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Prisms! S-P, Uppendahl, Abbe-Koenig..

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Old Thursday 13th February 2020, 19:01   #1
wdc
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Prisms! S-P, Uppendahl, Abbe-Koenig..

S-P prisms are referred to as widely available, therefore inexpensive, but can in some incarnations, seemingly produce excellent results in a binocular. In other words, they may have inherent flaws or drawbacks, but they have not prevented manufacturers from producing a very high quality product.

Would any of the current well-regarded binoculars on the market benefit significantly from the use of a different prism? Zeiss Victory SF, Swarovski EL 8.5 x 42, Nikon MHG, Leica Noctivid?

Abbe-Koenig reduces the # of reflective surfaces, but weighs more, and takes up more space, but is still present in 42mm offerings by various manufacturers. If they were shoehorned into an 8x32 format, would they weigh anymore than a Leupold Gold Ring?

Uppendahl prisms: What are their inherent strengths and weaknesses? Why aren't they used more? And why are they still being used?

It seems binocular performance is a sum of components, and prisms are just one part of an intentionally designed optical system. I don't expect miracles from any one element in the chain. I welcome any and all opinions on this. Educate me, please.

-Bill
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Old Thursday 13th February 2020, 21:27   #2
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I'm grabbing my popcorn waiting for the inevitable.
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Old Thursday 13th February 2020, 21:53   #3
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I hear you, but I hope that storm has passed. I'm not looking for a flame war. What interests me is that there are ongoing discussions, praise and criticism, of various prisms in use (or not, as in the case of the Retrovid), and whether, in one sense collectively, as binocular users, is there a reason, besides staying in business, for one to be preferred over another?

I'm doing my own homework in my spare time. Plenty of folks on this forum have contributed to threads in the past, which examined various prisms, and the bins they lived in.... I spent part of my lunchtime reading about Uppendahl prisms, and the well-regarded Bausch and Lomb Elite, which apparently was 'derived' from the Trinovid. I've yet to determine for sure if the B&L actually had an Uppendahl prism! In fact someone on that thread pointed out that there was room in the case for an S-P... Many familiar names in the thread, including some that are on the Retrovid thread! This was 9 years ago... I get why those folks are disappointed, in that they wanted the updated original.. better coatings and possibly glass, with the same configuration.
Instead they got the Fender Stratocaster made in Mexico, with lace sensor pickups, and a really nice looking tweed case. A good instrument, but not what they wished for! One thing I've learned so far, and Lee mentioned as much earlier today in a Meopta thread, is that modern coatings have minimized the advantage of fewer reflective surfaces to a great extent.

At any rate, I'll keep reading up, and post links later, but I welcome anyone to weigh in on the issue.

-Bill

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Old Thursday 13th February 2020, 22:27   #4
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The AK spammer will be along shortly........
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Old Thursday 13th February 2020, 22:54   #5
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.....
.....
.....

Would any of the current well-regarded binoculars on the market benefit significantly from the use of a different prism? Zeiss Victory SF, Swarovski EL 8.5 x 42, Nikon MHG, Leica Noctivid?

.....
.....
Since you qualified your question by inserting the term „significantly“, my answer is: NO.
They wouldn‘t produce significantly brighter images or more contrast, nor would they be cheaper.

As you say, A-K prisms have by their very design some advantages over S-P prisms, and the same will be true to some degree for Uppendahl. But due to technological progress in other fields (coatings, glass manufacturing, etc.), such advantages are today less relevant than 20-30 years ago. So similar performance can now be achieved with various designs.

Just my 2 ct.
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Old Friday 14th February 2020, 00:26   #6
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Since you qualified your question by inserting the term „significantly“, my answer is: NO.
They wouldn‘t produce significantly brighter images or more contrast, nor would they be cheaper.

(snip)

.... So similar performance can now be achieved with various designs.

