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

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Old Friday 14th February 2020, 19:33   #26
wdc
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So, where is that product? Is the world waiting for it? (or just a handful of binogeeks?)
Its as if the last step in this evolution is to go back to square one, and modernize what worked so well in the first place. After that: game over!

Or, we just lounge around Omid's New Horizons cafe and wait for some news...

-Bill

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Old Friday 14th February 2020, 22:18   #27
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Or, we just lounge around Omid's New Horizons cafe and wait for some news...

-Bill
Why just seat around and wait for me? You -and others- can actually participate in the innovation process.

I assure you that established companies such as Zeiss, Swarovski, Nikon, Leica, etc. are going to continue the exact same trajectory that they have followed in the past 30 years. If you simply lounge around and wait for "someone else" to innovate, we'll get -at best- what you predicted: go back to square one, and modernize what worked so well in the first place. The worst case scenario is that these companies will simply stop making binoculars and focus on more lucrative product sectors.

A significant innovation in binoculars, if possible, will likely come from sources outside major optical companies. Here is an example topic to think about: Why do we need to focus our binoculars? Seriously, why is focusing necessary?! Think about this question and write your answer in New Horizons please.

Happy Friday
-Omid

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Old Friday 14th February 2020, 22:32   #28
Alexis Powell
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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
I know porros didn't suffer as much as those roofs with internal focusing, but the performance of ED porros, such as the ED version of the Swift Audubon, as well as some models from Celestron, were impressive.

--AP
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Old Yesterday, 00:23   #29
wdc
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Originally Posted by Omid View Post
Why just seat around and wait for me? You -and others- can actually participate in the innovation process.

I assure you that established companies such as Zeiss, Swarovski, Nikon, Leica, etc. are going to continue the exact same trajectory that they have followed in the past 30 years. If you simply lounge around and wait for "someone else" to innovate, we'll get -at best- what you predicted: go back to square one, and modernize what worked so well in the first place. The worst case scenario is that these companies will simply stop making binoculars and focus on more lucrative product sectors.

A significant innovation in binoculars, if possible, will likely come from sources outside major optical companies. Here is an example topic to think about: Why do we need to focus our binoculars? Seriously, why is focusing necessary?! Think about this question and write your answer in New Horizons please.

Happy Friday
-Omid
All good points, and appreciate your thinking, Omid. I would still like to see a little bit of revisiting the past and improving upon it, if only for selfish reasons: I'd like a state of the art Porro that fits me! (and has the inherent capacity to outperform the roofs)

As to your question about focus, I'm hoping that will elicit a response from Bill Cook. That may rouse him from his torpor.... But I will think about it as well.

Have a good weekend.

-Bill
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Old Yesterday, 15:41   #30
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The photo below is posted with permission of Cory Suddarth of Suddarth Optical.

According to Cory:
"They are not all from equivalent apertures. The left is the Schmidt-Pecan from a compact. Middle is an Uppendahl used in all Leitz Trinovids, and the big Abbe-Konig On the right is from a Made in Japan, 9x63 roof prism model. "


It would be pretty obvious why manufacturers would gravitate towards the S-P IF the prisms were all meant for the same aperture.

-Bill
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Old Today, 01:33   #31
Chosun Juan
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Quote:
Originally Posted by wdc View Post
The photo below is posted with permission of Cory Suddarth of Suddarth Optical.

According to Cory:
"They are not all from equivalent apertures. The left is the Schmidt-Pecan from a compact. Middle is an Uppendahl used in all Leitz Trinovids, and the big Abbe-Konig On the right is from a Made in Japan, 9x63 roof prism model. "


It would be pretty obvious why manufacturers would gravitate towards the S-P IF the prisms were all meant for the same aperture.

-Bill
Bill, this is getting where I'd like to see this thread go.
We should also consider all prism types including Porro II, Perger etc.

There are only a few major factors to consider, with:-
Size/weight/packaging-offsets, and,
Transmission/micro-contrast/colour rendition
being among the main ones.

I think it would be most useful to describe the volume of each of the prism types in terms of an entrance circle to the prism of aperture diameter dimension 'A'.

That way everything is represented by a formula with reference to 'A' and we can have an apples to apples comparison between the different prism types. By multiplying the resultant volumes by glass density for each prism component it gives us the weight for each prism type - by assigning a millimetre figure to the aperture dimension we get actual weights in grams.

There will be some subtleties which determine the precise aperture diameter required, such as power of the lenses in the objective/focusing group (internally pre-prism focused) , the focal ratio of the binocular , and any effects on that due to physical length of the packaging etc, but largely this will have minor effect on 'A' and may be able to be dealt with via a %factor in practice (bearing in mind this affects Fov which for the purpose of discussion we should try and standardize as much as possible).

It also allows us to define offsets, and physical packaging dimensions also as a multiple of the common parameter 'A' for each prism type.

In the big Zeiss SF thread I know we briefly discussed this for some prism types, with Holger chiming in with some calculations, but it would be very interesting to encompass every type of prism in a standardized way.

