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Voightlander Lenses, LoCa and Purple Fringing


paulcurtis

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Not on the UV end in my experience. I did a bit on the M8 years ago and it turned out quite well - I'll see if I can dig out my filter and try the M9 out. AFAIK the M sensors are not UV filtered, and my Summarit 50/1.5 certainly is not.

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The M9 and M Monochrom using BG-55 glass, which replaced S8612, are quite sensitive in the UV region. I use a lot of older lenses. The Red dye used on the M9 has a large uptick in sensitivity in the UV region.

https://shop.schott.com/medias/schott-bandpass-bg55-jun-2017-en.pdf?context=bWFzdGVyfHJvb3R8Nzk4MDAyfGFwcGxpY2F0aW9uL3BkZnxoYjAvaGU1Lzg4MjAyMzQxOTA4NzgucGRmfDVmNjE3ZTMyZGIzZTUwM2FkNDI1NDI3OTdhMzhjMTI2NGYwMGVkMDA5Mjg4ODI1M2ZhOThjN2U2NTIyYjRjODM

On the prior discussion- there are two types of chromatic aberration. From Wikipedia- "Transverse aberration occurs when different wavelengths are focused at different positions in the focal plane, because the magnification and/or distortion of the lens also varies with wavelength." This is easy to correct for a color digital camera using Post Processing.

From Wikipedia- "axial (longitudinal), and transverse (lateral). Axial aberration occurs when different wavelengths of light are focused at different distances from the lens (focus shift)." This type is difficult to correct for color cameras in post processing. Both types of chromatic aberration can be reduced by using a color contrast filter on monochrome cameras or with B&W film. This is why the specific type of chromatic aberration produced by a lens is important to know. My 1934 5cm F2 Sonnar is very sharp on the M Monochrom using an Orange filter.

 

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I searched more on the net, and it appears - in addiction to what you two are saying - that the M9 may not have a (dichroic) UV & IR sharp cutting filter that Kolari Vision says is fused on the sensor. Their competitors / colleagues at MaxMax also has a graph (see link below) showing the transmission of the filter they removed from a M9, and they say that it ought to have a dichroic UV/IR cut filter on it, but there is no such filter. This (according to MaxMax) is the reason why the sensor glass has corroded in M9 cameras. In other words, Leica used glass that will corrode (by oxidation), but didn't cover the surface... Ouch!

Most digital cameras have both a dichroic sharp UV/IR cutting filter and a greenish-blue IR absorbing filter which in combination effectively cuts away both UV and IR and optimizes the light transmission to the sensor. Given there is no dichroic UV/IR cut filter in the M9 (and even newer M cameras), it makes sense to use UV/IR cut filters like those from Hoya and B+W on the lens. That said, these filters will cause color shift outside the center on wide angle lenses, so just using Zeiss T* UV cut filters seems like the best option there.

The above conclusions are actually encouraging to me, since this means that my Kolari Ultra-Thin converted Z6 will have the same properties as a digital Leica M camera.

https://maxmax.com/faq/camera-tech/leica-m9-corrosion

Edited by LarsHP
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12 minutes ago, LarsHP said:

I searched more on the net, and it appears - in addiction to what you two are saying - that the M9 may not have a (dichroic) UV & IR sharp cutting filter that Kolari Vision says is fused on the sensor. Their competitors / colleagues at MaxMax also has a graph (see link below) showing the transmission of the filter they removed from a M9, and they say that it ought to have a dichroic UV/IR cut filter on it, but there is no such filter. This (according to MaxMax) is the reason why the sensor glass has corroded in M9 cameras. In other words, Leica used glass that will corrode (by oxidation), but didn't cover the surface... Ouch!

Most digital cameras have both a dichroic sharp UV/IR cutting filter and a greenish-blue IR absorbing filter which in combination effectively cuts away both UV and IR and optimizes the light transmission to the sensor. Given there is no dichroic UV/IR cut filter in the M9 (and even newer M cameras), it makes sense to use UV/IR cut filters like those from Hoya and B+W on the lens. That said, these filters will cause color shift outside the center on wide angle lenses, so just using Zeiss T* UV cut filters seems like the best option there.

