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Archive 2010 · Secretly aspherical lenses

Toothwalker
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p.2 #1 · p.2 #1 · Secretly aspherical lenses

Makten wrote:
I'm actually refering to wide-open shots with the 105/2.5. But if you can se "onion octagons" or any other shape than round, it should be proof for not being caused by an aspherical element.

Indeed. The mere fact that onion pentagons exist tells us that onion rings at full aperture are not necessarily due to the presence of aspherical elements. I cannot find the pentagons right now, but here is a complex pattern of
multiple ring structures within onion hexagons

Dec 20, 2010 at 04:00 PM

AhamB
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p.2 #2 · p.2 #2 · Secretly aspherical lenses

Toothwalker wrote:
Indeed. The mere fact that onion pentagons exist tells us that onion rings at full aperture are not necessarily due to the presence of aspherical elements.

When I compare the interference patterns seen in macro shots (I have never seen them in non-macro shots) with the onion rings seen in Luka's example, I think the ones caused by aspherics are easy to recognise.

Dec 20, 2010 at 04:28 PM

Maximilian
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p.2 #3 · p.2 #3 · Secretly aspherical lenses

This is not a guaranteed method of determining the presence of aspheres.

+1

Dec 20, 2010 at 05:04 PM

CheshireCat
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p.2 #4 · p.2 #4 · Secretly aspherical lenses

Seems to me that the Leica 35/1.4 Summilux ASPH has got a single spiral instead of multiple concentric rings !?

Dec 20, 2010 at 05:27 PM

NikkorAIS
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p.2 #5 · p.2 #5 · Secretly aspherical lenses

I have read and it has been reported that my Nikkor 300 2.0 IF-ED AIS and it's matched TC 14c converter contains at least one Asperical lens elements.

I can say that this 300 2.0 is sharper than it's 300 2.8 little brother. And the 1.4 converter rear element is a differnt shape than the TC-14 b .

with TC 14 c

Nikkor 300 2.0 IF-ED AIS on D3 ISO 500 handheld 1/200 second

Dec 20, 2010 at 05:32 PM

rsrsrs
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p.2 #6 · p.2 #6 · Secretly aspherical lenses

what a monster!

Dec 20, 2010 at 06:01 PM

Daniel Heineck
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p.2 #7 · p.2 #7 · Secretly aspherical lenses

....and my heart just did a major pitter patter. 300/2. I love it on principal. That's a lens high on my "win lottery indulgences"

Dec 20, 2010 at 06:44 PM

NikkorAIS
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p.2 #8 · p.2 #8 · Secretly aspherical lenses

3002.0/ 300 2.8/ 300 4.5

with TC-14c

with TC-301

Gregory

Dec 20, 2010 at 11:15 PM

jhapeman
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p.2 #9 · p.2 #9 · Secretly aspherical lenses

Toothwalker wrote:
More specifically ... such aspherics are one of several possible causes of onion rings.

Isn't the primary reason just basic physics? The "onion rings" are the Airy pattern, a function of diffraction, demonstrating the wave-like nature of light. I can't see why an aspheric vs. spheric surface would make a lick of difference here.

Jeff

Dec 20, 2010 at 11:24 PM

sebboh
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p.2 #10 · p.2 #10 · Secretly aspherical lenses

Daniel Heineck wrote:
....and my heart just did a major pitter patter. 300/2. I love it on principal. That's a lens high on my "win lottery indulgences"

i've always been curious to see if i could handhold it. for the price it goes for though i would probably rather just buy a noctilux and and have a FF camera custom made to mount it on.

Dec 20, 2010 at 11:54 PM

Daniel Heineck
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p.2 #11 · p.2 #11 · Secretly aspherical lenses

sebboh wrote:
i've always been curious to see if i could handhold it. for the price it goes for though i would probably rather just buy a noctilux and and have a FF camera custom made to mount it on.

For equivalent aperture, it's easier to handhold than a 600/4 because its shorter, but still a behemoth. Pretty much monopod or more territory.

A noctilux would make a lot more sense for my style of shooting as well. Love the normal perspective.

Dec 21, 2010 at 12:58 AM

IDURITA
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p.2 #12 · p.2 #12 · Secretly aspherical lenses

Sorry, I am not that skilled when it comes to those tech terms.

