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Is this CA problem on my 50/1.4 ASPH, it's normal or not?


Kasalux

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I got used Summilux-M 50 ASPH combine with Sony A7

 

but in my hand, Summilux 50 asph it easy to take the flare also purple CA (100% zoom no filter) follow image attached: F1.4

 

 

I just curious and ask anyone who own the Lux50 asph have problem above??? or this is normal?

 

PS. my Lux50 asph has oil mark on the aperture blade. ( TT___TT )

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Edited by Kasalux
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I have no experience with the 50/1.4 asph on Sony bodies but purple fringing can hardly be avoided around blown highlights, especially at full aperture. I would be more concerned about the oil marks on the aperture blades. Time to send the lens in i'm afraid.

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Kasa, for me it is more from the sensor * , that lens particularly

photo taken against the light and cropped. I do not have this problem with film

and with my Summilux 50 or 35 Asph!

Best

Henry

* normal for a sensor

secondary question : what is your memory card brand ?

Edited by Doc Henry
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Kasa, for me it is more from the sensor * , that lens particularly

photo taken against the light and cropped. I do not have this problem with film

and with my Summilux 50 or 35 Asph!

Best

Henry

* normal for a sensor

secondary question : what is your memory card brand ?

 

Thank you so much:D

 

 

What about M-digital camera? (I think have no problem, because it's compatible M-system)

 

secondary question : what is your memory card brand ?

- sandisk 16GB standard (I'll try to change Sonycard, that free together with A7 body)

 

 

not impressive!!!!

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Sorry, forgot to wish you welcome ! :)

 

Kasa I may have misspoken. :o I also have a 50 Summilux bought new I get on my 2 Leica digital and also two M film. On digital, it happens in the light conditions of wide gap exposure as your photos, to have this purple fringe for the reasons mentioned above.

CA can happen in these conditions but I think that not your lens.

I do not get that with the film because the dynamics of the film is better in these conditions.

Here is a picture 100% cropped taken "against the light" (contre-jour) with a 50 Summilux

 

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M7 50 LA

Kodak Portra 160

 

Grease on the blades do not affect the picture

Best

Henry

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Thank you so much:D

 

 

What about M-digital camera? (I think have no problem, because it's compatible M-system)

 

secondary question : what is your memory card brand ?

- sandisk 16GB standard (I'll try to change Sonycard, that free together with A7 body)

 

 

not impressive!!!!

 

Cards, camera brand, firmware, whatever, has little to nothing to do with this. As soon as a lens is capable of rendering high contrast edges, this problem will appear on any sensor.

Many sources attribute this problem to CA in the lens. However, I do not buy that. For one thing, the better the lens is corrected, the more chance that it is prone to purple fringing.

Secondly, if it were true CA, one would expect a green fringe on the contralateral side of the contrast edge (yes, I know about longitudinal CA). Furthermore one would expect the same effect on film, which not.

 

I am convinced that it is an interpolation artifact in in that the Bayer demosaicing gets disturbed by the contrast difference.

 

However, whatever the cause,as this is an universal problem, so almost all postprocessing programs have a slider to remove the fringe.

Simply use the tools in your Lightroom or Photoshop or C1 to remove this.

Edited by jaapv
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I had the same issue with my chrome 50 ASPH Summilux. Its purple fringing appeared on a lot of shots and together with the very stiff focus and razor sharp focus tab, encouraged me to sell it. I know a lot of folks say that the fringing is due to the very high edge contrast of this lens and on digital, you can't have one without the other. There are tools in most RAW developers to get rid of or at least reduce it. However my 50/2 Zeiss ZM Planar also has very high edge contrast and does not suffer purple fringing to anything like the same degree as the 50 ASPH Lux did. A friend had the same problem with a 35 FLE and has, as a result, reverted to the older 35 ASPH Summilux, so I do wonder if it has something to do with the light paths though the floating elements. OTOH my 50/.95 Noctilux, which also has floating elements, does not seem to suffer the problem to any noticeable degree, so maybe it is something else.

 

Wilson

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It usually is longitudinal CA, i.e. what is in front of the focus field is purple, what is behind is green (less noticeable). Well corrected APO lenses should not suffer from this issue.

 

In some cases, it may be caused by UV. There is an interesting discussion here:

UV 2A filter makes purple fringing go away: thank you Anders W!: Micro Four Thirds Talk Forum: Digital Photography Review

If that is the case, the lens transmission properties in the UV range, and the kind of UV filter on the sensor will make a difference.

