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Author Topic: Is this the normal bokeh for an L series lens  (Read 9465 times)

CharlieB

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Re: Is this the normal bokeh for an L series lens
« Reply #15 on: November 30, 2012, 11:47:05 PM »
I seem to recall something about wide aspheric lenses (or lens elements rather) doing the "disk effect" or "target effect".  Something to do with internal reflections from the non spherical element... I just spent a while looking for that... can't find it... but I "think" it was on one of the Leica web sites that caters to very high end testing of lenses.

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Re: Is this the normal bokeh for an L series lens
« Reply #15 on: November 30, 2012, 11:47:05 PM »

PackLight

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Re: Is this the normal bokeh for an L series lens
« Reply #16 on: November 30, 2012, 11:50:43 PM »
Thanks Packlight.  I just took the same image with my 85mm at 1.2 and the "onion skin" is present but to much less degree and not nearly as prominent.  It seems like the 35mm has this prominent target in the center of the onion that the 85mm does not have.  I am not sure if that is a lens characteristic or related to focal length or whatever else may be involved.  It is interesting that in another thread in the third party section titled "Sigma 35 f/1.4 DG HSM First Impressions" comparing the canon 35mm to the new sigma lens neither lens showed this characteristic (actually canon did a little) in the images shown.  Although it is only a small portion of the image shown 

http://lcap.tistory.com/entry/Sigma-35mm-f14-vs-Canon-35mm-f14-L

Blow up the picture the samples that say Bokeh Shape at f/1.4, you can see a few samples of it in that pic.
I just think it was the positioning of your tree and the exposure you used. I don't think you will notice this in 99% of the situations you shoot. But then I don't know what your subjects usually are.

EOBeav

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Re: Is this the normal bokeh for an L series lens
« Reply #17 on: November 30, 2012, 11:57:20 PM »
If this is normal, I am not impressed. Especially with the fringing..

You've got pretty high standards, then. I can just imagine the scenario: "Hey Mabel, will you come look at this? You can actually see the layers in the bokeh in our portraits! What was that photographer thinking when he bought that lens, anyway? Come here, look through this microscope, you can see it for yourself..."

Don't let this stuff get in the way of taking good photographs.
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Aglet

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Re: Is this the normal bokeh for an L series lens
« Reply #18 on: November 30, 2012, 11:58:25 PM »
seems like aspherical correction elements, wide apertures and certain focal distances can make the onion highlites show up.  Many lenses will do this, tho not always at all settings.
YMMV

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dirtcastle

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Re: Is this the normal bokeh for an L series lens
« Reply #19 on: December 01, 2012, 01:34:04 AM »
Ultimately, all lenses have limitations. And part of the challenge of photography is working around those limitations to get great shots. Big aperture lenses solve problems (low light, subject isolation), yes, but they also create new challenges (thin DOF, CA).

In this case, I'm sure we could come up with a dozen ways to avoid the undesirable effect. While I think we can all agree that it's frustrating to see those annoying effects. It's also a cool challenge. And occasionally, those shortcomings can be an unexpected benefit.


new day's resolution by Eric Nord, on Flickr
« Last Edit: December 01, 2012, 04:00:36 AM by dirtcastle »

Rat

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Re: Is this the normal bokeh for an L series lens
« Reply #20 on: December 01, 2012, 03:11:14 AM »
Great shot, dirtcastle. What I don't get is how the 'lemony' bokeh shape in the bottom come into being. Could anyone explain?
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Old Shooter

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Re: Is this the normal bokeh for an L series lens
« Reply #21 on: December 01, 2012, 03:28:12 AM »
Great shot, dirtcastle. What I don't get is how the 'lemony' bokeh shape in the bottom come into being. Could anyone explain?

I was just thinking the same thing!  :P
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Re: Is this the normal bokeh for an L series lens
« Reply #21 on: December 01, 2012, 03:28:12 AM »

eddiemrg

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Re: Is this the normal bokeh for an L series lens
« Reply #22 on: December 01, 2012, 03:58:38 AM »
Great shot, dirtcastle. What I don't get is how the 'lemony' bokeh shape in the bottom come into being. Could anyone explain?

