Colour vs B&W: why is there any difference?

[Dez]

I often hear of some lens being "good for B&W" but not necessarily so for colour. I have even seen people posting that a particular lens is sharper in B&W than in colour. It is not obvious to me that this makes sense.

All currently available monochrome films are panchromatic: they are sensitive to the entire visual spectrum. I have seen many colour pictures showing colour fringing, or other aberrations indicating that the optical performance of the lens varies over the spectrum; the results tend to be multicoloured blurs or variations in sharpness depending on the colour of a particular picture element. It seems to me that the same lens with a B&W film of the same sensitivity would have to produce the very same blurs, only in various shades of grey. Aberration-limited resolution and contrast would be the same.

There are of course differences between various films in B&W and colour, but we are talking about lens performance not film performance, so these differences don't count. And I suppose if one could dig up some narrow-spectrum orthochromatic film somewhere, the performance of the lens may be a lot better, but there really isn't such an option anymore.

So the only thing I can see that would appear to show a difference in the colour vs B&W performance of a lens would be that colourful blurs are perceived as more annoying than grey blurs, although resolution and contrast are the same, and so a lens could get away with a higher level of blurring due to colour aberrations with B&W film than with colour.

Comments please?

Cheers,
Dez

 

[mfogiel]

I think, that the misunderstanding relates to equating film with B&W and digital with colour. In digital, there are problems related to a different refractive index of sensor filters, than that of the air: lenses made for film, were assuming a constant refractive index of the medium (air) between the lens and the sensor (film), while digital has introduced a whole range of problems on the way - all this makes the performance of "film" era lenses, particularly traditional wa designs more problematic. Talking about film only. the chromatic aberrations were always present, but given the typical degree of enlargements of film, were only visible with longer fl lenses - in fact, normally only the teles were ever produced as APO lenses. A notable exception has been the 50 Summilux ASPH.

 

[Photo_Smith]

Also with digital the sensor is in one plane, that is not true with film which has a depth.
Different wavelengths of light are focussed either in front or behind the ideal point of focus which shows up more in the corners.
Some sensor makers put microlenses to he;p with this effect.
Also old uncoated lenses are better with mono film because of added flare and chromatic aberrations being chromatic just don't show up as well.

 

[Dwig]

In the older literature the description of a lens being or not being "good for color work" had to deal with the lens' contrast. Low contrast lenses, typical of uncoated lenses, would often do well with B&W, where contrast can be adjusted in processing, but not with color.

The same still applies today with film. With digital you can correct for a low contrast lens just as easily in a color image and in a B&W image.

 

[Dez]

Some photographers, refer to lenses which produce a magenta cast on the edges of very wide angle photographs, taken with full frame cameras as useless for color, but OK for black and white.

Let's put digital imaging aside for the moment; that's a whole other can of worms. PM's comment supports the idea that the factor is a perceptual difference in the acceptability of coloured vs grey blur, and yes this sort of aberration seems to be more common with wides. But I have heard the same comments referring to 50mm and longer lenses as well. Even in old literature, one can find a lens which is specifically recommended for colour work. I suspect that as suggested above, high vs low contrast may be the dominant difference between acceptable and non-acceptable lenses for colour work.

Cheers,
Dez

 

[Roger Hicks]

Dear Dez,

The argument that any modern lens is "better for colour" or "better for B+W" is surely nonsense. Gone are the days of non-achromats; gone are the days when contrast control was even slightly difficult. Different lenses suit different photographers and different subjects.

Incidentally, as far as I am aware, Ilfird Ortho Plus is still available. Just don't trust the Google images of ortho photographs, which include (without my permission) one of my pictures on Ilford HP5 Plus, clearly labelled as such...

Cheers,

R.

 

[Sejanus.Aelianus]

I think Dwig got it.

I've seen claims that "radioactive" lenses, such as the Pentax Takumars of the Spotmatic era, could generate hard to shift colour casts as they got older, but I haven't experienced that with any of my Takumars from that period.

 

[Roger Hicks]

Not sure I agree with those my post refers to. I am not among those "some photographers" that worry so much when using digital bodies -- even with older lenses.

I find the image usually trumps aberrations.

No dissent on either assertion, and I apologize for misrepresenting you inadvertently.

Cheers,

R.

 

[KoNickon]

It was always my understanding that it related to contrast, as Dwig says. A multicoated lens passes through a higher percentage of light to the film, and so is supposed to provide higher contrast and thus render colors more accurately. Single- or uncoated lenses work better for black and white than for color, simply because you're dealing with shades of grey (which can be adjusted in processing and printing, as Dwig says).