The above conclusions are actually encouraging to me, since this means that my Kolari Ultra-Thin converted Z6 will have the same properties as a digital Leica M camera.

https://maxmax.com/faq/camera-tech/leica-m9-corrosion

I would just add that other modern sensors may or may not be fully cutting IR/UV as we expect them to — for example, I’ve never seen a test of the R5/6 for IR or UV leakage. I do see minor improvements on the R/R5/R6 with the UV/IR cut filter (in this case the L2 sensor filter by Astronomik) when shooting at MFD with a lens known to have CA or haze wide open at MFD such as the RF 15-35 at 35mm and f/2.8 at MFD. Anyway, I don’t think the improvements are large enough to warrant buying UV/IR cut or Zeiss T* UV for all your lenses, but if you need the environmental protection and will be buying a protective filter anyway, it may be something to consider. And if so, I would say UV/IR cut for lenses that struggle at MFD due to CA and UV for everything else. Biggest reason to go Zeiss T* UV is because in my experience they and the Leica UV filters have been the only ones to not reduce infinity performance for lenses known to have issues when filtered such as telephotos (in my case the RF 100-500).

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The Leica M9 used S8612 cover glass that was coated on both sides and sealed. The problem was the seal broke down and moisture caused corrosion.

Leica replaced the S8612 cover glass with Schott BG-55, also coated on both surfaces.

 

The S8612 and BG-55 are very efficient at absorbing IR. The CCD array used was produced by Kodak, most of their CCD's were used for scientific applications. The UV sensitivity is higher than most consumer-grade digital cameras. 

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1 hour ago, steve 1959 said:

The real subliminal message on this thread is that voigtlander lenses are rubbish so do not waste your money but buy five times more expensive lenses from leica that have no "loca" at all.

I can hardly tell the difference between loca and laca (is it that?) but i can recognize purple fringing when i see it and my CV lenses are sometimes more, sometimes less prone to it than my Leica ones with no obvious winner.  

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47 minutes ago, lct said:

I can hardly tell the difference between loca and laca (is it that?) but i can recognize purple fringing when i see it and my CV lenses are sometimes more, sometimes less prone to it than my Leica ones with no obvious winner.  

I know

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This thread diverged but in an interesting direction. I have many cameras so see many different interactions and i guess this highlights how many different elements there are in a chain to sensor that will affect everything. An awful lot of cinema cameras tend to be overly sensitive in IR, perhaps in an attempt to boost sensitivity at that red end of the sensor and results in a whole range of Hot ND filters, which both ND and IR cut because black materials change colour in footage due to IR emission/pollution.

The source spark was would a UV filter tame purple fringing and i guess the answer is 'it depends' on the whole chain to sensor, lens, filters etc,. Certainly next time i do a lens test i will include this to see. I have a feeling it probably wouldn't too much. At least with CMOS we don't get the same kind of CCD smear with overcharging of the sensor wells!

9 hours ago, lct said:

I can hardly tell the difference between loca and laca (is it that?) but i can recognize purple fringing when i see it and my CV lenses are sometimes more, sometimes less prone to it than my Leica ones with no obvious winner.  

I guess it depends how sensitive you are to it. My point simply is that in motion, with focusing then the whole image shifting colour in high contrast areas is a massively obvious thing. Therefore it is of importance to me. I see this a lot in peoples tests. And at the same time whilst PF and other elements are fairly easy to minimise in a still, when you are dealing with 10s or 100s of thousands of frames then it is an issue. Also if you have to work with the footage in post - whether it be keying green screens/roto or even doing the opposite where you have to add aberrations to CG footage to help match plates - these issues become way more important. That's my crux with this whole thing.

 

8 hours ago, steve 1959 said:

I know

You must be a glutton for punishment following this thread :)

But if you can't tell or it doesn't pop up on your radar then you can make you choices based on your preferences

cheers
Paul

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8 minutes ago, paulcurtis said:

I guess it depends how sensitive you are to it. My point simply is that in motion, with focusing then the whole image shifting colour in high contrast areas is a massively obvious thing. Therefore it is of importance to me. I see this a lot in peoples tests. And at the same time whilst PF and other elements are fairly easy to minimise in a still, when you are dealing with 10s or 100s of thousands of frames then it is an issue. Also if you have to work with the footage in post - whether it be keying green screens/roto or even doing the opposite where you have to add aberrations to CG footage to help match plates - these issues become way more important. That's my crux with this whole thing.

I can understand that (i did not say all that :D) but what is your conclusion as far as Leica cameras or lenses are concerned if i may ask?

