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-   -   What does ASPH mean to you? (http://www.rangefinderforum.com/forums/showthread.php?t=167559)

markbakovic 02-04-2019 05:02

What does ASPH mean to you?
 
I don't mean "Is the Leikor Bloktron 42mm 1.3 ASPH a good lens?", I mean what do you understand about "aspheric" *photographic* lenses? What are they for AFAYK? Are there pros and cons? What level of insight would you need to part with 2x the cash? 4x? Shut-up-and-take-my-money... umm... 'times'?

michaelwj 02-04-2019 05:10

It simply means that one surface of one element doesn’t have a single radius of curvature. As in, it’s not spherical.
As far as better? It usually means the lens designer can replace multiple elements with one element and therefore make a lens simpler and or smaller.
As for your poll, it’s is so misinformed that none of the choices make any sense. Is there a “none of the above”?

Ko.Fe. 02-04-2019 05:15

Since it is not posted in Leica Lens subforum.
CV ASPH lenses are not x2. 7A 28 f1.4 ASPH is less expensive than non ASPH CV 28 f2. And CV 35 f2 ASPH is less expensive than Biogon 35 f2 non ASPH.

It is shut-up-and-learn-before-posting "times". :).

Rayt 02-04-2019 05:41

Easier to design and produce lenses?

Rob-F 02-04-2019 05:53

I didn't see an option that reflects my understanding, either.

To me, the ASPH lens has the potential to perform better at the widest apertures. Stopped down to around f/8, not much difference. Or if there is one, the ASPH may render the image a bit sharper, but the image might look "harsh," less pleasing, depending on what I'm photographing. If I want to shoot at f/2 or f/2.8, I'll likely use a Summicron ASPH. At 5.6 or 8, I might use my Summaron or Zeiss c Biogon, or my non-ASPH Summilux. The latter is, IMHO, useless at f/1.4, but stopped down the images are just fine.

Apart from that, you have to go on a lens-by-lens basis. It's a matter of which lens, not ASPH vs. non-ASPH.

Ko.Fe. 02-04-2019 05:57

Forgot to mention, my new 35 2.5 ASPH Leica lens cost me less than averagely priced used and worn out Cron. It was one of the reasons I purchased it. :) .

Archlich 02-04-2019 06:09

The very basic Canon and Nikon 18-55 kit lenses both have an aspherical element. Your phone's lens has several. In fact it's rarer for you to see a spherical design than aspherical today, since the later has become so cheap to manufacture.

So the term does not guarantee anything but (mostly) marketing. Which in fact is a Leica (of which the path is followed by CV) specialty. Most of the Japanese manufacturers didn't even bother with it and other terms like FLE (in Nikon's literature, CRC) anymore after the 1980s', during which these technologies became widespread. They've got more posh words to play with now.

kyte 02-04-2019 06:14

To me it means a computer designed lens that has modern characteristics, not necessarily meaning better.

lawrence 02-04-2019 06:16

Quote:

Originally Posted by Rob-F (Post 2866829)
To me, the ASPH lens has the potential to perform better at the widest apertures.

Yes, that plus you tend to swap some barrel distortion for pincushion.

markbakovic 02-04-2019 07:18

well that was... bracing.

Thank you to the honest respondents to a poll about what camera equipment consumers glean from camera equipment manufacturers' branding.

To the others, thank you for offering your opinions as well.

I look forward to learning more of what readers of the Optics Theory subforum have to say on this topic.

Mackinaw 02-04-2019 08:06

My experience? Aspherical surface usually means a sharper, more contrasty image wide-open, especially with a high-speed lens. Comparing an ancient Canon FD 55/1.2mm with a FD 55/1.2 aspherical wide-open, the difference is dramatic, with the aspherical being much better. Of course many will argue that the signature of the non-aspheric is better. But that’s a personal choice.

Jim B.

bayernfan 02-04-2019 08:08

If the element count is kept low, an aspherical lens can offer nice correction and wide open performance without that clinical/flat look. I think the Summicron 35/2 ASPH is an example of this, in that it has some 'character' despite the aspherical element.

David Hughes 02-04-2019 08:10

In some cameras it means a plastic lens. Those I've seen were no better and no worse than normal lenses. OTOH I've been very pleased with "proper" glass ones in various lenses.

