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Why IR cut filter on CV 15?


AGeoJO

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This lens is actually great and very inexpensive, in Leica terms, at least. I can't help by noticing that people try to put IR filter on this lens using various methods. While I understand the need to improvise the 6-bit coding on this lens to take advantage of the Leica microlens system to minimize vigentting, I don't quite understand the need for the IR cut filter for this particular lens. I have this lens and use it practically almost 100% for landscape and even if I use it for something else, the amount of purple color shift, if any, relative to the entire picture is very small. I tried a Zeiss ZM 15mm in November last year on my at that time new M8; the body had the original firmware, there was a faulty hardware in the body, the lens didn't have any 6-bit coding and, of course, IR cut filter wasn't available, but the results for landscape shots were gorgeous.

 

Don't shoot me and it is definitely not my intention to upset people with this post but could someone enlighten me, please? Am I missing something? Am I way off base?

 

Thanks,

Joshua

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This lens is actually great and very inexpensive, in Leica terms, at least. I can't help by noticing that people try to put IR filter on this lens using various methods. While I understand the need to improvise the 6-bit coding on this lens to take advantage of the Leica microlens system to minimize vigentting, I don't quite understand the need for the IR cut filter for this particular lens. I have this lens and use it practically almost 100% for landscape and even if I use it for something else, the amount of purple color shift, if any, relative to the entire picture is very small. I tried a Zeiss ZM 15mm in November last year on my at that time new M8; the body had the original firmware, there was a faulty hardware in the body, the lens didn't have any 6-bit coding and, of course, IR cut filter wasn't available, but the results for landscape shots were gorgeous.

 

Don't shoot me and it is definitely not my intention to upset people with this post but could someone enlighten me, please? Am I missing something? Am I way off base?

 

Thanks,

Joshua

 

 

I don't shoot landscapes at all (with this lens or any other lens :D ). I use it for architecture and interiors. You can say that in those situations I might need the filter for that?

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Hi Sean,

Thank you for your reply. Yes, I understand that but the color shifts affect only black artificial fabrics, right? On the M8, the CV 15 has an effective focal length of 21mm, which is considered ultra wide. And as such, if used for landscape, do we still have to use an IR cut filter then?

 

Joshua :)

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I'm very happy to use my unfiltered CV15 on landscapes, and outside generally. Unless it's, say, a street shot in which people are wearing black synthetic clothing it works fine. I take care of vignetting in Photoshop, but even that's rare because any vignetting that is there tends to be "hidden" by the subject matter. Home or commercial interiors are a different matter as there are lots of opportunities to experience the dreaded magenta shift. Anyway, I still prefer my Hasselblad 903 superwide and that old-fashioned stuff called film for interior work!

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but generally speaking the color shift noted with the M8 occurs in other than just synthetic blacks

I find foliage and other floral colors affected

unlike the magenta shift for synthetic blacks, this is far more difficult to correct in post

with the ir/cut filter, the colors appear far more vibrant & life like

Jono Slack has posted here & on dpreview that he finds this less a problem, but I find that shooting foliage without the filter gives them a tired off yellow cast that I find upleasant

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I don't shoot landscapes at all (with this lens or any other lens :D ). I use it for architecture and interiors. You can say that in those situations I might need the filter for that?

 

Steven,

Did you see color shifts on your current interior shots without any filter?

 

Phil,

That's my point exactly. You are right street shots may or will pickup the color shifts but how big are they objects wearing black synthetic fabrics using an ultra wide angle lens? My favorite lens for street shots is the 28mm Summicron ASPH and I do have an IR cut filter on it.

 

Arthur,

I used Jamie's alternative profile before firmware 1.102 was available and before I had any IR cut filter to get a semi-decent "black" of any black synthetic fabrics. The greens definitely were effected and became dull. The current firmware enables us to choose "lens coding on", "lens coding plus UV/IR on" and both off. The greens and floral rendition I am getting are fine to my eyes. The convenience is to leave the setting "UV/IR" on all the time without having to remember changing the setting back and forth.

 

Thank you for your input, guys. The reason, I guess, I am asking this question is because there are a lot of threads on this forum that deal with efforts of trying to mount IR cut filter on this lens.

