Aspherical Lenses: +/-

[rick123]

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Hi everyone,

 

As an avid amateur, I am confused about the benefit of an aspherical lens in a prime focal length. Is the main benefit of an aspherical lens in a wide-angle? Would someone kindly explain this to me. I remember hearing about a Puts article addressing the issue, but do not have a link. Thanks!

 

Rick

[robsteve]

Here is your link to Erwin Puts' lens compendium which talks about ashperics.

 

http://www.imx.nl/photosite/comments/paypal.html

[rick123]

Thanks so much Rob!

 

Rick

[j. borger]

What people tend to forget in the discussions about lenscorecttion and maximum resolution that a couple of non-aspherical lenses have a unique way of rendering (especially of people). A lenssignature typical Leica.

The 35 & 50 summilux pre-asph belong to this category: they have what people call the "old leica look".

The pre-asph lenses in general are also less contrasty .. which can be an advantage in certain shooting situations (sunny days) and for B&W.

Where the asph lenses really show their advantage is shooting wide open in low-light!

I use a combination of ASPH ans NON-ASPH lenses .... and often prefer the non-asph lenses (for pictures including people in B&W) because they show nicer tonality in B&W and are gentler to people.

[lars_bergquist]

What people tend to forget in the discussions about lenscorecttion and maximum resolution that a couple of non-aspherical lenses have a unique way of rendering (especially of people). A lenssignature typical Leica.

The 35 & 50 summilux pre-asph belong to this category: they have what people call the "old leica look".

The pre-asph lenses in general are also less contrasty .. which can be an advantage in certain shooting situations (sunny days) and for B&W.

Where the asph lenses really show their advantage is shooting wide open in low-light!

I use a combination of ASPH ans NON-ASPH lenses .... and often prefer the non-asph lenses (for pictures including people in B&W) because they show nicer tonality in B&W and are gentler to people.

 

What Berger says is actually that he often prefers lenses that are not quite sharp. But such lenses are NEVER quite sharp, even in situations where you wish they were. So,

get a sharp lens and a diffuser, and stop that nostalgic yammering!

 

The old badger from the Age of Uncoated Lenses

[j. borger]

What Berger says is actually that he often prefers lenses that are not quite sharp. But such lenses are NEVER quite sharp, even in situations where you wish they were. So,

get a sharp lens and a diffuser, and stop that nostalgic yammering!

 

The old badger from the Age of Uncoated Lenses

Borger is the name btw.....

and your interpretation is is NOT AT ALL what i am saying .......

Judging a lens on shapness alone shows a very limited view on what actually counts.

Especially if the lenses you are comparing are all "sharp enough" .... in most if not all situations! Different .. i said .. and often (NOT ALWAYS) more up to my PERSONAL liking!

[masjah]

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Rick

 

The advantages of aspherical lens elements are not confined to wide angles. The 90/2 Apo Aspherical (in both M and R formats) is an example. Aspherical technology is a tool in the lens designer's armoury, giving her/him greater power to "square the circle" of mutually irreconcilable design requirements (just as does anomolous dispersion glass, or other vitreous exotica).

 

I suspect that the different "look" of aspherical versus non-aspherical lenses is more a question of the age of the design, what is now or was then possible, and changing ideas of what a lens designer should be striving for.

 

I do agree with those who prefer the non-aspherical lenses for some portraits - though my experience is confined to the R system, and I take very few portraits indeed! But when I want to do a portrait at the 90 ish focal length, given the limited lenses I have available, I sometimes perversely use my 50/2 Summicron + 2X Apo Extender, in preference to the (nore ruthlessly analytical?) 90/2 AA.

[Peter Branch]

The 135mm f/3.4 Apo-Telyt-M has the current Leica signature - and how - but does not use aspheric technology. So it's more to do with current technological capability and design philosophy than the use of any particular technique such as aspheric surfaces. The modern lenses are different, no doubt about that, and you either like them or you don't. Personally I would always select one of the modern lenses because it does things the others can't, but you can always "soften" the images it produces if you want to.

 

Aspheric technology - according to Leica - enables them to build M lenses which are more compact than is possible by other means without sacrificing quality.

[j. borger]

Rick

I suspect that the different "look" of aspherical versus non-aspherical lenses is more a question of the age of the design, what is now or was then possible, and changing ideas of what a lens designer should be striving for.

That might be very true indeed .......

There are many people new to Leica M line of lenses here ..... just hope they think a bit broader than "latest and sharpest" ..... because that's a wonderful spinn off using a rangefinder: the broad choice of lenses ... sometimes very diferent from each other.

[rick123]

Thank you all for the kind explanations!

 

Rick

[fernando_b]

Aspherical lenses have at least one glass element with non spherical curved surface. Of course the designer choose to get non spherical the surface that mostly contributes to spherical aberration. Spherical aberration is an imaging error that (other things being equal) increases with lens aperture and equally affects all the field of view, even the central area. Other aberrations increase from centre to corners of the image. Supposing the spherical element is well mounted (as we expect from the expert manufacturing of our beloved brand) it is worth if a significant part of your images are at taken wide oper or near full aperture. If almost all your images are at f/5.6 or more closed you can choose a normal lens. This is what the theory says, real life is more complex than any scheme.

