SF, NL: wide-field binoculars... why now? (2 Viewers)

[tenex]

The Zeiss SF and Swarovski NL have lately set new standards for a wide and sharp field of view in practical binoculars -- meaning excluding the Nikon WX, which has exactly the unwieldy soup-can eyepieces that previous discussions of this subject had featured as discouragement. Both products with their more modest designs have been very successful.

Is there a relevant technical advance, and why didn't it happen years ago? (this is what I'm most curious about...)

...or were demand and cost the only issues, and someone just had to make the investment and find out whether enough customers would pay the price? (and yet it seems that both were suddenly in development at about the same time?)

 

[Maljunulo]

New optical glass types, and advances in computer-aided optical design are my two best guesses.

 

[[email protected]]

Somebody from Swarovski or Zeiss could answer that question. An insider would have the best, most accurate answer to that question. It is a good question, though, and one I have often wondered about. Perhaps I will ask Swarovski and Zeiss.

 

[BKoh]

The Zeiss SF and Swarovski NL eyepieces are a compromise between long eye relief and a truly "wide" field, at least by telescope standards. So they are compact enough for handheld binoculars. The Nikon WX eyepieces are designed for ultrawide views and sacrifice compactness and some eye relief.

Telescope eyepieces show the compromises required. Televue Naglers are compact and offer ultrawide fields of view (82°) but have limited eye relief. Other attempts to improve eye relief in ultrawides have resulted in increases in size which make binocular use impractical due to weight and IPD.

Apart from a "new compromise" due to market demand (perhaps an ageing yet affluent customer base) another factor could be improvements in coatings, allowing complex multi-element designs that would previously have been disqualified due to excessive transmission losses.

 

[[email protected]]

The Zeiss SF and Swarovski NL eyepieces are a compromise between long eye relief and a truly "wide" field, at least by telescope standards. So they are compact enough for handheld binoculars. The Nikon WX eyepieces are designed for ultrawide views and sacrifice compactness and some eye relief.

Telescope eyepieces show the compromises required. Televue Naglers are compact and offer ultrawide fields of view (82°) but have limited eye relief. Other attempts to improve eye relief in ultrawides have resulted in increases in size which make binocular use impractical due to weight and IPD.

Apart from a "new compromise" due to market demand (perhaps an ageing yet affluent customer base) another factor could be improvements in coatings, allowing complex multi-element designs that would previously have been disqualified due to excessive transmission losses.

I don't know if Nagler eyepieces are compact! The Nagler 31mm is about the size of a hand grenade!

 

[Maljunulo]

………… improvements in coatings, allowing complex multi-element designs that would previously have been disqualified due to excessive transmission losses.

Good point, I never thought of that.

 

[BKoh]

I don't know if Nagler eyepieces are compact! The Nagler 31mm is about the size of a hand grenade!

Type 6 Naglers (2.5-13mm) are compact, they work in binocular telescopes and binoviewers.

Nagler 82° Apparent Field Eyepieces

The goal is to allow the telescope to virtually 'disappear,' leaving the impact of 'spacewalk' viewing.

www.televue.com

 

[Tryglo]

and yet it seems that both were suddenly in development at about the same time?

Years ago I was told by the chairman of a large division of a multi-national (not an optics business) that they had a number of products developed and ready to be put into production, but were holding back from doing so. As the market leaders they had no great incentive. Why incur the production, distribution and marketing costs of a new world-wide launch when they were already the market leader? However, when one of their main rivals were ready to launch a new product which might leap-frog them as market leader, they would launch their previously developed upgrade at the same time, in order to blunt the impact of their rivals launch and maintain their dominant position. Is it possible that this kind of business strategy is playing out here?

 

[tenex]

another factor could be improvements in coatings, allowing complex multi-element designs that would previously have been disqualified due to excessive transmission losses.

I did think of that but NL has either the same number of elements, or just one more than EL -- I'm sure John Roberts has posted the cutaways but am too lazy to find them at the moment. So I don't easily see how it can be a matter of new technical developments, except possibly some sort of new aspheric field flattener? (Likewise, decades ago Porro models got by with very simple eyepieces when better designs were known. Zeiss didn't improve their 15x60 until 1994(?) when it was really too late.)

However, when one of their main rivals were ready to launch a new product which might leap-frog them as market leader, they would launch their previously developed upgrade at the same time, in order to blunt the impact of their rivals launch and maintain their dominant position. Is it possible that this kind of business strategy is playing out here?

Yes, a very plausible suggestion, at least for explaining how closely NL followed upon SF. But it still seems that this idea of greater FOV was already in mind as the next step. Perhaps it's more obvious than I think... what other easily noticeable improvements are still possible?

 

[[email protected]]

I think it is just a natural progression of pushing the envelope of the technology they already have. The EL and FL already had pretty big FOV's, so it isn't that hard to increase it incrementally, but I think every optical improvement has its tradeoffs, as we have seen with the glare issues in the NL. Sometimes I think instead of trying to have the biggest FOV the manufacturers should concentrate more on the quality of the view and try to reduce glare and the aberrations that can come with these increasingly huge FOV's.

 

[tenex]

I've always felt that FOV matters, that 60° or so really isn't enough to feel "wide angle", so it seems exciting especially for birding that a 10x NL (or 10x32 SF) can also offer the FOV more typical of 8x models. (That said, I don't think one needs much more than 70°.) And modest FOVs are more a matter of compromise for marketing/pricing than optical design priorities, which of course is the sort of thing that makes alphas generally more interesting.