Just my 2 ct.
Canip
Thanks Canip. Makes sense. I get the feeling that top models, even beyond what are normally considered alphas, are pretty much neck in neck with regards to performance capability, with various considerations for weight vs. extra glass for corrective purposes, or to attain a wider FOV, exit pupil, etc.

Of course, in addition to performance, their build quality, and price point specifications from the commercial side, but thats sliding off topic.

Perhaps the entire topic is an oft-beaten dead horse, to be dragged out into the village square periodically and flogged some more..

The only other thing I can think of is the porro....



-Bill
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Old Friday 14th February 2020, 00:28   #7
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The brightness advantage of other prisms like AKs seems to have been largely made up for as you say, and I think I've only heard one person claim that they offer greater "contrast". But the nagging point I've also heard mentioned here is that the dual reflective/transmissive surfaces of SP prisms compromise the resolution of fine detail. I'm not aware that this has also been solved by improved coatings.

All that said, Zeiss has continued to use AKs in the HT series (if it is a series anymore?), as Swaro does in the SLC 56s, and one assumes they had reasons for doing so. (The various Kamakura rebrands also do now.) It would be interesting to hear what their thinking was, and still is, on that.
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Old Friday 14th February 2020, 00:37   #8
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Hello,

The almost vanished Zeiss FL series had AK prisms except for 8 and 10x32, which used S-P prisms. I would venture to guess that Zeiss had good reason not to use AK in those glasses. Weight and overall size may have been the reasons. Zeiss has yet to replace those 32mm binoculars.

Happy bird watching,
Arthur
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Old Friday 14th February 2020, 01:06   #9
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I'm posting a link to a BF thread from 2006, which includes some current contributors on the forum, who are tolerant enough to still post here. I've read through this thread twice, because its really informative, articulate, and generally represents folks being their best selves as well. Whats surprising is that in 14 years there have not really been any big technical advancements in optics, as it applies to what is currently on the market, from what I can tell.

The comment on light transmission perception thresholds are particularly informative, as they may play into why manufacturers have gone down certain roads leading to today's products.

Enjoy, and thank you Henry Link, Bill Cook, Elk Cub, Pileatus,and Pinewood, (among others whom I'm not familiar with)
for contributing to this thread.

https://www.birdforum.net/showthread.php?t=63770
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Old Friday 14th February 2020, 03:07   #10
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Originally Posted by Samolot View Post



I'm grabbing my popcorn waiting for the inevitable.

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Originally Posted by wdc View Post



I hear you, but I hope that storm has passed.



I'm not looking for a flame war.


.. better coatings and possibly glass, with the same configuration.

Instead they got the Fender Stratocaster made in Mexico, with lace sensor pickups, and a really nice looking tweed case. A good instrument, but not what they wished for!

At any rate, I'll keep reading up, and post links later, but I welcome anyone to weigh in on the issue.

-Bill
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The AK spammer will be along shortly........
Quote:
Originally Posted by wdc View Post

I'm posting a link to a BF thread from 2006, which includes some current contributors on the forum, who are tolerant enough to still post here.

https://www.birdforum.net/showthread.php?t=63770


Being a 2-3 post "Newb" in here - But experienced on other fora/forums, I read Sam's opening with trepidation.

I thought, "Jeeez, obviously there's been some 'FLAK' flying around here in past times".

Have seen it (all), before - Where some folks "wade-in" & give their "Holier Than Thou" opinion(s).

Had it last-week with an Australian pilot, barely out of school (& quite frankly, barely out of nappies/diapers !)

Bit hard to take, when a kid barely out of school & living with his parents (i.e, "still wet behind the ears"), gets his pilot's license,
....chats to the lads in the "Live Chat" room (International)....

Then, barely TWO years later, starts sounding-off like a &%*£$** "Expert"

Can't stand that poncy kinda "Holier than thou" stuff, from someone less than a third my age, who's been "airborne" for 5-mins !


Anyways, this....


I "WAS" (as in, past-tense now), gonna start & open a thread on several (TWO), brand-new sets of binoculars I've bought, which rather surprised me with their quality, put-up against their comparatively low-middling price.

