Red filter for monochrom?

[Erikvw]

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Does anybody know why Leica does not produce red filters for the monochrome or B/W film cameras?

I know there are yellow, green and orange filters, but no red filter.

[Stef63]

To my knowledge Leica produced several red filters for ltm lenses (in the era of their ltm film cameras). I have a ltm Thambar with a clip on POOGL (dark red) filter.  But if you use google you will find also E-type red filters from Leica/Leitz.

On the other hand B+W have red filters for b&w photography in most sizes.  And B+W filters are by all means as good as Leica filters. 

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[mmradman]

Red filter was discussed here in the past, the consensus is orange is better option if one need sky (blue) darkening filter, with red focus starts to get shifted.

[BrianS]

On the CCD based M Monochrom: With a red filter- the light meter picks up more light than the sensor, add 1/3rd~2/3rd exposure compensation. Focus shift with a red filter is dependent on the lens, the APO-Lanthar shows no focus shift. Same will be true of the APO-Summicron. Use the IR index of the lens as an indicator of focus shift. On the original Summicrons it was close to the F2 mark- you will not see focus shift.

[mmradman]

17 hours ago, BrianS said:

On the CCD based M Monochrom: With a red filter- the light meter picks up more light than the sensor, add 1/3rd~2/3rd exposure compensation. Focus shift with a red filter is dependent on the lens, the APO-Lanthar shows no focus shift. Same will be true of the APO-Summicron. Use the IR index of the lens as an indicator of focus shift. On the original Summicrons it was close to the F2 mark- you will not see focus shift.

Not sure how much IR index would be available to typical M camera & lens user.

I don't recall ever seeing IR index on focus scale of the contemporary M lenses, also can't see it on later R lenses.  I know IR Index exists as SMC Pentax-M and Nikkor AiS lenses in my hands have it, all theoe lenses belong to 1970s/1980s design and production. 

[BrianS]

I tend to use classic Leica glass- the IR index on my 5cm F1.5 Summarit is just outside of F2. Once the marks started falling within F2, I figure they quit putting them on.

 

 

[mmradman]

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On 4/20/2021 at 12:14 AM, BrianS said:

I tend to use classic Leica glass- the IR index on my 5cm F1.5 Summarit is just outside of F2. Once the marks started falling within F2, I figure they quit putting them on.

 

 

Using vintage lens with IR marking is fine but not really applicable to majority of photographers who don't have access to such lens.  With red filter issues first advise would be not to use it, but if one insists perhaps stopping-down or use of EVF would be more applicable here. 

[BrianS]

With digital cameras- a simple test clarifies the issue. With Leica lenses - there will not be much shift, the color correction is very good. I have lenses where the IR index is at the F8 DOF indicator. Others- no shift at all in IR. About the same issue as the shift caused by spherical aberration. 

[IkarusJohn]

On 4/19/2021 at 1:36 AM, BrianS said:

On the CCD based M Monochrom: With a red filter- the light meter picks up more light than the sensor, add 1/3rd~2/3rd exposure compensation. Focus shift with a red filter is dependent on the lens, the APO-Lanthar shows no focus shift. Same will be true of the APO-Summicron. Use the IR index of the lens as an indicator of focus shift. On the original Summicrons it was close to the F2 mark- you will not see focus shift.

Nor with the 0.95 Noctilux

This whole storm in a teacup started with digilloyd saying the original Monochrom was flawed because you got focus shift with red filters.  Intrigued, I tried a dark red filter (either Heliopan or B+W, I can't recall - probably a mix of both) on lenses I had which fitted the filters.  I could detect NO colour shift (not surprisingly, as the camera is a Monochrom) and NO focus shift.

I was using modern APO lenses, from memory.  Not really surprising that apochromatic lenses address this issue.  But then, I guess this was just my experience in practice, rather than an important theoretical issue identified by a person who hates rangefinders and the Monochrom in particular.  Perhaps he actually found the issue in his "testing", I don't know.  After my own testing, I decided it was clickbait.

I do use yellow (on my 50 Summilux ash), orange and red filters, and haven't had an issue.

Edited April 21, 2021 by IkarusJohn

[Sjz]

8 hours ago, IkarusJohn said:

Nor with the 0.95 Noctilux

This whole storm in a teacup started with digilloyd saying the original Monochrom was flawed because you got focus shift with red filters.  Intrigued, I tried a dark red filter (either Heliopan or B+W, I can't recall - probably a mix of both) on lenses I had which fitted the filters.  I could detect NO colour shift (not surprisingly, as the camera is a Monochrom) and NO focus shift.

I was using modern APO lenses, from memory.  Not really surprising that apochromatic lenses address this issue.  But then, I guess this was just my experience in practice, rather than an important theoretical issue identified by a person who hates rangefinders and the Monochrom in particular.  Perhaps he actually found the issue in his "testing", I don't know.  After my own testing, I decided it was clickbait.

I do use yellow (on my 50 Summilux ash), orange and red filters, and haven't had an issue.

I use yellow, orange and red on my M10M and not had an issue either.  (APO 50, APO 75, ‘lux 28).  
 

I was worried about using red after reading about focus shift, just proves not to be an issue for me.  
 

The occasional mis-focussed shot happens with or without any of them, my error not the kit’s.

[mmradman]

This is the link that was posted here not long ago, i think it is good read with respect to M246 and use mono filters.  There may slight spectral response differences with other MM models but probably still a good guide.

https://themachineplanet.wordpress.com/2015/09/16/the-leica-monochrom-typ-246-and-filters/

[tgray]

On 4/21/2021 at 6:07 PM, BrianS said:

With digital cameras- a simple test clarifies the issue. With Leica lenses - there will not be much shift, the color correction is very good. I have lenses where the IR index is at the F8 DOF indicator. Others- no shift at all in IR. About the same issue as the shift caused by spherical aberration. 