Fernando.

[wizard]

...But such lenses are NEVER quite sharp, even in situations where you wish they were. So,

get a sharp lens and a diffuser, and stop that nostalgic yammering!

 

Lars, with all due respect, as someone who is lucky enough to own both older Leica lenses (from e.g. the sixties) and their latest glass, I have to say your statement is NOT true. Take e.g. the Summicron 35mm 8-element lens, the Summicron 35mm 7-element lens, the Elmar 90mm 3-element lens and the Summicron 50mm 7-element lens (in both rigid and DR form) to name just a few, those lenses are amongst the sharpest Leica has ever produced, and in this regard are not surpassed by the latest designs. Where the new designs excel is contrast and image quality wide open.

 

Andy

[albertwang]

Lars, with all due respect, as someone who is lucky enough to own both older Leica lenses (from e.g. the sixties) and their latest glass, I have to say your statement is NOT true. Take e.g. the Summicron 35mm 8-element lens, the Summicron 35mm 7-element lens, the Elmar 90mm 3-element lens and the Summicron 50mm 7-element lens (in both rigid and DR form) to name just a few, those lenses are amongst the sharpest Leica has ever produced, and in this regard are not surpassed by the latest designs. Where the new designs excel is contrast and image quality wide open.

 

Andy

 

But isn't that perceived sharpness for those old lenses. Because the lens tests seem to bear out a higher resolution number for the newer lenses. I would suspect that the newer aspherics can separate the tonal range better than the older versions?

[peterv]

Interesting discussion...

 

I was thinking my first M-lens would be a 50 Lux ASPH.

 

now I can buy:

 

Leica Summilux 50mm/1.4

Leica Summicron 90mm/2.0

Leica Tele-ELmar 135mm/4.0

 

for appr. the same price.

 

What would you guys prefer? (and why?)

 

Would a 'softer' lens help in getting a 'non-digital' look? (If one would want such an effect...)

[georg]

That depends on your expectations.

 

When you want the highest image-quality possible with 35mm (chemical or digital) lenses like the 50Asph (or all new Leica-Asph) are simply superior in sharpness, contrast, color rendition, flare-resisance...

I own a 90AA since two years and shot it with 25ASA-B/W-film, Velvia or the M8 - I think I've never reached it's borders.

Most older lenses aren't bad either, but until you compare them to the new Asph you should be careful with telling that they are as sharp as it gets...

Regarding the price:

The 50Asph will propably be the best 50mm-lens the next 30 years - I think it's worth it.

 

Rent a 50Asph, shoot Velvia or Kodakchrome with it and look at them with a good loupe - I will never forget my first moment after photographing 25 years with Pentax...

 

But...

When you like a certain look, not technical perfection, dreamy bokeh (often caused by optical imperfections) you can take one of the older lenses an save a lot of money.

[kevin m]

So, get a sharp lens and a diffuser, and stop that nostalgic yammering!

 

Not the same thing. Diffusion generally looks like, well, you slapped a filter on your lens. Whereas a pre-asph. Summilux 50 is somehow sharp enough, yet kind to skin, and it doesn't look a bit 'fake.'

[wizard]

But isn't that perceived sharpness for those old lenses. Because the lens tests seem to bear out a higher resolution number for the newer lenses. I would suspect that the newer aspherics can separate the tonal range better than the older versions?

 

Well, it is sharpness perceived by myself, in large-format slide projection. To me that is all that counts. Also, I haven't seen lens tests supporting the conclusion that the newer lenses have higher resolution numbers. What the newer lenses have is more contrast, specifically at full or near full aperture.

 

Mind you, I am not saying that the older lenses are better than the current ones, but I strongly oppose the statement of older Leica lenses not being sharp, as many of them are about as sharp as it gets once they are stopped down to a certain extent.

 

Andy

[albertwang]

strongly oppose the statement of older Leica lenses not being sharp, as many of them are about as sharp as it gets once they are stopped down to a certain extent.

 

Andy

 

Yes but aren't we more concerned about wide open performance? That's the key. We like shooting portraits at f1.4

[kevin m]

Here's a straight-from-the-scanner image shot with a pre-aspherical 50 Summilux, wide-open, close focus on Fuji NPH. The only manipulation is 50% unsharp mask.

 

I don't want any more contrast than this in my people photography, and there's enough sharpness here to suit me. Dr. Mandler was no fool.

 

Please excuse the boring composition, but this was shot as a multi-lens test...

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Hallo,

Look here: Interesting Leica gear

[carstenw]

Well, it is sharpness perceived by myself, in large-format slide projection. To me that is all that counts. Also, I haven't seen lens tests supporting the conclusion that the newer lenses have higher resolution numbers. What the newer lenses have is more contrast, specifically at full or near full aperture.

 

The newer lenses often do have higher resolution, I believe. Anyway, this is rather irrelevant, and we must not forget that many of the older lenses were at the top of their respective categories in sharpness and contrast before the new ones came around. My favorite lens, the 80 Summilux-R, is incredibly sharp when stopped down, yet dreamy when wide open. Such a lens will never be "improved upon" by a sharper replacement, such as the Apo-Summicron-R 90 Asph. The new lens simply provides another option.