How about the Zuiko Auto--Zoom 35-80mm ED, it has a lot of special glasses.

On mir.com it says:

By using both Extra Low Dispersion glass and High Refractive Index glass lenses ...

Does it mean aspherical ?

Dec 21, 2010 at 01:16 AM

Daniel Heineck
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p.2 #13 · p.2 #13 · Secretly aspherical lenses

Not necessarily. Although lenses with a lot of good glass in it tend to also have aspherical lenses. They also tend to be really expensive.

Aspherically shaped elements are independent of the glass type.

Then again the kit lenses for most manufacturers could have an acrylic aspheric element in there for all I know.

Dec 21, 2010 at 01:24 AM

thrice
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p.2 #14 · p.2 #14 · Secretly aspherical lenses

sebboh wrote:
[you can see them in luka's example from the summilux (though they are much subtler than the from the zeiss), which dan said was hand ground as well. to my eye the pattern in that shot actually looks like a spiral rather than concentric rings. am i imagining it?

The ASPH is not hand ground. The ASPHERICAL is.

Dec 21, 2010 at 03:29 AM

thrice
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p.2 #15 · p.2 #15 · Secretly aspherical lenses

Maximilian wrote:
+1

Please explain how a distorted reflection off the lens element itself is not an indicator of aspherics?

Dec 21, 2010 at 03:31 AM

NikkorAIS
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p.2 #16 · p.2 #16 · Secretly aspherical lenses

Daniel your going hate me. And yes that is a Noct around my neck.

While it is possible to hand hold the Nikkor 300 2.0 IF-ED AIS it's about as ugly as hand holding the Nikkor 600 4.0 IF-ED.

Edited on Dec 22, 2010 at 12:04 PM · View previous versions

Dec 21, 2010 at 03:54 AM

thrice
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p.2 #17 · p.2 #17 · Secretly aspherical lenses

you seem overburdened, I will hold your noct for you while you use the bigger camera

Which noctilux is it?

Dec 21, 2010 at 04:01 AM

AhamB
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p.2 #18 · p.2 #18 · Secretly aspherical lenses

jhapeman wrote:
Isn't the primary reason just basic physics? The "onion rings" are the Airy pattern, a function of diffraction, demonstrating the wave-like nature of light. I can't see why an aspheric vs. spheric surface would make a lick of difference here.

Jeff

Jeff, the onion rings seen in denoir's shots will still be circular even when those lenses are stopped down and the highlights are no longer circular. In macro shots (like the ones Toothwalker linked to) the "onion rings" are hexagonal. Without knowing the physics behind it, I believe that "rings" in the airy pattern will be so closely spaced in Luka's shots that you can't discern them. What you're seeing are irregularities in the shape of the glass of an aspherical element. See page 32 on Dr. Nasse's article on bokeh and DOF:

If you look at this picture very closely, you can see another interesting effect – all the defocused spot images contain a circular structure. It is possible to recognise from this that the lens has an aspherical surface as these surfaces are often not as smooth as a conventionally polished lens. Particularly in the case of lenses which are manufactured by pressing hot liquid glass it is possible to recognise the traces of the turning process with which the mould was manufactured.
It is possible to combine rotational and pivotal movements when polishing spherical surfaces because the curvature of the surface is...Show more →

Dec 21, 2010 at 08:12 AM

sebboh
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p.2 #19 · p.2 #19 · Secretly aspherical lenses

thrice wrote:
The ASPH is not hand ground. The ASPHERICAL is.

ah, i always forget that there was an "aspherical" before the "asph", i think it's because i pronounce "asph" as aspherical.

do you know why the 35 lux asph seems to show spirals rather than rings in luka's shot?

Dec 21, 2010 at 11:15 AM

staticInc
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p.2 #20 · p.2 #20 · Secretly aspherical lenses

Have seen hexagonal "onion" rings with my Zuiko 28/3.5 with a 12mm tube in macro use. Am looking for the shots...
This would play in the field of those saying it is not necessarily caused by an asperical element. Or does the tiny Zuiko have an aspherical element?!?

Dec 21, 2010 at 11:23 AM

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