(The company concerned are from Dresden in Germany & were more well-known for their cameras)


However = Seeing you guys (collectively), posting the above, made me 'slam on the brakes' & ABSTAIN !


Bill, I rather liked your analogy of the 'Mexican Fender Stratocaster(s), given I've got six of them, myself.

Mine are all 'top of the standard-USA-range', full-blown USA Corona models, bar ONE.

The 'One-Exception' was a brand-new 1999 Indonesian Strat'

Bought 'New', it cost just 1/10th the price of the other five !

Fit & finish was AMAZING & had seriously no-right to BE & PLAY as well as it did/does.

Admittedly certain bits of the hardware (tuners/bridge-saddles), are NOT of the same quality...

First time I used it, was in front of a crowd of 900+folks

I used the 'cheapie' Indonesian for the 1st-set & my USA Olympic-White for the 2nd-half.

Folks were STUNNED that I'd used a "cheap" guitar, just 1/10th the price....
("it sounds great" or "you're kidding me, right ? = the kinda reactions I got)


Anyways, back to binoculars = I know these are no Leica or Zeiss, but they work for me.

Couldn't be arsed to buy a second-hand set, only to find mold-spores or mild-fungus, clouding, or what-not.

Hence as to 'why' I bought a couple of lower-middling pair, from this Dresden company.

Was gonna post-out, purely as a lower-middling priced recommendation for other birdwatchers, NOT on a high budget.


However ; Seeing all you lads posting, I can HEAR the collective 'Groan' that's evidently gone before (laughs !)

Folks here (upon my 'entry' to this forum), last-week, have been nothing but kind & friendly.

But whether it's Gibson vs Epiphone, or camera-gear snobbery (& now, Binoculars), I've seen flare-up's, before.

Been told it'll take over ten-posts, before I can upload an Avatar (probationary-period ?)

I'll aim for a 2021 upload then as mah post-count remains along (below), the radar

Am grateful I caught this thread, prior to posting ANYTHING binocular related !

As they say ; Forewarned is Forearmed - (or, is it the other way round ? )

.

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Old Friday 14th February 2020, 05:34   #11
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Being a 2-3 post "Newb" in here - But experienced on other fora/forums, I read Sam's opening with trepidation.

--------------
Am grateful I caught this thread, prior to posting ANYTHING binocular related !

As they say ; Forewarned is Forearmed - (or, is it the other way round ? )

.
Welcome to the forum, Hornchurch. Sorry the tenor of the posts put you on heightened alert. I don't think comments of that sort are a regular occurrence.
I'm probably considered a newbie myself here, since some of these folks have been around well over a decade, and know far more about binoculars and optics than I'll ever know. I consider this forum a great resource, and folks are from all over the planet, with a common interest in binoculars. Being a sub-forum of 'bird forum, its fair to say that there's a lot of birding overlap, as well as astronomy related.... optic-based, visual discussion.

I agree there is that continuity of obsessive 'stuff... gear fetishism' and all that goes with it, be it fly-fishing, stereo gear, musical equipment, cars, cameras... pilot talk....
Yep, you will find it here as well. So, it should be familiar territory to you in that regard (the good, and periodically the irksome)

Lot's of good folks here though, as you may have already discovered.

I looked up binoculars made in Dresden, and could not find anything but antiques! So, you have some mystery bins, as far as I can tell.
The best tip I can give you right now is this: If you are satisfied with your purchase, then abandon this forum and run like the devil, because folks around here will tempt you into spending your hard earned money on 'better' binoculars... Its a dangerous place! (you've been warned) However, truth be told, there is common agreement that many less expensive binoculars can do a great percentage of what the pricier ones do. (as you've already discovered with guitars...)

It helps to read through threads on the forum, as well as search the forum for topics, or binoculars that interest you. In that way, you'll probably get a good sense of
what this forum has to offer in terms of useful information, and how this group interacts. It is kind of like a squabbling apartment house at times... Other times utterly serene. All depends!

