What does ASPH mean to you?

What does ASPH mean to you?

  • It's a better type of lens

    Votes: 11 14.1%

  • Marketing B.S. only

    Votes: 8 10.3%

  • 100% aspheric lens elements, no more spherical aberration or distortion for me!

    Votes: 10 12.8%

  • a small design tweak that *might* give a sharper image with less elements

    Votes: 49 62.8%
  • Total voters
    78
If it’s Leica asph, then it translates to being expensive. I know, I have a 50mm f1.4 asph. It’s a nice lens but it wasn’t cheap. Then again nothing is exactly cheap when you purchase Leica, but we know that and it’s nice.
If you can afford it why not. Shrouds don’t have pockets!
 
Freakscene said:
It is not due to the geometry of the lens. They are the result of marks on the aspherical element from the manufacturing process. They still appear in monochrome.



Most camera aspherical lens elements are manufactured by pressing hot liquid glass against a mould. The mould is a machined metal template with a curvature in the negative of the lens surface. The concentric patterns are traces of the turning process with which the moulds are manufactured. There are ways to both polish the mould and the elements to avoid this, but manufacturers typically don't employ them. The $US8k Leica 50mm Summicron ASPH APO has these concentric rings in the bokeh, and at that price point I'd have thought they would polish the mould better.

Marty
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Marty, what about some of the other ASPH Leica lenses? Are there some that are polished better? What about the 75mm Summilux or 75mm Summicron?
 
Rob-F said:
Marty, what about some of the other ASPH Leica lenses? Are there some that are polished better? What about the 75mm Summilux or 75mm Summicron?
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The 75 Summilux is all spherical, so no onion rings. The 75 Summicron has onion ring bokeh, but the geometry of longer lenses makes it somewhat less obvious. The only Leica ASPH lenses I have not tried are the 75 Nocti and the 90 Summilux - but from online photos you can see onion rings in the photos from these lenses too.

I use the 75 Summicron a lot, and the onion rings don’t bother me too much, but the way to avoid them 100% is to use older, all-spherical lenses.

Marty
 
Actually, I'm wondering how possible it is to polish an aspherical surface. I've seen photos of the equipment for grinding and polishing spherical lenses, and I can't imagine the same method working for an asphere, because the radius is not constant. I suppose there is some way, but I can see where the difficulty could be so great that it could be the reason why they don't always bother.
 
Rob-F said:
Actually, I'm wondering how possible it is to polish an aspherical surface. I've seen photos of the equipment for grinding and polishing spherical lenses, and I can't imagine the same method working for an asphere, because the radius is not constant. I suppose there is some way, but I can see where the difficulty could be so great that it could be the reason why they don't always bother.
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It's more that it is not economically viable rather than that it is not possible. But the available technology is changing, and the Sony lenses that have been recently introduced seem to have taken this into account.

Marty
 
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