and Math Major at the U. of Scranton. He has taken Optics among other courses. My brief comparison of the HHS and the EL wasn't under ideal conditions. I was at the Hawk Mountain Store in Pennsylvania and I was looking out through a couple of windows at birds and squirrels on bird feeders and in the near surrounding area. It was about noon on a bright day but there were also shadowed areas in the view. Under these circumstances the HHS performed very well when I compared it with the EL. I expected the EL to be much better and was rather surprised that it wasn't. Once again, I note that this was a very subjective and brief comparison but it was enough to convince me that the HHS is a very good (I might add, excellent) binocular, especially at it's price.
Cordially,
Bob

Surveyor · Aug 1, 2007

Ed, Henry;

I am really looking forward to your discussion of this. In the past I have seen figures for close to the same bins, ones I have directly compared and saw a test result indicating around 80% and a different source indicating 91%+. I was able to track the lower figures back to a specified bandwidth of 400-700 nm bandwidth for the final report, but have never seen any other bandwidths listed. I wonder if anyone has seen the ISO or NSIT standards and if there is a bandwidth specified. I imagine you could get considerably higher using only 100 nm centered on the peak frequency, but that would really make comparison tough.

Looking forward to Ed's data and the following analysis.

Ron

elkcub · Aug 1, 2007

All,

I decided to put my brief summary data back in post #22 for the 828 HHS and 820 Audubon after going over all of my data files. Everything seems to be in order, but unfortunately this particular HHS just didn't do very well. The left and right tubes produced almost identical spectra, as did the other sample binoculars.

Henry, I don't have any idea where the light went. That's why we have you to tell us. I'll look for a hole somewhere. :eek!:

Ed

hinnark · Aug 1, 2007

Measurements of light transmission in binoculars

Ed and Henry,

I found recently a very interesting statement by EdZ of CloudyNights about vignetting in binoculars:
http://www.cloudynights.com/ubbthre...1665868/page/0/view/collapsed/sb/5/o/all/vc/1

If my understanding of this is correct that could mean that measurements of light transmission needs to be modified. A measurement in the center of the optics may produce other results than one at the edge. I have never seen any report about light transmission that considers vignetting. Anyway if it´s true that vignetting plays a role I can only assume that there´s an effect on the optical performance of binoculars in low light I have never heart before. But this could explain some findings I made by comparing several binoculars in low light.

Steve

P.S. Ed: If you need some German translation support, there´s no problem.

elkcub · Aug 1, 2007

ceasar said:
Ed and Henry,
You guys have out run me on this. I'll have to run it my my son who is a Physics and Math Major at the U. of Scranton. He has taken Optics among other courses. My brief comparison of the HHS and the EL wasn't under ideal conditions. I was at the Hawk Mountain Store in Pennsylvania and I was looking out through a couple of windows at birds and squirrels on bird feeders and in the near surrounding area. It was about noon on a bright day but there were also shadowed areas in the view. Under these circumstances the HHS performed very well when I compared it with the EL. I expected the EL to be much better and was rather surprised that it wasn't. Once again, I note that this was a very subjective and brief comparison but it was enough to convince me that the HHS is a very good (I might add, excellent) binocular, especially at it's price.
Cordially,
Bob

Bob,

You know, even though we'll be presenting some transmission data on a few models, I continue to believe that perceptual experience should rule. In this case the sample HHS used for testing showed up relatively poorly. Assuming it's a representative sample from the population of HHSs, and the results are accurate, what does it mean? I'm not sure it explains why my HHS seems a bit darker than the LX L (for which I have no data), although it does say that one can get a damned good view from a lower transmission optic.

Without jumping to conclusions, I think the darker perception may have more to do with the transmission distribution (as Henry's comments suggest) and how that interacts with the retinal sensitivity curve, than the absolute levels. Let's say, for example, there were a 10% transmission difference across the spectrum. In sunlight that could be compensated for by the pupil expanding a small amount, which doesn't compromise acuity (but could effect DOF somewhat). The HHS's larger EP of 5.12 mm allows for a lot of this brightness compensation, but it can't do a thing about the shape of the distribution itself.

Anyway, I wouldn't give up on the HHS for this reason. I still use mine and like it, and recommend it. It's an easy view, a fine piece of equipment, and a good buy for the money.