I was just thinking the same thing!  :P

Probably becouse the surface reflect an "oval" beam of light!
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gmrza

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Re: Is this the normal bokeh for an L series lens
« Reply #23 on: December 01, 2012, 04:14:58 AM »
Here is another example that shows some of the aberrations that show up in the OOF blur, this time with the 100mm f/2.8L IS USM macro.
Zeiss Ikon Contax II, Sonnar 50mm f/2, Sonnar 135mm f/4

Rat

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Re: Is this the normal bokeh for an L series lens
« Reply #24 on: December 01, 2012, 04:48:12 AM »
Probably becouse the surface reflect an "oval" beam of light!
I don't think so. Some googling led me to this (very interesting) page, which says:
Quote
Sometimes what would be a circular out of focus highlight in the center of the image has a lemon shape outside of center, gradually more near borders and edges. This is caused by mechanical vignetting because the optical path in the lens is too narrow. Resulting shape is often a intersection of two non-concentric circles, often described as "lemon shape" or "cat eye".
But that immediately raises the question why even a classy lens like the 135L (which was used for this shot, according to the exif data) shows such 'defects'. I'm assuming this is a consequence of shooting wide open (tho I'm not sure), is it something to do with the ratio between distance and aperture? Anyone?
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Viggo

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Re: Is this the normal bokeh for an L series lens
« Reply #25 on: December 01, 2012, 06:11:31 AM »
Yes, it's normal! And yes the 35 has a CA issue. You're going to use it for portraits? Well... You really need to understand optics, the sooner you learn how crappy all lenses are, the better pictures you take ::) the 35 L is one of the absolutely greatest, I love it for the focal and that awesome AF, very sharp wide open. What makes me get the mk2 is primarily weather sealing, better corners and less ca.
« Last Edit: December 01, 2012, 06:15:05 AM by Viggo »
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jeffabbyben

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Re: Is this the normal bokeh for an L series lens
« Reply #26 on: December 01, 2012, 09:56:40 AM »
Viggo-thanks.  I realize that no lens is perfect and expected some CA as my 85mm also has this.  I am going to try some more shots in different situations but right now it looks like the bokeh would really bother me.  The central target  appearance in the center of the OOF light looks like eyes staring at me or a thousand nipples pointing at me :P

robbymack

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Re: Is this the normal bokeh for an L series lens
« Reply #27 on: December 01, 2012, 10:13:03 AM »
yes totally normal when shot wide open with a lot of contrast.  I find the need to look at bokeh at 100% pretty funny, only because no normal person does this, just the gear head.  Just about every lens will show these "onion rings" in various situations due to modern design including several elements of different sizes and shapes.  Essentially all you are seeing is the reflection of one piece of glass against the other.  That being said if you are unhappy with it return it and get another one.  I don't think that will totally solve the issue, but if it gives you more peace of mind so be it. 

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Re: Is this the normal bokeh for an L series lens
« Reply #27 on: December 01, 2012, 10:13:03 AM »

sanj

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Re: Is this the normal bokeh for an L series lens
« Reply #28 on: December 01, 2012, 10:47:21 AM »
If this is normal, I am not impressed. Especially with the fringing..

You've got pretty high standards, then. I can just imagine the scenario: "Hey Mabel, will you come look at this? You can actually see the layers in the bokeh in our portraits! What was that photographer thinking when he bought that lens, anyway? Come here, look through this microscope, you can see it for yourself..."

Don't let this stuff get in the way of taking good photographs.

Naaaa. I won't. I promise!

jeffabbyben

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Re: Is this the normal bokeh for an L series lens
« Reply #29 on: December 01, 2012, 11:20:30 AM »
RobbyMack-I do get your point about looking for bokeh at 100% but many times I print some of my images.  They're not works of art per se but I find I enjoy them more hanging on my wall for a few months at a time.  Sometimes I even print pretty large.  I also don't want to keep sending lenses back with unrealistic expectations.  Unfortunately where I live their is not a camera shop for 250 miles so I can't go try different copies or compare the new sigma.

« Last Edit: December 01, 2012, 01:01:53 PM by jeffabbyben »

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Re: Is this the normal bokeh for an L series lens
« Reply #29 on: December 01, 2012, 11:20:30 AM »