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In some cases, it may be caused by UV. There is an interesting discussion here:

UV 2A filter makes purple fringing go away: thank you Anders W!: Micro Four Thirds Talk Forum: Digital Photography Review

If that is the case, the lens transmission properties in the UV range, and the kind of UV filter on the sensor will make a difference.

 

I was using my 50 ASPH Summilux on an M8 and would have been using a Leica UV/IR filter all the time, so the purple fringing I was getting was in spite of UV filtration. I sold it before getting my M9, so I don't know how it worked on that or my M240 for fringing without a UV/IR filter - worse or better?

 

Wilson

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the purple fringing I was getting was in spite of UV filtration.

 

Then it was most probably caused by longitudinal CA.

 

People who own both the 50 APO and the 50 Lux could be able to provide nice examples of cases like this. There should be a dramatic difference.

 

P.S. It is interesting to note that the 50 Lux is also an APO lens, according to this interview:

http://dfarkas.blogspot.com/2008/09/photokina-2008-day-2-taking-it-easy-and.html

But then again, the term APO is too generic to define the actual lens performance in cases like this.

Edited by CheshireCat
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But then again, the term APO is too generic to define the actual lens performance in cases like this.

 

I would think most modern Leica lenses would be APO corrected to a considerable degree. I am also not sure how you would define when a lens becomes defined as "APO" rather than Achromatic, for the degree of perfect convergence of all three prime colours. Maybe within a certain multiple of the median wavelengths along the optical axis.

 

I am not sure it is longitudinal CA, as I would have expected the Noctilux 0.95 to be worse than the 50 ASPH Summilux but in my experience it is better.

 

Wilson

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I am also not sure how you would define when a lens becomes defined as "APO" rather than Achromatic

 

The definition of APO is clear, but too generic to define the actual lens performance.

In nature, there are not just three primary colors but a full spectrum of infinite colors (light frequencies).

 

An Achromatic lens focuses two of these frequencies on the same plane, while an APO lens focuses three of them.

But the definition is too generic because:

- The spacing between these frequencies depends on the lens design. Some of these frequencies may even fall in the IR or UV range.

- There are no minimum-error requirements for all the other frequencies.

 

This means that two APO lenses may have very different performance from each other.

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I just curious and ask anyone who own the Lux50 asph have problem above??? or this is normal?

 

Normal ....... and this fringing is the same with virtually all fast lenses used wide open on digital sensors in situations where there is sharp edges with blown (or near blown) highlights adjacent.

 

From previous discussions I recall the consensus being that it is a mix of CA and sensor issues.... not purely just one or the other ......

 

Given the right conditions it can be truly awful and I am sure no lens is immune ....... and no sensor either .....but it can also produce some interesting images ...... this is the 50/1.4 inadvertently fairly wide open while taking a shot of the sea (cropped)... this is mostly the poor old sensor and the bayer matrix getting all confused by the sharp changes in illumination in adjacent cells .... :rolleyes:

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Edited by thighslapper
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Its a 'spurious' data effect of some sort - that is to say its an interpretation of data which does not represent the actual image formed on the sensor. I do not know anything about demosaicing, but I do know that at the limits of the sensor's ability to handle 'overexposure' the data becomes very unreliable. So, as these artifacts occur at the edges of areas 'correctly' recorded adjacent to those which are extremely overexposed, they represent some sort of inaccurate data which is itself created from accurate data and very inaccurate data.

 

I personally suspect that the problem is that when using a highly corrected lens, in areas of detailed and accurately exposed image adjacent to un-detailed, severe overexposure, the interaction is complex and whilst it is easy to blame CA this is a far too simplistic approach. I am far from convinced that it is attributable to CA. If it is then using a poor lens would reveal this problem too, even at smaller apertures when correction is not good, but in my experience this is not the case.

 

That said, I do await a definitive explanation (which may prove me wrong), but to date have not found one which sounds authoritative.

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I do await a definitive explanation (which may prove me wrong), but to date have not found one which sounds authoritative.

 

Sorry, I fail to understand your technical explanation :rolleyes:

 

In any case, I hope Erwin Putts is authoritative enough for you.

Read the last graph (and his explanation):

Apo-Summicron-M 2/50 mm ASPH, part 2 | The TAO of Leica

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In any case, I hope Erwin Putts is authoritative enough for you. Read the last graph (and his explanation):

Apo-Summicron-M 2/50 mm ASPH, part 2 | The TAO of Leica

No, it doesn't explain the variability of the often 'wide purple band' as far as I am concerned. As is all too often the case, I suspect that we have an interaction of various problems here but we tend to persist in trying to find a simplistic answer. Part of of the problem may be chromatic, but IMO only a part.

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