... Here's another related question: I wonder why SF 32s manage to improve on the 42's FOV in both cases, whereas the 10x32 NL barely does and the 8x can't even match it. Does this reflect some relevant difference in overall optical design between SF and NL?

 

[jafritten]

... what other easily noticeable improvements are still possible?

I think the most useful improvement would be image stabilisation in a more or less normal body.

 

[Patudo]

Wide field has always been a prized quality in binoculars. Leaving aside oddities like the 6x42 SARD, Zeiss's pre-war 8x40 with the 11 degree field of view, and the very first Trinovids, Zeiss's popular 8x30 and 10x50 made 150m at 1000m and 130m at 1000m (respectively) something of a standard. Wide field has been around for decades - just not in combination with long eye relief and flat field/sharpness to the edge. Long eye relief designs resulted in quite significantly reduced fields of view at first, but both field of view and sharpness to the edge were gradually improved until now the SF gives us fields of view comparable to the old standards and the NL a little more, with far superior edge performance.

One wonders how much room there is for improvement. The field of view of my old Swift 766 still impresses me, and I regret that the necessity to remove my glasses to use it, and 7x mag being a little underpowered for most of my birding, mean that I don't use it much. If edge sharpness was improved it would really be quite something. I do in fact find its edge performance quite acceptable at shorter distances, but the further away the target, the smaller the sweet spot seems to be.

 

[[email protected]]

I have lost the desire for larger and larger FOV's. Anymore I would rather have quality over quantity in my view.

 

[Binocollector]

For astronomy I love a large FoV but it needs to be sharp to maybe 60-70 percent. For birding I find it less important personally and rather have a bit less FoV but sharp to the edge. That being said - some of my favorite wide angle binos have such a large FoV that I don't care if the edges get blurry. Those are all vintage 8x30s.
I'm fine with anything around 60° AFoV (simple formula).

 

[Jessie-66]

Is there a relevant technical advance, and why didn't it happen years ago? (this is what I'm most curious about...)

Hi tenex,
I also think that this has to do with the much better and faster computer-calculation of optics that has recently become possible. I have picked out a link that only deals with cropping edge rays. I have thought of modern extreme wide-angle binoculars.

Fernoptik

(section register "Sehfeld" ~ field of view in English)
best regards
Jessie

 

[kimmik]

I just read Lee's interview with Zeiss for the launch of SF 32, the optic designer indirectly mentioned aspheric elements are being used.

Interview with Zeiss Senior Optical Scientist

Continuing my series of interviews with people in the optics world, this time I have been lucky that Thomas Steinich of Zeiss has been willing to donate his time and take part. Troubador: Herr Steinich please tell us your official job title and how long you have been in this job. Thomas...

www.birdforum.net

 

[John A Roberts]

Hi kimmik,

Maybe or maybe not

The only reference seems to be where Thomas Steinich is discussing optical design considerations in general,
before Lee asks about the SF32.
(Earlier on it's noted that Thomas was also involved in the design of a high-end camera lens and the Harpia spotting scope.)

The full paragraph is:
'In general optical design is the process of finding a lens (and in the case of a binoculars also a prism) distribution that is able to
a) achieve the given specification that come from the markets needs and
b) works as a real-life product and not just on paper.
At ZEISS we are in the comfortable position to have all commercial optical design software tools available and even have an in-house software that is specialized on the products we have.

When you start a product design you typically do the bottom-up strategy: you need a deep understanding of the individual parts of your system like objective, prism and eyepiece and then you start with the most simple setup you can think of, so for the objective you can start with a single positive lens.

After changing the available variables like radius, glass, thickness you increase complexity step by step, e.g. from a single lens to a doublet – split doublet – even more lenses or aspherical shapes. This process is 100% driven by the designer.

The software evaluates and helps you to find the best solution in the trade-off between performance/complexity and cost/mechanical constraints.'


John


p.s. And at least one of the Harpia eyepieces has a lens with an aspheric surface.
See a screen grab from Boris in post #237 at: New scope from Zeiss...

 

[pbjosh]

I am not an optical engineer but am an engineer (mechanical and electrical) by training. If I had to guess there are numerous “advancements” available in the quiver at all the big optics makers and it is more an issue of how much improved manufacturing and tolerances can facilitate achieving a goal at a cost that makes business sense, and how much design can be sped up with computational tools in order to try new things. Glass properties/quality/tolerances, and manufacturing tolerances are probably, if I had to guess, advancing linearly. As well, if I had to guess, computational design and simulation is probably advancing much more quickly, allowing for designs that better optimize what is available in terms of materials into a product that wows consumers but can be manufactured at a cost that allows profit. This is just speculation but I strongly doubt there is one simple answer here, and more a combination of many factors beyond and above things like I am guessing at.

 

[has530]

This process is 100% driven by the designer.

The software evaluates and helps you to find the best solution in the trade-off between performance/complexity and cost/mechanical constraints.'

To me this hints at where the next big advancement may come. Computers are able to evaluate optical performance and given "desirable" parameters to optimize I would imagine we are on the cusp of machine learning driven optical design (if it isn't already happening at least at an optimization level). It is already done in hydrodynamics and can come up with really innovative designs as computers don't have cognitive bias about what design "should" look like.