Ed

elkcub · Aug 1, 2007

hinnark said:
Ed and Henry,

I found recently a very interesting statement by EdZ of CloudyNights about vignetting in binoculars:
http://www.cloudynights.com/ubbthre...1665868/page/0/view/collapsed/sb/5/o/all/vc/1

If my understanding of this is correct that could mean that measurements of light transmission needs to be modified. A measurement in the center of the optics may produce other results than one at the edge. I have never seen any report about light transmission that considers vignetting. Anyway if it´s true that vignetting plays a role I can only assume that there´s an effect on the optical performance of binoculars in low light I have never heart before. But this could explain some findings I made by comparing several binoculars in low light.

P.S. Ed: If you need some German translation support, there´s no problem.

Steve,

EdZ's thoughts are always interesting, although my personal limit for stringing assumptions together is about three. After that, my brain freezes solid. ;-D) He didn't seem to bring up the distribution issue, which is important for perceived brightness. You know, 100% transmission of a wavelength the eye isn't sensitive to produces 100% blackness, etc. He also didn't bring up the Styles-Crawford Effect of the First Kind; namely that luminous efficiency is a function of the angle at which light strikes the retina.

In this instance, fortunately, the standard white light presented to the objectives was 16 mm in diameter and delivered on-axis. Off-axis might have produced different results. Optical vignetting within the design, I guess, becomes part of the input-output relationship, ... but it could be a candidate for where some of the light goes, right Henry?

Ed

henry link · Aug 1, 2007

Yes, I think a 16mm beam could begin to bring the effects of vignetting into the measurements of some binoculars. I don't think the debate about vignetting at CN has been completely resolved. It's a difficult subject.

Some of the light transmission tests I've seen have used very narrow beams. As I remember 2mm, 1mm and in one case a green laser. Any binocular should be vignette free within the center 2mm of its objective. A 16mm beam, on the other hand, might tend to favor binoculars with large objectives, large prisms and/or a combination of narrow fields and/or small exit pupils because those would be the least likely to show any vignetting within the center 16mm of the objective. A very narrow beam allows us to be certan that the transmission losses being measured are entirely from reflection, scatter and absorption. It makes sense to me to first measure transmission as if there were no vignette. Then whatever additional light losses come from vignetting at various beam widths up to the full objective size could be measured in a separate test. Otherwise it will be impossible to tell from the raw measurements how much of the loss in a particular binocular is a transmission loss and how much comes from vignetting.

elkcub · Aug 2, 2007

Yes, I certainly agree that differential vignetting influences the results, and the output data include whatever is inherent in each instrument, as I stated above. This circumstance mimics what is experienced in daily use, which is probably what most people are interested in. It really doesn't matter what the source of light loss is, since that's the manufacturer's job to diagnose and correct. Hence, analyses such as these primarily have merit for the user.

Although I hadn't given it much thought, 16 mm seems to be a practical setting for 8.5x44 Audubon comparisons, since it corresponds to a 1.88 mm exit pupil — which is about the smallest the eye can contract under very bright conditions. Because the exit pupil determines the amount of light entering the eye, it might be that standardizing on such a fixed exit pupil size is what's needed for making meaningful cross-configuration comparisons. Perhaps that's why the testing apparatus has an aperture diaphragm. What I'm thinking would also require that the apparatus be capable of controlling total light energy over this variable aperture, which it probably can.

Anyhow, my primary interest would be in knowing the typical light distribution that is presented to the user's eye rather than diagnosing why it is that way. Of course, interests do differ. ;-)

Then again, we don't have much to say about how the data are collected anyway; ours is just to receive them and be grateful — which we are.

elkcub · Aug 2, 2007

hinnark said:
Ed and Henry,

I found recently a very interesting statement by EdZ of CloudyNights about vignetting in binoculars:
http://www.cloudynights.com/ubbthre...1665868/page/0/view/collapsed/sb/5/o/all/vc/1

If my understanding of this is correct that could mean that measurements of light transmission needs to be modified. A measurement in the center of the optics may produce other results than one at the edge. I have never seen any report about light transmission that considers vignetting. Anyway if it´s true that vignetting plays a role I can only assume that there´s an effect on the optical performance of binoculars in low light I have never heart before. But this could explain some findings I made by comparing several binoculars in low light.