Cheers,

Bill

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Old Friday 14th February 2020, 09:40   #12
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They wouldn‘t produce significantly brighter images or more contrast, nor would they be cheaper.
Depends on how you define "significantly" ...

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As you say, A-K prisms have by their very design some advantages over S-P prisms, and the same will be true to some degree for Uppendahl.
The AK has got one significant advantage over all the others: It relies on total reflection at a glass to air surface, not on a coated reflecting surface (e.g. a silver coating, nowadays most dielectric coatings). Total reflection is by definition lossless. Reflective surfaces are not. One further potential disadvantage of the SP is a loss of micro contrast, cf. Konrad Seil's article (Proc. of SPIE Vol. 1533, Optomechanics and Dimensional Stability, ed. R A Paquin, D Vukobratovich, Dec 1991).

One disadvantage all roofs share is that they need to be very precisely made. The tolerances of a good old porro prism are larger. All roof prisms also require phase coatings that may or may not be 100 percent efficient.

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But due to technological progress in other fields (coatings, glass manufacturing, etc.), such advantages are today less relevant than 20-30 years ago. So similar performance can now be achieved with various designs.
I totally agree. Many modern roofs - not matter which prism type they use - provide excellent image quality.

I do, however, believe a well-made porro will have optical advantages over any roof. And these differences will be visible. Sadly, there are no truly modern high-quality porros on the market anymore.

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Old Friday 14th February 2020, 14:59   #13
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Hermann, post 12,
Did you forget the Swarovski Habichts? They are excellent porros.
Gijs van Ginkel
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Old Friday 14th February 2020, 15:46   #14
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I do, however, believe a well-made porro will have optical advantages over any roof. And these differences will be visible. Sadly, there are no truly modern high-quality porros on the market anymore.

Hermann
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Hermann, post 12,
Did you forget the Swarovski Habichts? They are excellent porros.
Gijs van Ginkel
I think some of the issues with the Habicht, as has been pointed out before, is poor eye relief, a very stiff focuser, and in the case of the 7x42, an absurdly narrow FOV for a format that is usually known for having a wide one. Of course it was designed that way, for a narrow group of users.

At least they still make them, as do Nikon, I suppose, unless they've farmed those out to Kamakura.. Are Swift Porros still in production? It seems they at least got as far as ED glass...

Maybe the Porro is the best candidate, if one was to set about crafting a 'better' binocular, which I acknowledge is a can of worms in itself. One good thing to consider is that the 'retro style' that is in vogue could very well embrace this type of artifact, so it may very well happen, with or without any input from dedicated users. Food for thought.

-Bill

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Old Friday 14th February 2020, 15:53   #15
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Canon 10x42L IS.
A very good Porroprism binocular.

B.
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Old Friday 14th February 2020, 16:22   #16
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Did you forget the Swarovski Habichts? They are excellent porros.
Gijs: I didn't forget them ... I've got three of them myself, and they're excellent. In fact, I'd rate the 10x40 optically as better in the image center than any 10x roof I'm familiar with.

However, to qualify as "excellent, modern porros" they'd need a couple of upgrades:

- Slightly more modern eyepieces that provide a bit more eye relief and, in the case of the 10x40, a slightly flatter field. The old Erfles of the 10x40 don't cut it anymore.

- Somewhat bigger fields of view, especially the field of view of the 7x42 (optically a killer binocular!) is definitely too narrow.

- A smoother focuser, so they'd need a different way of making them waterproof or at least splashproof. Zeiss used rubber seals in the porros of old making the binoculars at least splashproof, their focusers were great.

That would do nicely, I don't need screw-out eyecups or very close focusing distances.

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Old Friday 14th February 2020, 16:24   #17
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Are Swift Porros still in production? It seems they at least got as far as ED glass...
Actually, a well-made porro doesn't need ED glass. The problems with CA only reared their ugly head when the manufacturers introduced focusing lenses behind the objective lenses.

