Colour distortion and supernatural views? (1 Viewer)

Apologies for some rather geeky questions that have been bugging me for a while. Do some binocular designs deliberately incorporate chromatic and other distortions to enhance the performance for certain applications? If so how do they do it?

I'm no expert here, but occasionally I pick up a pair of bins that stand out as having 'super-natural' quality. An enhanced contrast, vivid colours, and a sculptural quality to the subject in view. Definitely a wow factor. Appealing to me for sure, but at least in mid range bins, I've noted these can go hand in hand with negative features as well. One pair that springs to mind is the Zeiss Conquest 10x30. For the rendition of surface textures, and vibrancy of primary colours, I've yet to see better. But, for me it has the worst colour fringing I've seen, poor detail in greys and muddy colours and a surprising amount of edge distortion (if I remember correctly)..... Are these designed for horse racing for example? Compare and contrast the old Nikon Monarchs. I would suggest technically more accurate by most measurements, but for me, a rather dull view.... Would these be for hunting?

I have no physics training, but I do have a little understanding of coating technologies and the optical materials that might be employed. It's technically extremely challenging (impossible?) to design to design coatings that reflect, interfere and refract uniformly across the full visible spectrum (and it might not be desirable in practice). Do manufacturers instead use more selective wavelength manipulation and deliberate chromatic distortions to enhance the performance for certain applications? I suspect the answer is yes. A most obvious example. Military spec. binoculars with their 'yellow' tint seem to sacrifice natural colour rendition for enhanced contrast at dawn/dusk. The differences in consumer products are certainly more subtle, but personal preferences in spectrum distortions could easily account for some of the passionate debates we see on this forum.

This would mean that astronomical, nautical, sports, hunting and 'nature' etc. binoculars might have very different resolution, contrast and transmission performances at different wavelengths. Does anyone have any knowledge of this or done any monochromatic testing? If so what are the design characteristics that are optimal for birding and wildlife? Or, more contentiously, is technical optical 'perfection' actually desirable for 'real' applications?

Of course this could all be b*****ks. I've just picked up on accidental random design deficiencies, and tried to assign some intelligent intent.

Regards,

David

Oops! Not sure how I managed to post this in the Zeiss forum. It was intended for the general one. However I suspect most of the experts post here.

David

Hi David;
The link below may help with some of your questions. Hope it helps.

Optical coating technology By Philip Baumeister

http://books.google.com/books?id=3T...&resnum=9&ved=0CDoQ6AEwCA#v=onepage&q&f=false

David,
Those are good questions, and I think this area is some of the deep water of the viewing experience. That is, I don't know, and I don't think anyone who does know, can tell, without losing their job at Zeiss, etc.

All I can do is contribute a few random and not extremely well founded factoids.

Here are some samples of what can be done with multilayer antireflection coatings.
http://www.evaporatedcoatings.com/glass-substrates.htm
After looking at all these possibilities, I am left thinking that the manufacturers have the capability to make the shape of the color transmission curve pretty much any way they want it. It's a "simple" matter of tailoring the layer thickness of the coating compounds to the substrate type. Codes to calculate this are easy to run and highly refined, and the machinery is at such a level of precision that the intent can be well implemented, and as such, would be no more difficult nor expensive in principle to get one result, than another. Decide on the desired result, run the code to design the coating, program the coating machine to apply the coating.

I have see a lot of binocular color transmission plots, none flat over the visible. Most are weighted towards the longer wavelengths more or less. People tend to be forgiving of or actually prefer slightly red, brown, and yellow toned images, calling them warm and comfortable, but often dislike blue casts, calling them cold and harsh. But however you weight a transmission curve, it will have a different impression, and strengths, and weaknesses.

The Zeiss FLs are noted for low light performance, and their color transmission is skewed more to the shorter wavelengths than most binoculars. Some claim it is merely accurate rather than golden-toned, a few complain of blueness. This is supported by the strong deep red reflections off FL coatings, and some transmission plots I have seen and heard described which are weighted more in the center than most, in the green. Dusk light is bluer, being more predominantly from Rayleigh scattering in the famously blue sky and less from direct white light from the sun, and additionally, the eye becomes more sensitive to shorter wavelengths as illumination diminishes. So I would guess, Zeiss did what they intended, and got that one right, but of course not everybody loves it.Zeiss ads attribute the low light performance to the FL glass, which doesn't make a lick of sense to me, suggesting that, big surprise, they are fibbing in a typical advertising misinformation manner, in order to sell expensive binoculars.

Leica fans often admit to seeing a golden bias, and to loving its warm rich look, and the Leica transmission curves I have seen, are consistent with this. I have read in Leica product literature that it would have been easy for them at any time to obtain a brighter image, but only by introducing undesirable weight into the blue, and for that reason, improvements in brightness have been tempered by the need for keeping the color balance as is. Again, I would say that Leica has done what they intended to keep the trademark "Leica View".

I have read that some binoculars marketed at big game hunters do especially well at heightening the contrast between hair brown and leaf green. I don't know--seems like deer type season is in cold weather when everything is mostly brown, but what do I know? There's always green pine trees, but the greenery is way up in the air!