I won't mention the technical bit as it's been covered.

Regards, David

willie_901 02-04-2019 08:27

ASPH is one of several optical designs purposed to minimize spherical aberration artifacts. The primary symptom is haloing caused by light ray refraction differences between the edges and centers of spherical lens elements. It is impossible to focus the rays to a single point.

The refraction artifacts decrease as aperture decreases since the lens edges become blocked.

Spherical aberration is also associated with focus shift.

Some very fast ASPH lenses have magenta color casts for foreground out of focus objects and green casts for those in the background (spherochromatism). The optical refraction compensation is not the same for all wave lengths. This is different than chromatic aberration.

raid 02-04-2019 09:10

ASPH ==> extra cost.

aizan 02-04-2019 09:30

It usually means onion-ring bokeh to me.

Phil_F_NM 02-04-2019 09:57

It usually means expensive, harsh and boring to me.
Phil Forrest

nightfly 02-04-2019 12:22

It means it will be several times the price of the older iteration of the same lense which will henceforth become known as the "non-ASPH" version.

pgk 02-04-2019 13:47

Aspherical lens surfaces are used in all sorts of applications, some expensive, some not. Most are now molded but in the past they were ground which was far more expensive. They have advantages for the design and build of lenses in terms of optical improvements, size, simplicity and so on. The poll is far too simplistic to have any value.

michaelwj 02-04-2019 15:03

Quote:

Originally Posted by markbakovic (Post 2866855)
well that was... bracing.

Thank you to the honest respondents to a poll about what camera equipment consumers glean from camera equipment manufacturers' branding.

To the others, thank you for offering your opinions as well.

I look forward to learning more of what readers of the Optics Theory subforum have to say on this topic.

"ASPH" or "Aspherical" on a lens denotes it contains an aspherical surface. You can't just brand a lens as such without an aspherical surface (you can I suppose, but it'd be lying). It used to be a big deal, but now it isn't. You phone most likely has the most aspherical lens you've ever used, yet it doesn't mention it, and doesn't conform with many of the above perceptions of what aspherical surfaces have on image quality.

zuiko85 02-04-2019 15:38

Meh.
Even some single or doublet molded plastic lenses on simple cameras can have aspheric surfaces. You can tell by the way the surface reflects light.

Darthfeeble 02-04-2019 15:53

You should include the choice for "I have no idea really".

Dan Daniel 02-04-2019 15:58

I've always enjoyed this "Tessar" from a Nokia phone. Hard to believe it can even make an image, but I guess those aspherical elements do some kind of magic. I wonder if there is even one true spherical surface, even for brief sections of an element-



Sumarongi 02-04-2019 15:59

hmmm, it's an acronym?

Perhaps:

A Serious Photographic Hoax

:D

Scottboarding 02-04-2019 18:21

Not spherical is generally what comes to mind :D

Ko.Fe. 02-04-2019 18:41

Ultron 28 1.9 ASPH. Smaller than previously owned 28 2.8 III Elmarit-M. Less expensive as well.
It is not as good as Elmarit-M on darkroom prints, but not flat.
On digital M it is smooth lens. Some are saying it is as good as Summicron 35 f2 ASPH.
Most of my "Hamilton as i know it" color shots were taking with this lens.

Ultron 35 1.7 LTM. This lens was better lens than CS 35 2.5 on prints.
No harsh contrast and it was not flat rending lens at all.
They say VM version of this lens is better comparing to Leica and Zeiss.
I think, it is possible to add focus tab to LTM version. With this it is best 35 RF lens for price and performance. For darkroom prints. IMO.

Nokton 50 1.5 VM. Great lens on prints and on BW digital. More alive lens comparing to sterile Planar ZM, Cron Rigid and IV in BW.