Edited by lct
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14 hours ago, hdmesa said:

I would just add that other modern sensors may or may not be fully cutting IR/UV as we expect them to — for example, I’ve never seen a test of the R5/6 for IR or UV leakage. I do see minor improvements on the R/R5/R6 with the UV/IR cut filter (in this case the L2 sensor filter by Astronomik) when shooting at MFD with a lens known to have CA or haze wide open at MFD such as the RF 15-35 at 35mm and f/2.8 at MFD. Anyway, I don’t think the improvements are large enough to warrant buying UV/IR cut or Zeiss T* UV for all your lenses, but if you need the environmental protection and will be buying a protective filter anyway, it may be something to consider. And if so, I would say UV/IR cut for lenses that struggle at MFD due to CA and UV for everything else. Biggest reason to go Zeiss T* UV is because in my experience they and the Leica UV filters have been the only ones to not reduce infinity performance for lenses known to have issues when filtered such as telephotos (in my case the RF 100-500).

I feel confident that the Canon R series cameras have cut away practically all UV and IR in their sensor glass. The question then is why you see an improvement when adding the Astronomik L2 UV/IR cut filter... That's beyond my knowledge, but my guess would be that when the angle of light gets high enough, these dichroic filters starts cutting in the visual range and this could "help" the performance of the lens. Regarding UV and protection filters on telephoto lenses, my understanding is that this is about the quality of glass and how flat it is. These things get magnified on (long) telephoto lenses.

13 hours ago, BrianS said:

The Leica M9 used S8612 cover glass that was coated on both sides and sealed. The problem was the seal broke down and moisture caused corrosion.

Leica replaced the S8612 cover glass with Schott BG-55, also coated on both surfaces.

 

The S8612 and BG-55 are very efficient at absorbing IR. The CCD array used was produced by Kodak, most of their CCD's were used for scientific applications. The UV sensitivity is higher than most consumer-grade digital cameras. 

The S8612 is known as the best IR cutting filter for stacking with UV pass filters. It cuts heavily in the red end and not much in the violet. However, thickness is paramount when talking about how well it (and other absorptive filters) suppresses IR. For UV photography it's minimum 1.5mm (usually 2mm is recommended), but that will be cutting red too much for visual, so Leica most likely have used a thinner filter, maybe 0.8 or so. (This guess is based on how thick the M9 sensor filter is measured to be.) This also means that a thin S8612 filter will be extremely transparent to UV. To be honest, I am a little skeptical that Leica wouldn't add some kind of UV cut to their filter stack, but this may be the case nonetheless.

13 hours ago, steve 1959 said:

The real subliminal message on this thread is that voigtlander lenses are rubbish so do not waste your money but buy five times more expensive lenses from leica that have no "loca" at all.

Well, that's not my stance at least. My impression is that the newer Voigtländer lenses have been fantastic. Leica and Voigtländer may have different priorities regarding lens design compromises though. My Nokton 50mm f/1.2 Asph VM is just lovely in almost every way, but LoCA is not a strong point at wide apertures.

11 hours ago, lct said:

I can hardly tell the difference between loca and laca (is it that?) but i can recognize purple fringing when i see it and my CV lenses are sometimes more, sometimes less prone to it than my Leica ones with no obvious winner.  

LoCA = longitudinal chromatic aberration.

LaCA = lateral chromatic aberration

Here is a good explanation (with graphics and sample images) : https://photographylife.com/what-is-chromatic-aberration

Edited by LarsHP
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46 minutes ago, LarsHP said:

I feel confident that the Canon R series cameras have cut away practically all UV and IR in their sensor glass. The question then is why you see an improvement when adding the Astronomik L2 UV/IR cut filter... That's beyond my knowledge, but my guess would be that when the angle of light gets high enough, these dichroic filters starts cutting in the visual range and this could "help" the performance of the lens. Regarding UV and protection filters on telephoto lenses, my understanding is that this is about the quality of glass and how flat it is. These things get magnified on (long) telephoto lenses.

The S8612 is known as the best IR cutting filter for stacking with UV pass filters. It cuts heavily in the red end and not much in the violet. However, thickness is paramount when talking about how well it (and other absorptive filters) suppresses IR. For UV photography it's minimum 1.5mm (usually 2mm is recommended), but that will be cutting red too much for visual, so Leica most likely have used a thinner filter, maybe 0.8 or so. (This guess is based on how thick the M9 sensor filter is measured to be.) This also means that a thin S8612 filter will be extremely transparent to UV. To be honest, I am a little skeptical that Leica wouldn't add some kind of UV cut to their filter stack, but this may be the case nonetheless.