Cosina came out with one or two lenses that were available as multicoated or single-coated, and I understood the single-coated versions were marketed as best for a "classic" look (i.e. for black and white photography).

 

[Murchu]

My impression of it, is higher contrast and aberration-free lenses were preferable for colour. Aberrations tend to be objectionable in colour to me, but not in b&w. Contrast is personal preference in my opinion, but imagine more like higher contrast in their colour images than lower contrast. I imagine the same lens will have the same aberrations and contrast whether you are shooting b&w or colour, but whether those are objectionable, depends on the individual users.

Not sure about the sharpness aspect you mention, but then sharpness is a perceptual thing, and not the same as resolution.

 

[redisburning]

I mean I hear the contrast argument and my personal preference/experience plays out differently.

The best lens I have on color is the 50mm Makro-Planar
The best lens I have on b&w is the 50mm Makro-Planar

I prefer the color rendering of some lenses over others (Im particularly fond of Leica R 60mm macro elmarit and unfond of 55/2.8 micro nikkor) but to me this is preference, not better or worse.

 

[alienmeatsack]

Add all of the above to the pot, then toss in the fact that you can have 10 identical lenses from the same company that all have a little different rendering of the image and it's details and then you wonder.

Is it personal preference? Is it your eye's capabilities vs another persons, seeing the detail or color shifts etc? Is it that one lens vs another from the same company with a little different personality? Is it the air pressure, temperature, location, etc?

Is there truly a way to 100% prove any of this in one way or another minus a total locked down controlled lab?

I think it would be interesting to see if you could prove it was one of the above or something else. I know everything is subjective based on many factors. So which is the factor that is the dominant one for this particular conversation? User? Glass? Environment? Chemicals? CCD? Processor? Who knows.

I do wonder all of this myself. I've never really had 4 of the same exact lens on hand to try test shots and see if the lenses vary, or to replicate shots in a way that has any meaningful variation that is replicable. But my eye only sees what it sees, and I see very differently then the person next to me. And so on.

 

[JoeV]

In theory, a monochrome image of narrow bandwidth, using either colored filters, narrow spectrum film or both, will be less bothered by chromatic lens artifacts, since such artifacts are wavelength dependant. In practice, and as Roger so eloquently states it, it matters little with modern lens designs.

~Joe

 

[BlackXList]

A slightly different take on it since with compacts the lens is permanently attached.

I've noticed that my Contax T3 seems to ever so slightly overexpose, (maybe it's the "Sonnar Glow" haha) with colour negs this is great, but with b/w (admittedly C41 b/w) it gave images that lost something to that look.

The Yashica T4's Tessar gives me a much more pleasing look on B/W.

Both are outstanding lenses, but personally I prefer the way the T4 renders b/w.

This is probably easily explainable by those more versed in what Sonnar Vs Tessar actually means than me haha

 

[Dez]

A slightly different take on it since with compacts the lens is permanently attached.

I've noticed that my Contax T3 seems to ever so slightly overexpose, (maybe it's the "Sonnar Glow" haha) with colour negs this is great, but with b/w (admittedly C41 b/w) it gave images that lost something to that look.

The Yashica T4's Tessar gives me a much more pleasing look on B/W.

Both are outstanding lenses, but personally I prefer the way the T4 renders b/w.

This is probably easily explainable by those more versed in what Sonnar Vs Tessar actually means than me haha

Maybe, but I suspect it may have more to do with variations in the light meters of the two cameras. It is an interesting example of a difference in what is optimum in the exposure, more than the lens, however. Conventional wisdom was always to slightly overexpose negative film, as it was hard to unblock deep shadows, and underexpose transparency film, since once a highlight is burned out, you're out of luck.


Cheers,
Dez

 

[Dez]

Cosina came out with one or two lenses that were available as multicoated or single-coated, and I understood the single-coated versions were marketed as best for a "classic" look (i.e. for black and white photography).

I have wondered about that business of single-coated lenses being somehow better for black and white, and so far I don't buy it. It would appear that the "advantage" they provide is to reduce the dynamic range of an image by filling the dark shadows with veiling glare. This is not adding image information, in fact it is reducing it. If the lens compressed the dynamic range somehow, reducing highlight burnout and shadow blockage as you can do with high-end digital cameras that would be a different story, but a piece of glass can't do that.

These days most people pass pictures through Photoshop or the like, and can reduce contrast or soften the image if desired. It seems to me that the best bet is to always start with an image that contains the maximum amount of information. I can make a Summicron picture look like it was taken with a Summar. I don't think I can make a Summar picture look like it was taken with a Summicron.

Cheers,
Dez