Summarit-M 35 2.5 ASPH - best lens I ever owned and have negatives to print from.
Even better than 35 1.7 Ultron LTM I owned before it. It is not about distortion free and such, which this lens isn't great, but very pleasing rendering of small details, edges and contrast on darkroom prints. It simply gives more on the print, but nothing too sharp.
I'm not using it much on digital M, camera I not using much in general. But it is very good, nothing retro or clinical.

xmas_one 02-04-2019 20:04

https://en.m.wikipedia.org/wiki/Aspheric_lens

jarski 02-04-2019 21:16

Now, what is APO then, in layman's terms? :)

bayernfan 02-04-2019 21:53

Quote:

Originally Posted by jarski (Post 2867019)
Now, what is APO then, in layman's terms? :)

it makes the red, blue and green lines play real nice with each other.

Rob-F 02-05-2019 02:08

Quote:

Originally Posted by jarski (Post 2867019)
Now, what is APO then, in layman's terms? :)

The full term is "apochromatic." It means that the three primary colors, red, green and blue, all come to a focus in the same plane. A non-APO lens might typically bring only two of three primaries (such as blue and green) into sharp focus at the film or sensor plane.

Freakscene 02-05-2019 14:56

Quote:

Originally Posted by markbakovic (Post 2866791)
What does ASPH mean to you?

Like Vienna it means nothing to me.

It strictly means that one or more of the lens element surfaces are, as pointed out, made with multiple radii of curvature.

Quote:

Originally Posted by aizan (Post 2866902)
It usually means onion-ring bokeh to me.

This is annoying. There are methods to polish elements to avoid this, but lens manufacturers typically don't employ them.


This is from a 35 Summilux ASPH (the pre-FLE one). Annoying, it looks weird.

Quote:

Originally Posted by Rob-F (Post 2867046)
The full term is "apochromatic." It means that the three primary colors, red, green and blue, all come to a focus in the same plane. A non-APO lens might typically bring only two of three primaries (such as blue and green) into sharp focus at the film or sensor plane.

Technically correct, but often used as marketing nonsense, because none of the camera lenses available today are really apochromatic. Microscope and technical lenses are another story.

We should all stop worrying. Go out and take some photos (ASPH lens or not, whatever you like), and show us.

Marty

michaelwj 02-05-2019 15:58

Quote:

Originally Posted by jarski (Post 2867019)
Now, what is APO then, in layman's terms? :)

In X-ray microscopy (my field) we have two (main) ways to focus X-rays.
The first is a Fresnel Zone Plate, which is a refractive lens. The focal length is a function of the X-ray wavelength, f=(2r*delta(r))/wavelength. So as the wavelength increases, the focal length decreases: It is a chromatic focus.
The second is a Kirkpatrick-Baez mirror pair. The focus here is dependent on the curvature of the mirror, and the wavelength does not figure into the calculations. You can change the wavelength and it does not change the focal length. It is a true achromatic.

In camera lenses, achromatic was first used as an approximation of a true achromatic lens (they converge two wavelengths). Apochromatic was invented for photography (it's not a true scientific word), to distinguish lenses that did a better job than the original achromatic lenses did (they converge three wavelengths). Interestingly, you might think that the three wavelengths would be red, green, and blue, but it doesn't have to be the case, they can include IR or UV (telescopes often include IR for example). Given the looseness the term APO is used in photography, I wouldn't be surprised if this applied to photographic lenses too.

markbakovic 02-06-2019 01:59

Quote:

Originally Posted by Freakscene (Post 2867211)
This is annoying. There are methods to polish elements to avoid this, but lens manufacturers typically don't employ them.


This is from a 35 Summilux ASPH (the pre-FLE one). Annoying, it looks weird.

that looks a bit like cavity resonance to me a la Fabry-Perot, like a surface pair is locally close to plane parallel. If so that might be unavoidable with the geometry in question. (I say this in part because the image looks near-monochromatic: does it still do it with white, with no colour fringing "in the onion rings"?).

If you mean the method of "machining" aspheric surfaces with a diamond stylus and then not smoothing the grooves, I guess this is one way to avoid too much cost increase: if you look at optic catalogues and the same-size, same-glass, same-EFL, same-surface tolerance precision asphere is 2-5x the price of the corresponding spherical item that input cost has to either be passed on to the consumer or reduced somehow. I guess it boils down to microfacets left on glass or moulded plastic (at least index matched caps) or less money spent elsewhere (or price hike).

Quote:

Originally Posted by jarski (Post 2867019)
Now, what is APO then, in layman's terms?