So I would say these things are not accidents, and that we consumers should feel honored to be the objects of so much mysterious optical magic. Fortunately, I personally am not very sensitive to slight amounts of color skewing!
Ron

Thanks Ron and Ron for the links.

I have occasionally used interference filters and dichroic mirrors etc. It's good to know a little more about how they are constructed, but I'll keep the finer points of the maths for those bouts of insomnia.

The differences I see between different models are on occasion are pretty dramatic. I guess they are intended to meet specific expectations for use or user. It would be nice to understand what it is.

Like you say RonH, it's difficult to see that the various characteristics can be accounted for by the transmission curves and choice of glass alone, and I guess there is more to the phase shifting and dielectric coatings than they are prepared to say. As far as I can make out, resolution and star tests give little or no indication of the performance in this regard but I'm struggling to figure out what a useful test might look like... On the other hand if I did have red green and blue laser sources and an optical bench there might be fun to have a go?

David

Yes, excellent info on coatings, Ronh. I will peruse the e-book that RonE posted a link to on the weekend when I have more time.

But I did want to address another issue. David, you mentioned that the Conquest showed "a surprising amount of edge distortion (if I remember correctly)."

I'm not sure if Zeiss follows the same design plan with the Conquest as it does with the FL, but if so, the fuzzy edges are a trade-off for the ultra-sharp on-axis resolution.

Zeiss designed their FL by optimizing the sharpness of the image in the central portion of the field where most birders are going to place their targets.

Stephen Ingraham (the original reviewer on Better View Desired), who now works for Zeiss, explained this on his now defunct birding forum, z-birding (I hope that site gets archived).

Nikon follows a different design philosophy with its premium bins, stretching the sharp area nearly to the edges.

Personally, I find really fuzzy edges distracting, particularly while panning when my eyes tend to dart ahead into the "zone of unknowingness".

So I'm willing to give up a little on-axis performance for a more gradual fall off at the edges. But at least with the Nikons I've owned or tried - WF, E, EII, SE, LX, LXL, and EDG - the central sharpness seems quite good so I don't feel like I'm missing out.

Ditto to ronh's post.

Brock,

It's a myth that edge corrections require a trade off with center sharpness. Maybe Stephen Ingraham was given that information for the relatively simple eyepiece Zeiss uses in the FL's, but a designer doesn't have to use such a simple eyepiece. Swarovski SV, Canon L, Nikon SE and EDG use more complex designs which allow more freedom for corrections. The only trade off from extra complexity is slightly reduced light transmission.

Henry

Henry,
Of course you would agree with my post, I learned it all from you!

But I'm not so sure it will be easy for Zeiss to match Swarvision's edge sharpness in the next version after the FL. I say this because the light folding power of Zeiss's Abbe-Koenig prisms is so much less than that of the common Schmidt-Pechans. I have found diagrams of the rays through these prism types, and traced out the internal path, and pretty much can confirm other people's statements that the internal path/external length ratio for AK is about 1.3, vs nearly 2 for the SP. And prisms take up a lot of the space in a binocular.

This means that for an equal size binocular, the AK will always have a faster objective. I seem to recall estimates here of about f/3.3 for the FL vs f/3.8-4.0 for other brands. f/3.3 is going to be real mean on eyepieces--even a Nagler type with a built in Smyth lens can't handle that without edge blur.

So, why should Zeiss stick with AKs at all? The name? After all Abbe was a first rate optical genius, IMHO, and Zeiss's guiding light for years. But who ever heard of him, or Koenig, except the 0.01% of the market that is optics nerds? Even the history argument fizzles when you learn that Hensoldt, some 50 years before Zeiss acquired it, got the first patent to use AK prisms in a binocular.

AKs made a lot of sense when the best reflective coating on SPs was silver, and as a result the Zeiss Classics were the instant guaranteed brightest roof made, 9% brighter with no added color from the coating, right off the top, because they were completely internally reflecting. Plus, they bit the bullet and made them looooong. Now with dielectric coatings on the SP, the AK may still be 2% brighter, but that is not worth the penalty in edge sharpness when going after the high end market.

Maybe they'll make the FL2 open bridge while they're at it. Uh-oh, I overdid it, and now am starting to long for the days when a BMW didn't look like a Toyota. Give me a flawed binocular but one that has some character to it!
Ron

I'm slightly ashamed to say that I have mostly restisted testing the premier models... in the hope of avoiding temptation (we'll have to see how long that lasts!).

I chose to mention the Conquest and Monarch as they represent two very different approaches to optic design. I wasn't convinced that the Zeiss actually showed more resolution than the Nikon. However for me it created the impression that it does though an enhanced contrast and vibrant colours. I like what it does a lot, and personally don't mind the softer edges. The colour fringing is another matter. Perhaps that's the flip side of the dynamic presentation. The Nikon apppears equally detailed, but a more natural, less dynamic presentation. I certainly wouldn't argue which is superior. Obviously which is preferable is a matter of taste, but I would also suppose they are also designed for particular market segments and uses. I would guess the Conquest would be fantastic at picking out jockey's colours but don't know if that was the intention.