Similarly for the other transmission factors etc. I'm on the record as saying that I find 100% internally reflecting prisms to offer the desireable though somewhat esoteric quality of 'clarity'. This will be subtle differences in transmission at various wavelengths, and the effects of lost light on micro-contrast and glare, etc. I know that we are well into the realm of stacking BB's, but hey, I see tree spirits, and other etheric energy at times, have been known to leave my body to fly around up in the sky, and even though my eyes are the same colour they each have their own colour cast particularly around afternoon light into dusk. I readily see CA too - so pardon me if I march to a different beat !

Even though the best 70+ layer dielectric mirror coatings may lose ~1~2 odd % transmission, given that light losses through glass at different wavelengths occurs at different amounts, it may also offer the additional potential for 'retuning' these losses somewhat to offer a flatter transmission curve. I'd like to see some data on that if we can access it (highly doubt it - lol:).

This would provide a better framework for analysis than 50 million people going around in circles with one 'I reckon' in response to another.





Chosun

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Old Today, 01:40   #32
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Just why are prisms even needed in the binocular today?
Modern lenses are plenty good enough to provide a full range of magnification without the extra path length the prisms provide, if camera lenses are any indication.
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Old Today, 01:53   #33
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Depends on how you define "significantly" ...
Indeed. Is the difference in micro-contrast between a well-executed Schmidt-Pechan design and an Uppendahl likely to be discernible only by nitnoids/BB-stackers like our friend denco, or is it likely to be apparent to the average binocular user?

If Leica could make available a Retrovid with the 20% of Uppendahl prisms that passed QC for comparison with the current version, it would be most interesting to have our esteemed contingent look through them - preferably not knowing which was which...

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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."
I found the above comments really interesting as I had the pleasure of doing a similar comparison - between those same two models - last year. It was a fine autumn day and my main target was the BT Tower, a well-known London landmark about 1km away; lots of little details to compare and contrast betwen the two. Having these two classic models of different eras and designs side by side for some 20 minutes or so was a really enjoyable experience, and I wish I had noted down my impressions in detail. I found the Oberkochen porro comparable in brightness (x50 objectives vs x40 making up for T vs T* coatings, I suppose). Colour rendition at that distance, somewhat to my surprise, was very similar - I had expected the older pair to show more subdued colours at distance (as my 8x30 non-B porro did when compared against the 8x30 SLC mark II I used to own). Resolution, I thought, was very similar between the two, although I need to note that I was wearing glasses (my left eye has slight astigmatism) while using the Dialyt and using the Zeiss West porro straight to my eyes. I really enjoyed both the excellent field of view and the immersive experience of using these old short eye relief porros - the surroundings being blacked out by the eyecups so you feel like you are in a cinema. But being able to observe with glasses on was unquestionably more convenient.

My strongest impression after comparing the two was how the 10x50, despite being around 30 years older, was so close, image-wise, to the 10x40 - a real testament to the intrinsic soundness of the porro design and Zeiss West's ability to build a really good 10x50. The 10x40, however, delivers the same image (to me) in a much handier and more convenient package that gets used quite a bit more. I admire the 10x50 a great deal, but if I had to choose between the two, would keep the 10x40.

I agree that a multi-coated version of the 10x50 would be superb - but whether it would "hands down" beat the very best of today's 10x50 roofs...

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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.
If I could ask what advantages these are, and how they would become visible - I would be very much obliged.
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Old Today, 03:04   #34
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Just why are prisms even needed in the binocular today?
Modern lenses are plenty good enough to provide a full range of magnification without the extra path length the prisms provide, if camera lenses are any indication.
A simple answer might be to make the image erect, and right reading.

No prism and it will be upside down. With a mirror diagonal it will be upright, but flopped. Telescope finders use an amici prism to erect the image properly, as far as I can recall.

-Bill
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Old Today, 11:35   #35
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Bill, try this on for size. The posts around this one contain volume formulas for S-P, A-K, Porro, and Perger, prisms. (referenced in terms of 'w' for the 'A' that I suggested).
https://www.birdforum.net/showthread...89#post3059689




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Old Today, 17:00   #36
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I'm on the record as saying that I find 100% internally reflecting prisms to offer the desireable though somewhat esoteric quality of 'clarity'. This will be subtle differences in transmission at various wavelengths, and the effects of lost light on micro-contrast and glare, etc.
I'll second that. But I have to admit I'm not very interested in details of the relative volumes of prisms etc, because that boils down to asking how much effort TIR prisms are worth. My only question is, if a bino is large enough to accommodate them, why hasn't it got them? Then we can just quibble about where the line of "large enough" is. Clearly 50/60mm aperture is large enough; 40 probably is too if you're willing to have it modestly longer, as I would be; 30, not so much.
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Old Today, 19:28   #37
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A simple answer might be to make the image erect, and right reading.

No prism and it will be upside down. With a mirror diagonal it will be upright, but flopped. Telescope finders use an amici prism to erect the image properly, as far as I can recall.

-Bill
So how do rifle scopes and cameras manage this issue?
Is it not simply a matter of adding an extra lens?
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