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Hi Sean,

Thank you for your reply. Yes, I understand that but the color shifts affect only black artificial fabrics, right? On the M8, the CV 15 has an effective focal length of 21mm, which is considered ultra wide. And as such, if used for landscape, do we still have to use an IR cut filter then?

 

Joshua :)

 

Hi Joshua,

 

Actually, the color shifts can come from all kinds of subject materials (not only textiles) of various colors. Black textiles are just one obvious type but the effect is much broader. Some people can live with those color shifts (when they occur) or even prefer them but they do exist.

 

Cheers,

 

Sean

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In landscapes, the biggest effect of IR contamination on color is that foliage runs too yellow (or even, with some evergreens, almost brown or orange). Wood with strong colors (cherry, paloverde) may shift as well, but the 'hot' greens are the big issue.

 

Shifting the foliage color from yellow towards blue is fairly easy, via the various tools for shifting hues - UNLESS there are also "true" yellows such as flowers in the picture, which then also shift towards green.

 

I shot for 6 months with my 15 and 21 lenses and no IR correction - waiting for filters and/or coding and/or firmware. I got some great shots. Now that I CAN block the IR, my shots are even better.

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Thomas - As the images appear on my monitor, viewing in Safari, and accepting there are different colour management, and colour space issues at play: I find the filtered image greens unconvincing and would choose to work the colour of the unfiltered file instead.

 

...............Chris

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but generally speaking the color shift noted with the M8 occurs in other than just synthetic blacks

I find foliage and other floral colors affected

unlike the magenta shift for synthetic blacks, this is far more difficult to correct in post

with the ir/cut filter, the colors appear far more vibrant & life like

 

My feelings exactly.

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Thomas - As the images appear on my monitor, viewing in Safari, and accepting there are different colour management, and colour space issues at play: I find the filtered image greens unconvincing and would choose to work the colour of the unfiltered file instead.

 

...............Chris

 

cHRIS; i DONT THINK I have preset the WB correctly.

This was more to show that there is IR light when you shoot landscape/nature.

if its more compealing I dont know. However if I shoot I would like a consistent result and therefore I try to use allways IRCUT filters.

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Again, thanks for your input, guys.

 

I have IR cut filters on all my other Leica lenses; the latest acquired filter is a 60mm for my Nocti. Again, I am not questioning the merit of IR cut filter but I was just simply baffled by the feverish level of threads dealing with ways to mount a filter on the CV15. Since the lens is actually a bargain but of excellent quality, the ownership of this lens is really high. I guess if you could just simply screw-in a filter on this lens, it would have been a non-issue.

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In landscapes, the biggest effect of IR contamination on color is that foliage runs too yellow (or even, with some evergreens, almost brown or orange). Wood with strong colors (cherry, paloverde) may shift as well, but the 'hot' greens are the big issue.

 

Shifting the foliage color from yellow towards blue is fairly easy, via the various tools for shifting hues - UNLESS there are also "true" yellows such as flowers in the picture, which then also shift towards green.

 

I shot for 6 months with my 15 and 21 lenses and no IR correction - waiting for filters and/or coding and/or firmware. I got some great shots. Now that I CAN block the IR, my shots are even better.

 

With critical evaluation, Andy Piper's experience is my experience exactly. The color shifts from foliage and wood shift in varying directions. I also find seasonal foliage and wood shifts. Correction becomes very labor intensive.

 

Joshua - if you find that no filter is to your liking, then don't use a filter. Try running a test with and without a filter, however, to compare the difference and convince yourself.

 

Helene

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Again, thanks for your input, guys.

 

I have IR cut filters on all my other Leica lenses; the latest acquired filter is a 60mm for my Nocti. Again, I am not questioning the merit of IR cut filter but I was just simply baffled by the feverish level of threads dealing with ways to mount a filter on the CV15. Since the lens is actually a bargain but of excellent quality, the ownership of this lens is really high. I guess if you could just simply screw-in a filter on this lens, it would have been a non-issue.

 

Even then there would have been the issue of shading with the lens plus filter.

 

Cheers,

 

Sean

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