Well, that's not my stance at least. My impression is that the newer Voigtländer lenses have been fantastic. Leica and Voigtländer may have different priorities regarding lens design compromises though. My Nokton 50mm f/1.2 Asph VM is just lovely in almost every way, but LoCA is not a strong point at wide apertures.

LoCA = longitudinal chromatic aberration.

LaCA = lateral chromatic aberration

Here is a good explanation (with graphics and sample images) : https://photographylife.com/what-is-chromatic-aberration

I was about to post the same reference. I found what you posted to be one of the more straight forward and easy to understand the differences and how to handle/avoid or not.

The other confusion I see is people use different terminology/acronyms on the forums and many articles/blogs. This photography-life article does a good job of defining the different terms, but even so, many still deviate with yet even more abbreviations, use of the terms all over the internet. "purple fringing" is an easy out for many of us ha ha

And then if the use/misuse of multiple terms/acronyms were not enough to confuse there are many cases when one lens displays both LoCa/LaCA. Yippie! 

"Unfortunately, many lenses have both longitudinal and lateral chromatic aberrations present at the same time. The only way to reduce these aberrations, is to stop down the lens (to reduce LoCA) and then fix lateral CA in post-processing software like Lightroom and Photoshop."--NASIM MANSUROV

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16 hours ago, LarsHP said:

I searched more on the net, and it appears - in addiction to what you two are saying - that the M9 may not have a (dichroic) UV & IR sharp cutting filter that Kolari Vision says is fused on the sensor. Their competitors / colleagues at MaxMax also has a graph (see link below) showing the transmission of the filter they removed from a M9, and they say that it ought to have a dichroic UV/IR cut filter on it, but there is no such filter. This (according to MaxMax) is the reason why the sensor glass has corroded in M9 cameras. In other words, Leica used glass that will corrode (by oxidation), but didn't cover the surface... Ouch!

Most digital cameras have both a dichroic sharp UV/IR cutting filter and a greenish-blue IR absorbing filter which in combination effectively cuts away both UV and IR and optimizes the light transmission to the sensor. Given there is no dichroic UV/IR cut filter in the M9 (and even newer M cameras), it makes sense to use UV/IR cut filters like those from Hoya and B+W on the lens. That said, these filters will cause color shift outside the center on wide angle lenses, so just using Zeiss T* UV cut filters seems like the best option there.

The above conclusions are actually encouraging to me, since this means that my Kolari Ultra-Thin converted Z6 will have the same properties as a digital Leica M camera.

https://maxmax.com/faq/camera-tech/leica-m9-corrosion

Another case of opinions or misunderstanding or maybe a little bit of both. Some on this forum in particular are keen to suggest UV/IR cut filter for all M cameras. I do understand their rationale and the M8 situation is well known all over the internet. Personally I don't see any evidence of needing to use the UV/IR on any of my images produced with the M10 and I live and shoot the M10 mainly in a subtropical environment. The only other thing I can think of, is all the M lenses I own were made for digital, so maybe the lens used is also a factor to consider. 

The Leica Store Miami duo David & Josh recommend Not to use a UV/IR filter in one of their recent RedDotForum videos claiming it would potentially hurt the IQ of anything other than an M8--they also post the same on their website where they sell the UV/IR cut filter.

If I saw image problems, then I would for sure try the UV/IR cut filter, but to date, I just don't see any need with my M10 kit.

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Let me also add, I am completely open--minded about this topic and always ready to learn and change what I "think" I know if evidence is presented and I can replicate with my own kit. Someone mentioned something about camera "UV leakage" tests. Where can I find such references?

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Leica M8: Jupiter-3Plus, wide-open, UV Light, First image- with UV/IR cut filter, second image- no filter.

With the UV/IR filter- this is what it looks like to the eye. Second image: you do not see this color with the eye.

 

Reminds me of a song.

 

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

 

 

Edited by BrianS
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24 minutes ago, BrianS said:

Leica M8: Jupiter-3Plus, wide-open, UV Light, First image- with UV/IR cut filter, second image- no filter.

With the UV/IR filter- this is what it looks like to the eye. Second image: you do not see this color with the eye

That's interesting.

To be honest i'd not really thought about the fact that different lenses would have different UV performance, i suppose it's obvious in retrospect but that's a good point. Is it the case that the lenses i tend to gravitate towards have a more brutal UV cut? No idea.

Not sure how much PF is down to UV though but it may also explain why different people report different results from camera to camera but i'm not away of anyone really quantifying that.

