Where are the aspherics? (1 Viewer)

[Binastro]

The pupil of the eye is not comparable to a camera sensor.

If comparing, then the retina, which is curved is more comparable to a camera sensor.

The retina has varying resolution. Only the centre is fine resolution.

The pupil of the eye determines the speed of the eye's lens.
Best performance is with about 2.5mm pupil.

B.

 

[moyang_mm]

The pupil of the eye is not comparable to a camera sensor.

If comparing, then the retina, which is curved is more comparable to a camera sensor.

The retina has varying resolution. Only the centre is fine resolution.

The pupil of the eye determines the speed of the eye's lens.
Best performance is with about 2.5mm pupil.

B.

Yes, you are right. My point is that we only pay attention to the very center of the retina, whereas in cameras the entire image circle needs to be corrected.

The lenses on smartphones are much simpler (usually only 6 or so elements without ED or ASPH) because the sensor is so small.

 

[tenex]

Also our eyes are pretty lousy optically. It is just a single-element lens. But we have the most advanced image processing system, the brain, that magically mitigates all the optical issues of the eyes. This could also explain why binoculars use less sophisticated optical formulas, because the brains have already addressed some of the aberrations.

Hmm, regular complaints on this forum about CA, astigmatism, coma etc don't suggest that the brain can correct optical aberrations. But the point is well taken that binoculars are built to a lower optical standard than camera lenses because users aren't recording, enlarging, and scrutinizing their output. On the other hand, the alphas at least seem expensive enough that one could expect better...

 

[moyang_mm]

On the other hand, the alphas at least seem expensive enough that one could expect better...

I think the "alpha" binoculars are very much overpriced due to the lack of economy of scale and the lack of competition.

Look at the internals of a Canon EF 70-200mm f/2.8L IS II, which features five ED glass and one fluorite crystal, and 23 elements in 19 groups in total. It is also made in Japan. Not to mention it also has auto focus and image stabilization. Yet it only sells for about the same price as a pair of "alpha" binoculars.

 

[PYRTLE]

I think the "alpha" binoculars are very much overpriced due to the lack of economy of scale and the lack of competition.

Look at the internals of a Canon EF 70-200mm f/2.8L IS II, which features five ED glass and one fluorite crystal, and 23 elements in 19 groups in total. It is also made in Japan. Not to mention it also has auto focus and image stabilization. Yet it only sells for about the same price as a pair of "alpha" binoculars.

Yep, then multiply that by 2!

Not the same price now is it. But I see where you guys are coming from. An alpha porro prism is always going to be noticably heavier and physically larger than a roof which is not within the demographics of what the end user is after these days.

 

[Binastro]

My 1950s Kodak Brownie 127, of which millions were made in Britain, had a curved film plane but only had a meniscus lens.

It produced good 4cm x 6cm negatives.

The British Purma Plus with gravity shutter also had a curved film plane.

The eye's lens does not have to cover a flat sensor.

There are curved digital sensors but they are expensive.

B.

 

[moyang_mm]

Yep, then multiply that by 2!

A fairer comparison should be between telephoto lenses and alpha spotting scopes?

Swarovski ATX 25-60x65 costs $3775, but optically much simpler than the 70-200 f/2.8.

 

[PYRTLE]

A fairer comparison should be between telephoto lenses and alpha spotting scopes?

Yep, that would be a similar comparison in many ways, but the thread is about binoculars. CJ has answered and mirrored some of my thoughts in a previous post.

Too large, heavy and cumbersome for the modern user. No mass market or interest for any of the European alpha brands to engineer, model or produce such units. Technology moves on in a different direction.

How many Questars do you see in use for birding these days, yet in the 80s and 90s we queued up to look through one at a distant wader or whatever. A brilliant optic at that time but difficult to get used to.

 

[Binastro]

A spotting scope of high quality is made to higher optical standards than even the best camera lenses.

I have tested very large numbers of photo lenses visually and only a handful can be used at even 100x, where the Swarovski 65mm should be fine at 100x.

The only ones approaching telescope standard were a Tewe 600mm f/5 Petzval design, a Vivitar 600mm f/8 solid cat and a Soviet Maksutov lens. The Ross 50 inch f/8 was pretty good.

Many camera lenses are terrible when used visually.

a camera lens and eyepiece is a poor substitute for a good telescope.
Even a low priced long focus astro scope will completely outclass a camera lens and eyepiece.

Yes, top spotting scopes are expensive. Probably low volume items.
Some broadcast quality lenses are close to astro standard, but can cost $200,000.

B.

 

[moyang_mm]

Many camera lenses are terrible when used visually.

a camera lens and eyepiece is a poor substitute for a good telescope.
Even a low priced long focus astro scope will completely outclass a camera lens and eyepiece.

Yes, top spotting scopes are expensive. Probably low volume items.
Some broadcast quality lenses are close to astro standard, but can cost $200,000.

B.

Top spotting scope with DSLR digiscoping adapters is no substitute for good telephoto lens either. They are optimized differently.

The point is optically telescope is simpler than telephoto lenses. Were the market for scopes as competitive as the market for camera lenses, telescope should be cheaper than camera lenses.

 

[Patudo]

I think the "alpha" binoculars are very much overpriced due to the lack of economy of scale and the lack of competition.

I agree there is probably not a great deal of demand for "alpha" binoculars, but there seems to me that between the big three European manufacturers, Nikon, and a couple of other manufacturers (Kowa, Meopta, Canon) whose products could conceivably appear in the short list of individuals seeking a first class binocular, there seems to be pretty stiff competition for what demand there is.