I see what you did there ;)

To be fair though I don't think you could really get away with designing a lens with, say violet, red and like 740nm or so (which might be reliably picked up by most IR films) brought to the same focus but a huge excursion peaking at 500nm, call it APO and rake in the dollars. But yeah, the similarity in terms of marketing the method rather than the results is... uh... hard to overlook :)

Once again: I'm not talking about specific lenses which are or are not marketed as ASPH, APO or anything. I'm not insulting your decision to use, or not use any lens so marketed or opinions of same. I'm talking about what, if anything, that marketing implies to you as a consumer. Most of the responses so far have been useful, illustrative and/or entertaining.

pgk 02-06-2019 04:11

Quote:

Originally Posted by markbakovic (Post 2867299)
I'm talking about what, if anything, that marketing implies to you as a consumer.

The simplest implication is that the design is relatively new and that the lens has been designed with an aspherical surface to improve it in some way (I know that this might mean improve its marketability) so that its performance should be improved or there is another advantage gained (size, weight, production cost, etc.). Like any other 'designation' aspherical/aspheric/asph. is something which appeared as designs took advantage of such surfaces, mostly to differentiate them from older ones, but which has inevitably become something used to try to drive sales. It's interesting that Leica did not immediately use the designation on their more recent Summarit range, almost as though it is now becoming just another tool in their optical designer's options. Perhaps it's now moving away from being a new marketing tool and into the normality of lens design.

ph. 02-06-2019 06:02

My first associative response was to recall the ancient Kilfitt 90mm macro which had an element with two radii.

My second was to recall the last LeicaR 35-70 which had a "secret" aspherical element in the sense that no advertising bothered to mention it.

In the first case concentric rings can be observed, in the second, no particular peculiarities.

p.

Ted Striker 02-06-2019 06:18

Quote:

Originally Posted by Archlich (Post 2866835)
The very basic Canon and Nikon 18-55 kit lenses both have an aspherical element. Your phone's lens has several. In fact it's rarer for you to see a spherical design than aspherical today, since the later has become so cheap to manufacture.

So the term does not guarantee anything but (mostly) marketing. Which in fact is a Leica (of which the path is followed by CV) specialty. Most of the Japanese manufacturers didn't even bother with it and other terms like FLE (in Nikon's literature, CRC) anymore after the 1980s', during which these technologies became widespread. They've got more posh words to play with now.

That's not true at all. Fujifilm camera lenses have the word "Aspherical" stamped all over them and Canon and Nikon literature prominently highlight the presence of any aspherical elements in their lens designs.

David Hughes 02-06-2019 07:28

While you are all here can I ask if the advent of optical grade plastic meant that a lot of glass compound lenses were replaced by one plastic lens?

I'm thinking of the triplets that look remarkably like the "4 in 3" glass Tessar.

Regards, David

Bill Clark 02-06-2019 08:11

Quote:

What does ASPH mean to you?
No meaning for me.

Lot of marketing/sales used to justify higher prices.

Maybe the most help with wide angle lenses.

But my Nikkor 20 I bought in 1972 works just fine for me, when I need it, rarely. It’s not ASPH.

Interesting article of injction molded plastic lenses:

https://www.lenseloptics.com/plastic-optics/

Taiwan manufacturer:

https://asia.nikkei.com/Companies/LA...cision-Co.-Ltd

steveyork 02-06-2019 09:07

The aspherical lenses I have used (Leica and Voigtlander) have all been very sharp and clinical. Great, I suppose, for color film, but I find them a bit jarring for B&W film.

markbakovic 02-06-2019 13:14

Quote:

Originally Posted by David Hughes (Post 2867342)
While you are all here can I ask if the advent of optical grade plastic meant that a lot of glass compound lenses were replaced by one plastic lens?

I'm thinking of the triplets that look remarkably like the "4 in 3" glass Tessar.

Regards, David

It'd still have to be two different plastics to have two different refractive indices, but if, say, the original cemented pair was two glasses with (probably high) dispersion characteristics that together (nearly) cancelled some other part of the system; that might be replaced by a single lens of a similarly dispersive material (which some plastics probably are). After all the Tessar is a modified triplet so you may well be right AFAIK.


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