I'm curious how they achieve these differences. On a digital image, it's straightforward to tweak colour and contrast. On a microscope the manipulation of polarisation and phase to enhance the view is well understood. But how do they do it with binoculars? As far as I'm aware daylight isn't polarised or coherent. So do they do something pretty fancy with the coatings, or something else? I'd love to know what?

As a side issue to that, having found I have a preference, I would imagine most others would as well. However "dynamic" descriptors don't seem to appear in reviews etc. Don't think it's something you could easily measure, and I can't think of a terminology that would workin reviews either.

Hypo-, iso- and hyper-natural?
Infra-, supra-dynamic?

....Can't see these finding their way into a sales brochures.

David

typo said:

I'm slightly ashamed to say that I have mostly restisted testing the premier models... in the hope of avoiding temptation (we'll have to see how long that lasts!).

I chose to mention the Conquest and Monarch as they represent two very different approaches to optic design. I wasn't convinced that the Zeiss actually showed more resolution than the Nikon. However for me it created the impression that it does though an enhanced contrast and vibrant colours. I like what it does a lot, and personally don't mind the softer edges. ...

David

Click to expand...

David,

The Conquest and Monarch also represent two different price points in bins so you are not comparing apples to apples. A better match for the 10x30 Conquest, in terms of color saturation and contrast, build quality, and price, would be the Nikon 10x32 LXL.

http://www.amazon.com/Nikon-Premier-10x32-Binoculars-Wide-Angle/dp/B0002VAI04

You'll find at least as vivid colors, maybe better, but unfortunately there's also chromatic aberration, though I'm not sure if it's as bad as you describe the 10x30 Conquest.

But what you'll get with the LX/LX L is sharp horizontal edges (not quite as good in the vertical). It originally sounded like the "surprising amount of edge distortion" was a turn-off for you, but it appears it's not.

You will also get a significantly wider view with the Nikon (6.5* vs. 5.5* for the Conquest). For me, if a bin has only a 55* AFOV, it better have good edges. I wouldn't like the Conquest, because of its moderate FOV and fuzzy edges.

Not sure I would like the Nikon either since the 8x32 has a rather compressed image (that is, a lack of 3-D Effect) so I'm sure the 10x32 would be even worse in that regard. But if that issue doesn't bother you in the Conquest, it probably won't bother you in the Nikon.

The LXL also has a better close focus (listed at 8' but probably better, the 8x32 lists the same figure, but focuses down to 6.5').

Where the Conquest excels is its significantly lower weight (15.8 oz. vs. LXL's 24.5 oz.). Personally, I couldn't hold a 16 oz. 10x bin steady, I need more weight to dampen the vibrations even at 8x.

The best choice in a quality bin in this configuration appears to be the Nikon 10x32 EDG, which can be had until the end of the month for only $200 more than the Conquest.

You get ED glass to reduce the CA, and an open bridge design, which makes the bin easier to hold steady.

And if that were not enough, they are throwing in a FREE Nikon D3000 digital camera!

http://www.bhphotovideo.com/c/product/545987-REG/Nikon_7564_EDG_10x32_Binocular.html

The camera is worth around $500, so if you sold it, your final purchase price would be less than a 10x30 Conquest.

Crazy Eddie must be behind this deal!

I had a thread on coatings going last year. Here are some pictures of my bins and the color of the coatings.

The thread is here. http://www.birdforum.net/showthread.php?t=143478

I'm of the opinion that you can partially determine the color bias by seeing what color the binoculars coatings reflect back at you. These days that's more problematic in that on my Zeiss 10x42's for example it seemed every single lens surface had a different color coating. There was everything from a pinkish ruby to a yellowish color. Interestingly enough the coatings seemed much ligher in color than my conquest 8x30's that have a deep red wine looking ruby sort of color. ( Not the cheap "ruby" coatings you see in low end bins, more maroon like red wine) The conquests with the deep red coating had less light transmission, were colder yet had better color saturation. The FL was brighter, not as cold and didn't have the richness of color that the Zeiss 8x30 had. Made perfect sense to me.

BTW the general consensus around here on the Conquests is that the 8x and the 12x are the good ones and the 10x and the 15x are a bit dim in comparison and less preferred in general. Having both an 8x and a 12x Conquest I agree with this. (My poor little 8x now has a barrel stuck)||

( Edit) my thread is too old to reply to, I wish I'd known that before typing three paragraphs reevaluating my opinion of the Pentax 12.5x50.

HI Nessus,

An interesting theory. My very modest collection, seems broadly in line with your observations on colour at least. The first pair has relatively complex pattern, with very deep ruby red dominating and subdued blue/green and red highlights, has the best colour contrast. They have a 'lift' in the yellow, red and purple. The second has green/blue with some magenta fringing, had relatively poor colour contrast, a cooler view with yellows relatively subdued. The third has a simple purple coating. Again poorer contrast, but a warmer balance. My reccolection of the Monarchs and Conquests, tie in with your observations.

Thanks,

David