I would also disagree that "alpha" binoculars are very much overpriced - it is beyond my budget to buy alpha binoculars new, but I would say the prices reflect what is needed for the design and manufacturing of top tier binoculars to be done in Europe and Japan. Their success in doing so can be seen by the fact that your earlier posts asked about Swarovski products rather than eg. Vortex.

 

[kimmik]

This was an interesting read and perhaps is worth revival and see if any new info came around. Some thoughts:

• Could premium binoculars be using ASPH without stating so? The swarobright thread clearly suggests many features go unadvertised
• ED glass and BAK4 and lanthanum glass are no longer advertised in isolation, too common and meaningless
• someone mentioned prismless inverted binoculars and longer binoculars. agree they will improve image quality, maybe it will be made as a novelty. I have this drawtube style 30x30 vintage binocular around F/15 focal ratio, works well for what it is.
• yes binoculars are overpriced just like art and diamond and swiss watches and anything else i cant afford 😂

 

[Binastro]

Certainly some camera lenses and telescopes were aspherised without any mention.

Zeiss were aspherising camera lenses in the 1930s using bought in machines which may have been 1920s.

The 1920 Zeiss 120cm f/7 Aero triplet (Cooke triplet) was probably hand aspherised.
They were so difficult to make that one element was split and later ones had four elements instead of three.

Some of the Dallmeyer Dallon (Booth telephoto) 36 inch f/6.3 aero lenses were hand aspherised, as they have excessive spherical aberration near full aperture.

Refracting telescopes were probably aspherised in the 1800s.
Of course mirror telescopes were aspheric in the 1700s.

It is quite possible binoculars have aspherics without mention.

However, designers really don't like aspherics, although they will use them if the market wants them.

They do result is shorter optics with less elements.

B.

 

[kimmik]

Certainly some camera lenses and telescopes were aspherised without any mention.

Zeiss were aspherising camera lenses in the 1930s using bought in machines which may have been 1920s.

The 1920 Zeiss 120cm f/7 Aero triplet (Cooke triplet) was probably hand aspherised.
They were so difficult to make that one element was split and later ones had four elements instead of three.

Some of the Dallmeyer Dallon (Booth telephoto) 36 inch f/6.3 aero lenses were hand aspherised, as they have excessive spherical aberration near full aperture.

Refracting telescopes were probably aspherised in the 1800s.
Of course mirror telescopes were aspheric in the 1700s.

It is quite possible binoculars have aspherics without mention.

However, designers really don't like aspherics, although they will use them if the market wants them.

They do result is shorter optics with less elements.

B.

One observation I wonder if you could offer an explanation, is how swaro EL has slightly wavy mustache type distorsion - is this a sign that asph lens is present? I can't explain how they can achieve edge to edge correction without ASPH when every other model just about, has edge blur.

 

[Binastro]

I have never looked through an EL, so cannot comment.

The low price Nikon Action VII and probably the Aculons have plastic aspherics stuck onto a glass eyepiece element.

There is a wavy effect of changing magnification as one moves across the field.
The field is relatively wide.

The early Minolta Rokkor 4 element short fast zoom lens had a stuck on aspheric.
Without it I think 6 elements would be needed.

I hate the view with the Russian 7x30 and 10x42 with six element, maybe seven element eyepieces.
It makes me seasick when I pan with them.
They are unlikely to use any aspherics.

If an EL is taken apart one can measure the curves to see if the elements are spherical or not.

Regards.
B.

 

[kimmik]

I have never looked through an EL, so cannot comment.

The low price Nikon Action VII and probably the Aculons have plastic aspherics stuck onto a glass eyepiece element.

There is a wavy effect of changing magnification as one moves across the field.
The field is relatively wide.

The early Minolta Rokkor 4 element short fast zoom lens had a stuck on aspheric.
Without it I think 6 elements would be needed.

I hate the view with the Russian 7x30 and 10x42 with six element, maybe seven element eyepieces.
It makes me seasick when I pan with them.
They are unlikely to use any aspherics.

If an EL is taken apart one can measure the curves to see if the elements are spherical or not.

Regards.
B.

If I find a broken EL, will kindly seek your help to take apart and measure.

 

[kimmik]

Where are the aspherics?

They are everywhere.

Unadvertised, unexplained, secretive.

But the results of the best aspheric designs, is in premium optics including binoculars.

We don’t even know how many ED elements there are in premium binoculars, we just know there has to be ED given how well CA is corrected.

We don’t know how many ASPH surfaces there are, but the wide and corrected to the edge designs clearly has them.

Why else isn’t china copying ZLS alphas? They have not got the skill, yet.

 

[kimmik]

This is the Sony 50mm macro f2.8, well regarded because of edge to edge correction, and documented to have aspheric front lens.



Now notice in the photo of front lens reflections, the wavy distortion of reflected straight lines.

 

[kimmik]

Now look at the eyepiece reflection of Nikon Monarch 7:



And EL:



To me this confirms aspheric surfaces at minimum in the eyepiece. We just dont know how many surfaces are aspheric. I can’t wait to find out!

 

[kimmik]

Found one swarovski product that explicitly mentions aspheric element:

25-50x W eyepiece

PRODUCT DESCRIPTION​

With the 25-50x wide-angle eyepiece, you can enjoy viewing comfort across the entire magnification range. With a weight of only 295 g / 10.4 oz and a unique optical system with an aspherical lens for an edge-to-edge viewing experience in sharp detail, this eyepiece is also excellent for digiscoping.

570pound list price. So this further confirms aspherics are in the wide angle eye-pieces of the premium binoculars, well within swaro technology to mass produce.

25-50x W - Swarovski Optik

www.swarovskioptik.com