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Old Friday 14th February 2020, 16:25   #18
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Canon 10x42L IS.
A very good Porroprism binocular.
It's excellent. But it's shaped like a brick and the weight of a brick.

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Old Friday 14th February 2020, 17:16   #19
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Actually, a well-made porro doesn't need ED glass. The problems with CA only reared their ugly head when the manufacturers introduced focusing lenses behind the objective lenses.

Hermann
Good point!
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Old Friday 14th February 2020, 17:32   #20
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Canon 10x42L IS.
A very good Porroprism binocular.

B.
Hi Binastro, Yes it is. And like Hermann says, it is probably a brick, though less of a brick than the 15 x50 'all weather' IS I've had for about 14 years, which I purchased during my astro period . I still haul that bugger up to the Sierra back country on pack trips to share some deep sky views with others. I point them to spots in the sky with a laser, and they find their way, and go 'ooh!'

Back then I observed without glasses, and to use that model now, I still have to do that. IPD is also 'conservative'.

When I first started looking into binoculars for birding, I was very curious about trying out well regarded models like the Nikon E and SE, the Swift Audubons, but quickly came to realize that either eye relief, IPD, or both combined to make them unworkable for me. Those are 2 of the issues I'd really like to see improved upon in an upgraded porro.

-Bill
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Old Friday 14th February 2020, 17:34   #21
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Gijs: I didn't forget them ... I've got three of them myself, and they're excellent. In fact, I'd rate the 10x40 optically as better in the image center than any 10x roof I'm familiar with.

However, to qualify as "excellent, modern porros" they'd need a couple of upgrades:

- Slightly more modern eyepieces that provide a bit more eye relief and, in the case of the 10x40, a slightly flatter field. The old Erfles of the 10x40 don't cut it anymore.

- Somewhat bigger fields of view, especially the field of view of the 7x42 (optically a killer binocular!) is definitely too narrow.

- A smoother focuser, so they'd need a different way of making them waterproof or at least splashproof. Zeiss used rubber seals in the porros of old making the binoculars at least splashproof, their focusers were great.

That would do nicely, I don't need screw-out eyecups or very close focusing distances.

Hermann
Yes to all those suggestions..... except I'm not sure about the eyecups. If there's enough eye relief for the likes of me, others will probably need to back out the eye cups.

My benchmark for close focus is whether I can hit the bird feeder from the kitchen! Non-negotiable!

-Bill

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Old Friday 14th February 2020, 17:45   #22
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I'm posting a link to a BF thread from 2006, which includes some current contributors on the forum, who are tolerant enough to still post here. I've read through this thread twice, because its really informative, articulate, and generally represents folks being their best selves as well. Whats surprising is that in 14 years there have not really been any big technical advancements in optics, as it applies to what is currently on the market, from what I can tell.

The comment on light transmission perception thresholds are particularly informative, as they may play into why manufacturers have gone down certain roads leading to today's products.

Enjoy, and thank you Henry Link, Bill Cook, Elk Cub, Pileatus,and Pinewood, (among others whom I'm not familiar with)
for contributing to this thread.

https://www.birdforum.net/showthread.php?t=63770
I think most of us on that old thread have learned a few things about optics since 2006, but if it isn't obvious already I would caution newbies to take the long rambling posts from ksbird/foxranch with a very big grain of salt. If they seem a bit off it's because they are a bit off. He/she/they (I was never sure which) was/were the first of several posters down through the years who seem to have come here from some parallel optics universe with fantastical stories and ideas to share with us. You might say the Rico70 of their day.