I'm going to have to find that UV filter around here somewhere and try!

cheers
Paul

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18 hours ago, steve 1959 said:

The real subliminal message on this thread is that voigtlander lenses are rubbish so do not waste your money but buy five times more expensive lenses from leica that have no "loca" at all.

I'm not hearing that message here. If anything, I feel like I read about equal affection for both CV and Leica lenses on this forum and elsewhere. There probably is less sharing of CV lens images here – most of that is on other forums where they are being adapted to non-M bodies.

CV 35 and 50 APO put performance right up there with the Leica 35/50 APO. And maybe Voigtlander will more quickly fill out their APO line over the next year or two.

Edited by hdmesa
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34 minutes ago, paulcurtis said:

That's interesting.

To be honest i'd not really thought about the fact that different lenses would have different UV performance, i suppose it's obvious in retrospect but that's a good point. Is it the case that the lenses i tend to gravitate towards have a more brutal UV cut? No idea.

Not sure how much PF is down to UV though but it may also explain why different people report different results from camera to camera but i'm not away of anyone really quantifying that.

I'm going to have to find that UV filter around here somewhere and try!

cheers
Paul

Old lenses with few and single lens elements that have no (or just one layer of) coating allows a great deal of UV through. Also note that it is the M8, not one of the newer cameras.

If you use modern, multicoated lenses with many lens elements, then the lens itself won't pass as much UV. That which is passed will be very near the visible range. The Summarit 50/1.5 that Jaap has is from around 1950 and the Jupiter-3 is also from just after WWII. (If it's the re-made Lomography version, then it is multicoated though.)

In practical use, it's also about UV relative to visible light. If you use a UV-lamp and expose for it, any lens will let UV through at a certain point. UV in sunlight is a fraction of visible and IR, but at sea and high altitudes tiny particles in the air will reflect UV in amounts that makes it visible and something to consider avoiding (or emphasize for artistic purposes).

Please (everyone here) read this link, if you didn't already see my link in the previous post:

https://petapixel.com/2020/06/04/why-uv-filters-are-basically-useless-on-modern-cameras/

Edited by LarsHP
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29 minutes ago, LarsHP said:

Old lenses with few and single lens elements that have no (or just one layer of) coating allows a great deal of UV through. Also note that it is the M8, not one of the newer cameras.

If you use modern, multicoated lenses with many lens elements, then the lens itself won't pass as much UV. That which is passed will be very near the visible range. The Summarit 50/1.5 that Jaap has is from around 1950 and the Jupiter-3 is also from just after WWII. (If it's the re-made Lomography version, then it is multicoated though.)

In practical use, it's also about UV relative to visible light. If you use a UV-lamp and expose for it, any lens will let UV through at a certain point. UV in sunlight is a fraction of visible and IR, but at sea and high altitudes tiny particles in the air will reflect UV in amounts that makes it visible and something to consider avoiding (or emphasize for artistic purposes).

Please (everyone here) read this link, if you didn't already see my link in the previous post:

https://petapixel.com/2020/06/04/why-uv-filters-are-basically-useless-on-modern-cameras/

The click-bait article title says they're useless, but they come right back and say a good one may be useful. From the article (Zeiss T* UV is 410nm cutoff):

Quote

There is, however, some small combination that could do something. A very aggressive UV filter with a 420nm cutoff point could help on Sony or Canon cameras that generally have slightly weaker UV filters built in than Nikon, Fuji, and Pentax. Depending on your specific model, your Nikon or other model may also have a weaker internal UV filter and could stand to benefit slightly from the extra UV filtration to bring it up to the modern flagship standards.

"Some small combinations that could do something" is sloppy writing – saying, "There are, however, a few situations where UV filtration can be beneficial" would have been more clear.

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I used the modern Jupiter-3+, which is multi-coated.

Nano-Coated optics tend to greatly diminish longer wavelength IR, but more into the band that is past sensitivity of a Silicon based sensor. I gave my Meade 1000/11 to a group that discovered the $4000  nano-coated field-scope killed IR that they were trying to collect. The Meade saved their experiment.

The Canon 50/0.95 is a fine performer on Sensors Unlimited Sensors past 1550nm. I used mine on a $25K imager.

 

You need to know the spectral characteristics of the camera in use to decide on what cut filters to select. For the M8, M9, and M Monochrom: if you use a classic lens and do not want UV light in the image, use a filter. The CCD and cover glass used is by-design sensitive to UV. These are the finest 35mm format  CCD based cameras that money can buy.

Edited by BrianS
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