Steve

P.S. Ed: If you need some German translation support, there´s no problem.

Steve,

I could use some help with translation. What do these phrases mean?:
"Kolli.-Brennweite in mm:"
"Ø-Falschlichtblende in mm:"

Incidentally, EdZ's discussion mentions that:

... Most vignette studies show that approximately the central 50% of an objective lens provides 100% illumination of the exit pupil. The light delivered from the area outside the central 50% of the objective does not all reach the exit pupil...

I have no reason at all to doubt what he said, and would note that the 16 mm aperture used in our tests is less than 50% of the 44 mm objective diameter. If EdZ meant area and not radius, then the test zone is only 13% of a 44 mm objective's. So, a 16 mm test diameter should be safe for at least a 32 mm objective, and such a test area safe for a 25 mm objective with room to spare.

I mentioned that the current tests were done on-axis, but I think your point is valid about off-axis effects. However, with all the complications associated with kidney beans, blackouts, cross-angle geometry, etc. I'd venture it would be a major enterprise to develop an effective universal protocol that meant anything. The optics boys (and girls) spend almost no time discussing eye rotation effects because the centering status and geometry are so complicated. The modeling would be in differential equations, for sure.

Ed

hinnark · Aug 3, 2007

elkcub said:
I could use some help with translation. What do these phrases mean?:
"Kolli.-Brennweite in mm:"

That means: focal length of the collimator. Obviously they use a collimator as part of the test set-up.

"Ø-Falschlichtblende in mm:"

Ø means diameter. Falschlicht means stray light or scatter and so I would suggest this translation: "diameter or aperture size of the baffle for stray light prevention" but I´m not sure which particular baffle is meant here. Maybe it´s the field stop (German: Feldblende) meant here?

Steve

hinnark · Aug 3, 2007

elkcub said:
I mentioned that the current tests were done on-axis, but I think your point is valid about off-axis effects. However, with all the complications associated with kidney beans, blackouts, cross-angle geometry, etc. I'd venture it would be a major enterprise to develop an effective universal protocol that meant anything. The optics boys (and girls) spend almost no time discussing eye rotation effects because the centering status and geometry are so complicated. The modeling would be in differential equations, for sure.

Ed

Ed,

I think we could initially exclude kidney beans, blackouts, cross-angle geometry, etc. if we think about the night time use of a binocular when our eye pupils are wide enough to get all the light from 42 or 50mm binoculars. Maybe it´s possible that binoculars with a lower on-axis light transmission but no vignetting can perform better in low light than one of the highest on axis performance with vignetting? If so maybe all the advertising refering to light transmission could be questionable. I think that was EdZ and Roland Christen thought about when refering to "high class birding optics".

Steve

henry link · Aug 3, 2007

Ed and Steve,

I don't want to get too far into the subject of vignetting in binoculars because it makes my head hurt. I think if you read ALL of the contentious threads at CN on the subject (be sure to carefully peruse all the ray trace diagrams) your head will hurt too.

I don't think there is good consensus about the effect of prism housing vignetting on the exit pupil, but there is better agreement that the prism housing in all binoculars vignettes the IMAGE PUPIL to some varying extent. In this case the image pupil is the aerial image that forms inside the binocular at the focal plane of the objective and is limited by the fieldstop of the eyepiece. Vignetting of the image pupil has a distinctly different result from vignetting of the exit pupil. A vignetted exit pupil (like the squared off shadowing you see at the edge of the exit pupil from BK7 glass) dims the image evenly across the FOV, but a vignetted image pupil results in uneven illumination across the FOV. Some area in the center of the field will be vignette free and as bright as the transmission of the optics allows but the image will very gradually darken toward the edge (so gradually that the fall off in brightness is not very noticeable). So, a binocular with a vignetted image pupil, but very high transmission optics, will almost certainly look brighter toward the field center, where we tend to make brightness judgements, compared to a binocular with lower transmission optics but less vignette of the image pupil.

Henry

elkcub · Aug 4, 2007

Steve: Many thanks for the translation, something I would not be able to do with all the translators on the Internet. It's all making more sense, and, fortunately, consistent with my assumptions about the apparatus.

