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APO Summicron 50/2 ASPH: Central veiling flare / fogging


pajamies

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APO Summicron 50/2 ASPH: Central veiling flare / fogging

 

My brand new APO Summicron 50/2 ASPH produces flare / fogging under circumstances that should not cause problems, eg overcast sky, without any direct sunlight present.

Shading the lens with the hand from above removes the fogging.

 

Diglloyd.com has observed the same phenomenon, and suggests that inadequate blackening of the lens interior may be the culprit. Looking into the lens one can see two silvery rings that could reflect light.

 

Below is a photo of the rings taken with my iPhone.

 

 

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Guest borge

I've heard several people experiencing this on their brand new 50/2 APO's.

Seems like the issues that are present on the Summicron 50/2 non-APO is present on the APO as well.

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I would be really surprised to learn that the design of this one is anything other than meticulous in every aspect. This is the only report of this that I am aware of personally. I don't subscribe to the paid Digilloyd service myself though. There are very few of these lenses in customer's hands as we know. I can only comment from a handful of frames at a Leica boutique. Those were notably clean and sharp corner to corner.

 

I would check the fundamentals before assuming that the lens design is faulty.

Are the front and rear elements clean firstly? A fingerprint is the most common lens "fault".

 

It is possible to create flare with any lens in some circumstances (if you have direct non-image forming light across the front element for example). When you mention that shading that element with your hand stops the problem that suggests to me that may be the cause? I am only guessing from the information in your post.

 

Could you perhaps post or share some photos from the lens where you are seeing this fault?

Edited by hoppyman
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Thanks for your replies.

 

Firstly, photos taken with the sun behind me are awesome (a stevehuffianism there), eg. the last photo in the linked Dropbox file.

 

Secondly, no smears on either lens surface.

 

You asked for examples and here is a try, in no way rigorous enough to absolutely convince, but perhaps you get an idea of what I'm talking about.

 

In the linked Dropbox file, there is central fogging in the first photo, and fogging disappears with putting my hand above the lens as seen in the second photo. (The wind was strong but no flying sand).

 

The third photo has central fogging covering the foliage. The fourth was taken with the sun behind my back.

 

https://www.dropbox.com/sh/r1crwhyzn31ka8c/TmP9_sknOQ

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Isn't the point of this lens to *not* have a fingerprint? Said another way it should be fault free.

 

If one wanted a fingerprint one would buy the non-APO.

 

I think when he meant fingerprint, is a literal fingerprint where you finger touches the front or back element.

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I would check the fundamentals before assuming that the lens design is faulty.

 

I agree Geoff that we really don't have enough information to make any accusations at this point. Is this a one off anomaly? Could there be a design issue? Might a production process have been skipped? Impossible to know at this point.

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Firstly, if we want to have the ideal lens, we can draw it.

 

As that does not make sense, we have to accept a certain amount of imperfections.

In this case a lenshood could/should solve the problem.

 

I like to be underway with a small footprint (camera print).

I have to revise this aversion against lenshoods. That is difficult, because with a crop camera the regular lenshoods are not very effective.

 

Does there exist a standard object (a brick wall for the flare phenomenon) to compare lenses of different makes and/or samples of the same make?

Jan

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The key question for me is whether this is a "property" of the lens or the result of faulty production (ie. inadequate blackening of the lens interior).

 

In the first case one has to live with the restrictions for the use of the lens that this "property" brings. In the second case I should return the lens.

 

So which is it ?

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In the technical data - Leica supplies data according to MTF, distorsion, vignetting - but flare is not documented.

For what reason isn´t this mentioned?

Flare has not only to do with the design/realization of the optics, but also with the mechanical construction of the lens.

Jan

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One nice aspect of the live view on M240 is that one can see whats going on. Since we are blessed with sun in Bergen today, I entered the garden with the 50 APO on M240. With the sun in front and above the direction of the lens, the electonic VF reveals a quite distinct flare characteristics. To demonstrate this, a sequence of photos were taken, first with the lens pointing downward wrt to the sun and finally with the lens pointing towards the sun. The photos are shown below (f4, ISO 200, on tripod, no processing except reduced size).