Henry

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Old Friday 14th February 2020, 18:12   #23
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Whats surprising is that in 14 years there have not really been any big technical advancements in optics, as it applies to what is currently on the market, from what I can tell.
First, a minor correction: There has been little meaningful progress in binoculars since mid 1990's (introduction of Zeiss Design Selection series, Leica Trinovid BA series). That's nearly 30 years of having "nothing new" yet "us talking a lot" about binoculars Second, it is not surprising. The minimum value of an "error" is zero. You cannot minimize binocular errors (we call them aberrations) indefinitely. Third, search for new horizons; you shall find "hope" there

-Omid

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Old Friday 14th February 2020, 18:54   #24
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Yes to all those suggestions..... except I'm not sure about the eyecups. If there's enough eye relief for the likes of me, others will probably need to back out the eye cups.
Actually, there was a time when some manufacturers offered rubber eyecups in different lengths.

Problem solved.

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Old Friday 14th February 2020, 19:23   #25
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First, a minor correction: There has been little meaningful progress in binoculars since mid 1990's (introduction of Zeiss Design Selection series, Leica Trinovid BA series).
Well ... if you disregard the roofs for a moment and just look at optical performance, I'd argue there hasn't been all that much progress in the past 70+ years. Some of the old porros could easily compete with today's crop of alphas - if they had modern multicoatings.

With roofs it's different, before the introduction of phase-coatings in the late 1980s they were pretty awful by today's standards.

Just for fun an excerpt from the archives of Peter Abraham's mailing list (http://www.europa.com/~telscope/binotele.htm):

"I got my first pair of roof prism binoculars with phase-coated prisms, a pair of Zeiss 8x30B's, immediately after Zeiss started selling them, and I found the difference in direct comparisons to older Zeiss 8x30's quite marked. It was basically just as Weyrauch/Doerband had written in their paper - better resolution, slightly higher contrast, overall a "more pleasing image".

Last autumn I finally had a chance to do a more detailed comparison. We (a couple of fellow birders and I) got together for a weekend trip, and as there wasn't much about we had the time to do a detailed comparison of three different Zeiss 10x40B's. The first one was bought in 1979. It doesn't have T* coatings and the prisms are not phase-corrected. The second one was bought in 1981, with T* coatings but still without phase-corrected prisms. The third one was purchased in 1998, so it has both T* coatings and phase-corrected prisms.

The interesting thing about this comparison was that all three binoculars were of the same make and had the same specifications, so all the differences observed were caused by the different coating technologies used. We compared the binoculars mounted on tripods, checking for their optical quality by looking at birds and a Zeiss standard resolution target in a variety of light conditions.

Perhaps the most interesting result initially was that the differences between the two old Zeiss 10x40B's weren't all that great. Sure, the T*-coated pair had slightly better contrast with cleaner colours and a slightly brighter image, but the difference was nothing to boast about. Even under difficult lighting conditions the difference wasn't that great. The resolution was exactly the same (as it should be), and the image of both was slightly fuzzy. This was most noticeable when checking the resolution targets.

The comparison with the pair with phase-corrected prisms was almost a foregone conclusion after these results. And sure, it had much better contrast and cleaner colours, a brighter image and quite clearly a higher resolution than either of the two pairs without phase-corrected prisms. In fact, the difference was nothing short of amazing.

I believe this comparison puts some of the claims made about modern multicoatings into perspective. Modern multicoatings are nice, but they're not the most important thing to watch out for in roof prism binoculars. Based on this comparison I'd say the most important progress has not been the development of modern muticoatings, but rather the development of phase-correction coatings on the prisms.

One other interesting observation we made was this: After we'd done our comparisons I got my old Zeiss West 10x50 Porros (~ 1963) from the car. My friends had got bored with testing optics by that time, so we only did a quick comparison with the new Zeiss 10x40B's, and the results were pretty amazing. Sure, the 10x40's had better contrast and a brighter image, after all, the old 10x50's only have a simple single-layer coating, but the resolution of the old 10x50's was quite noticeably *better*. In fact, the difference was so pronounced that we couldn't help but wonder why Zeiss doesn't make these binoculars with a modern T*-coating anymore. I'm sure they'd beat most (if not all) roof prisms hand down."

That excerpt is slightly abbreviated, I left out one paragraph.

Hermann

Last edited by Hermann : Friday 14th February 2020 at 19:26.
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