I can't find the "high class birding optics" reference you mentioned. Although CN astronomy discussions are fun to follow, sometimes, I tend to avoid them because day and night vision (i.e., photopic vs. scotopic) tasks are as different as ... okay, day n' night. Not to pontificate, but the eye is an amazingly different sensor when dark adapted, not only in raw sensitivity to light, which is several orders of magnitude greater, but also the larger area of the dominant sensor array (rods) and its location. It's like switching from from a Formula-1 race car to a bus. Mercedes may make both, but ... they're really not optimized for similar tasks.

Henry: I follow what you're saying and find it insightful, but I don't get what you're suggesting in terms of the aggregate transmission data we have available. I agree they will not be very useful for decomposing whatever vignetting is present, but my belief is that vignetting is minimal below 50% of the exit pupil area anyway. Frankly, I'm much more excited about the frequency distribution, which interacts with the cone sensitivity functions to determine color perception.

Blue skies,
Ed

Patriot222 · Aug 19, 2007

I just came home from from the store where one of my local optics dealer was selling the LXL for $699 plus tax. He was down to the last pair and I knew this was a good price but I didn't "pull the trigger" yet.

I've been looking for a friendly 8x32 for my GF and seem a bit stuck into a roof prism because of it's handy and comfortable size. The other problem that I've run into is that she's been looking through my swarovskis, zeiss and leica glass over the past couple years and notices the difference now when viewing through lesser optics. I guess you could say she's been spoiled..lol.

I just wanted to ask some of you Nikon pros what you think of the 8x32 LXL. I can buy new, old stock swarovskis 8x30 SLC for about $75 bucks more than the LXL and I already know that she likes those and they're comfortable for her. I guess that I was a little bit surprised when hearing about how the LXL comes with a cheepie strap, ocular cover, acessories and was more surprised to hear how the LXL wasn't as sharp as the LXs. I only spent about 5 minutes in the store with them and they were very bright but I didn't compare them head to head with a new SLC. I wanted to ask if anyone here has compared the SLC to LXL. I have 8x30 SLCs now and am very happy with them although I do prefer a rear focus knob. Your thoughts......

Thanks |=)|

elkcub · Aug 19, 2007

I've owned 8x30 SLCs for 15 years, and they are great! The new ones have improved coatings and can be used with glasses. But, it is an old design. The near focus is not up to today's standards, and the eye relief is inadequate when using glasses. I find they are always on the edge of blackouts.

The 8x32 LX L weighs 2-3 oz more than the SLC, and the accessories are a joke. Lateral CA is slightly greater in extreme contrast conditions, but still well controlled and not problematic for me.

But it's built as well, IMO, and has the following features you'll probably enjoy:

# Very bright clear image, with excellent sharpness and color contrast.
# Flat field similar to Nikon SE.
# Excellent four-position eyecups and no hint of blackouts.
# Full field vision with glasses.
# Locking right diopter adjustment control.
# Diopter scale beneath the hinge.
# Left rotation as per SLC.
# Very quick and fluid focuser, located at the back where you want it.
# Outstanding grip ergonomics, which allows true focusing with one hand.

Eagle Optics sells tethered objective covers that work great for $7, and I found that old Swift Audubon rainguard fits perfectly. Others can also be found, I'm sure.

I made the same choice and have absolutely no regrets going with the LX L. And I also got the same price — $699. You might get jealous of your GF.

Blue skies,
Ed

Patriot222 · Aug 20, 2007

Thanks for the opinion elkcub. You've convinced me to go with the LX L. Even though they're a few ounces heavier than the SLC 8x30, they're still lighter than 42s and that's what she has been using. I really do prefer the rear focus too.

Since we live about 70 miles apart, I think you're right...I will be jealous because they'll truely be hers. She'll be able to enjoy birds, butterflies, and other critters right from her front porch. At least I'll get to use them on the weekends with her |=)|

10x32 LX vs. LXL (1 Viewer)

Well-known member

Silicon Valley, California

Attachments

Well-known member

Silicon Valley, California

Well-known member

The more I understand, the more I understand why I

Silicon Valley, California

Well-known member

Silicon Valley, California

Silicon Valley, California

Well-known member

Silicon Valley, California

Silicon Valley, California

Well-known member

Well-known member

Well-known member

Silicon Valley, California

Well-known member

Silicon Valley, California

Well-known member

Similar threads

Users who are viewing this thread