28 Summicron (both of them) shifts pretty bad with red filters on the M10M.  I want to say it shifted with a B+W 041 filter as well.  

FWIW, I haven't found much difference in contrast with red and orange filters, but I've not tested particularly thoroughly.

[LeicaS2]

I finally did a test of yellow, orange, and red for sky contrast.

I regularly leave a yellow on my lenses with the M10M just for making portraits more "normal".

I use silver eft (now 3) for making clouds look great.

My test was with a red crane against a cloudy sky. The red filter makes the red crane look lighter, but the darkening of the sky is not that much different than an orange filter.

Then I ran the combo through Silver Eft 3 with high contrast and structure, and also LR with contrast and Dehaze. The orange and red filters show a clear difference versus yellow when contrast is applied. 

Conclusion: use  LR or Silver Efx for cloud contrast for much more effect than a red filter. Use a red filter if you want something that is red in the picture to look lighter. An orange filter is probably the adequate  choice for clouds unless you are Ansel.

 

So the first comparison is basic out of the box, the second is Silver Efx 3, the third is trying to duplicate Silver Efx 3 using LR sliders. The third shows the most difference between Orange and Red filters to my eye.

Your thoughts?

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[jaapv]

Be aware of possible focus shift when using a red filter.

[IkarusJohn]

5 hours ago, jaapv said:

Be aware of possible focus shift when using a red filter.

This was Digilloyd’s great controversy over the Monochrom - you use filters, but the sensor is so thin (compared to film emulsion) that focus is off with a red filter, which rendered the camera fatally flawed. Hmm, not so much in practise. 

Yes, theoretically a strong red filter can exacerbate a shift of the red spectrum at the depth of focus (on the sensor plain) with poor apochromatically corrected lenses. But in practise, I’ve yet to find it. I suspect the theory is stronger than the reality. Much like the subtle differences between modern APO lenses, or focus shift in lenses which transitioned Leica’s move to digital, this is a small problem. 

I should add that the only camera likely to suffer from this hypothetical problem is the M9 Monochrom (Henri). The M240 and M10 based cameras have live view, if you think this is likely to be a problem. 

 

[jaapv]

The problem was Digiloyd's ignorance of the cause. It happens on film as well and has been known for as long as rangefinders exist. It has nothing to do with the filter stack. If you have a lens with lateral CA the focus will shift to the red fringe. 

It  becomes more serious as the red deepens. With IR filters it can be severe.

Edited June 6, 2021 by jaapv
added text

[tgray]

On 6/5/2021 at 7:42 PM, IkarusJohn said:

Yes, theoretically a strong red filter can exacerbate a shift of the red spectrum at the depth of focus (on the sensor plain) with poor apochromatically corrected lenses. But in practise, I’ve yet to find it. I suspect the theory is stronger than the reality. Much like the subtle differences between modern APO lenses, or focus shift in lenses which transitioned Leica’s move to digital, this is a small problem. 
 

It's very lens specific (obviously) in my experience.  The 28 Summicron does it as does the Zeiss C-Sonnar.  I think no one would be surprised at the latter, but I was with the former.

Edited June 10, 2021 by tgray

[IkarusJohn]

3 hours ago, tgray said:

It's very lens specific (obviously) in my experience.  The 28 Summicron does it as does the Zeiss C-Sonnar.  I think no one would be surprised at the latter, but I was with the former.

Depends which version of the Summicron you have.  The first version was highly praised, particularly on film M cameras and the M8.  It didn’t really work that well for me (probably my copy, so I sold it), and it performed poorly on the SL.  I suspect it was one of those lenses found wanting with higher resolution sensors, with their very unforgiving depth of focus.  Leica then released the second versions of the ASPH 35 and 28 Summicrons, which seem to have fixed the problem.

As you say, the shift in the depth of focus will be lens specific (not sure it is “focus shift” in the way people use that expression - unlike the 35 Summilux ASPH, pre-FLE, it’s not a case of focus shifting with changes in aperture). I think it’s largely a theoretical problem, limited to lenses poorly apochromatically corrected on the original Monochrom.  

If you have a later version of the Monochrom it won’t be a problem using red filters if you use live view . 

[hdmesa]

On 6/10/2021 at 8:22 AM, tgray said:

It's very lens specific (obviously) in my experience.  The 28 Summicron does it as does the Zeiss C-Sonnar.  I think no one would be surprised at the latter, but I was with the former.

With my 50 Summilux BC and an orange filter, I have to use live view when shooting wide open. However, using a light red filter on my CV 50 APO shows no change, and rangefinder focusing is fine wide open at f/2. Sounds like all non-APO lenses can be affected to varying degrees, at least at wide apertures.

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[bilbrown]

On 6/5/2021 at 4:49 PM, jaapv said:

The problem was Digiloyd's ignorance of the cause. It happens on film as well and has been known for as long as rangefinders exist. It has nothing to do with the filter stack. If you have a lens with lateral CA the focus will shift to the red fringe. 

It  becomes more serious as the red deepens. With IR filters it can be severe.

 

 

Orange acts the same as RED with the M10M and M246. I found this an issue the other night with my M10M, the focus shift was so bad I literally thought my eyes (new glasses) were off. The next day I shot the same scene without a filter at the same time and it was perfectly in focus.

I may want to mention, that live view didn't actually help much. This of course could be "user error".. but it makes me want to check a few more times and test. 

This was this the normal Leica orange filter, btw.