 

The flare is clearly most prominent for the photo L...303. The flare is absent/weak for both larger and smaller incidence angles. For the shown setup, the critical flare angle (the angle between the direction of the lens and sun) is somewhere around 12 degrees. The last photo (L...311) shows the position of the sun.

 

The question remains, I guess, whether this flare is caused by reflection from internal mechanics or the configuration of the lens elements.

 

(for completeness: front and rear lens element are clean, no filter on lens, no hand-shading but the build-in lens shade was used).

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Edited by helged
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Pajamies this is an excellent contribution to the Forum and your provided files illustrate exactly what you have described. It was very useful to be able to eliminate the possibility of any external smear on the glass as well. I mentioned it because it is not the first time this has happened ;-)

 

While I always use my lenses with hoods, some of those are more effective than others too. It is always possible to create veiling flare with any lens in the right (wrong!) circumstance.

However your example in the third frame especially does not appear to be correct performance to my eyes with any modern Leica M lens.

I guess that your dealer could not offer you a replacement immediately due to the scarcity of the lens. Were the lens mine I would start with a conversation with Customer Service in Solms, including forwarding those examples to them.

I don't pretend to know what is the exact cause of the effect that you have shown with yours but I would think that Solms will (and should) work to correct this for you.

 

I hope that this is resolved speedily and to your satisfaction.

Good luck.

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APO Summicron 50/2 ASPH: Central veiling flare / fogging

 

My brand new APO Summicron 50/2 ASPH produces flare / fogging under circumstances that should not cause problems, eg overcast sky, without any direct sunlight present.

Shading the lens with the hand from above removes the fogging.

 

Diglloyd.com has observed the same phenomenon, and suggests that inadequate blackening of the lens interior may be the culprit. Looking into the lens one can see two silvery rings that could reflect light.

 

Below is a photo of the rings taken with my iPhone.

 

 

 

Pajamies, I was able to reproduce Lloyd Chambers' observations with my 50 AA on both M240 and M9. Chambers has concluded from additional testing that the lens hood is not fully sufficient on the 50 AA... when a strong light source from above the viewfinder horizon comes at the lens, the shade is not long enough to shield the front groups. If you look at your lens, you can easily deduce that the lens shade was substantially shortened as a stylistic issue. That is true for all of the Leica M 50's with built-in lens shades (and probably the 75, 90 and 135 as well). As you observe in your post, "Shading the lens with the hand from above removes the fogging."

 

Anyways, the 50 AA is just an incredible lens! ;) Just open it up to f/2 or f/2,8 and enjoy it!

 

Peter

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Having given my three day old APO 50 a bit of a work out I can't get

it to flair other than where you would expect any lens to do so.

As remarked above by Peter the little lens hood is a stubby unit,

probably it could have been a bit more utilitarian, but we can cope.

The lens is quite remarkable, it makes me wish I were a more talented

photographer.

Dee.

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Anyways, the 50 AA is just an incredible lens! ;)

 

The lens is quite remarkable

 

Agree! And in many cases a hand is sufficient to block for the sun when the rather short shade is insufficient to do the job. Actually, the lens is rather flare resistant when the sun points directly into the lens, which is quite remarkable. A small size, brilliant sharpness, high micro-detail, and smooth and pleasant out of focus rendering lens.

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Pajamies, I was able to reproduce Lloyd Chambers' observations with my 50 AA on both M240 and M9. Chambers has concluded from additional testing that the lens hood is not fully sufficient on the 50 AA... when a strong light source from above the viewfinder horizon comes at the lens, the shade is not long enough to shield the front groups. If you look at your lens, you can easily deduce that the lens shade was substantially shortened as a stylistic issue. That is true for all of the Leica M 50's with built-in lens shades (and probably the 75, 90 and 135 as well). As you observe in your post, "Shading the lens with the hand from above removes the fogging."

 

Anyways, the 50 AA is just an incredible lens! ;) Just open it up to f/2 or f/2,8 and enjoy it!

 

Peter

 

So it seems to be a property of the lens !

How unfortunate. It was my plan to have the 50 AA as my all around lens on my Leica M (instead of the bulky Noctilux). Now I'm hesitant.

Of course, I've only had the lens for three days, so we will see.

And as stated before, most of the shots are just awesome.

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