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B&W sensor only?-- Merged--


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Seen on RFF. The same Kodak sensor has a sensitivity of 0.1 lux at f/1.4 in its color version vs 0.01 in monochrome whilst both versions have the same dynamic range. Would this imply less noise with monochrome?

 

Yes, given that you have set the same ISO. The M9 sensor has a base sensitivity (with Bayer and IR filtering) of 160. If you set the speed to IS0 640 then the signal is amplified 4x meaning noise added by the amplification process, and also less dynamic range. If the new sensor has a base speed of 640, then you do not have that problem, and if you jack it up to 2500, then you are where you was at 640 with the M9. There are of course other sources of noise (shot noise e.g.) but they are comparably minor.

 

The introduction of such a camera would also boost the sales of ND filters.

 

The old man from the Monochrome Age

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A B&W sensor has to compete with B&W film and the only advantage for a digital sensor I can think of

 

You could say much the same about colour sensors and they've done quite well. I'm not interested in this theoretical camera, but for someone who is, the advantages are more than sensitivity.

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Yes, given that you have set the same ISO. The M9 sensor has a base sensitivity (with Bayer and IR filtering) of 160. If you set the speed to IS0 640 then the signal is amplified 4x meaning noise added by the amplification process, and also less dynamic range. If the new sensor has a base speed of 640, then you do not have that problem, and if you jack it up to 2500, then you are where you was at 640 with the M9. There are of course other sources of noise (shot noise e.g.) but they are comparably minor.

Realistically the base sensitivity wouldn’t quadruple; On average, RGB filters absorb about 50 percent of the incident light so without those filters the sensitivity would double. But the good news is that shot noise would be reduced as well, not just noise originating in the sensor itself.

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As a matter of fact I am just reiterating what I’ve been saying on this topic since 2006. The theoretical benefits of a monochrome sensor are well known; after the 10th of May we will either get a chance to see whether it works out as well in practice – or it will remain mere theory.

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Phase One Achromatic Plus Review

 

With all of this as background, a couple of years ago Jim Taskett approached Phase One with a request for a back that shot monochrome (no Bayer Matrix) and which didn't have an IR blocking filter or an AA filter. In other words, just a raw monochrome sensor.

 

One would think that this would be easy enough to accomplish, but it turned out not to be the case. In fact it took some two years and several patent applications on the part of Phase One till the Achromatic back became a reality.

 

Phase One medium format backs are individually "mapped" for their defects – which all sensors have. A monochrome sensor is much less tolerant of these "bad" pixels and rows because the Bayer matrix has a way of "masking" them, thus allowing a higher tolerance for these defective photo sites.

 

Because the Phase One Achromatic has no filtration whatsoever (there is simply a thin glass cover plate over the sensor for physical protection), it records light covering the full visible spectrum, and also from down into the UV to well into the infra-red.

 

Firstly, it makes exposure determination very difficult because the exposure will vary dramatically from what is metered, depending on the amount of IR reflecting matter in the shot.

 

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Not convinced that in a monochrome only world a film camera isn't better. Digital sounds interesting but all this tech talk about more shades of gray. How does that compare with film? Not saying better or worse, work flow matters, but if you are committed to a bw world why not stay in film.

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if you are committed to a bw world why not stay in film.

Probably for the same reason that most people shooting in colour don’t stay with film. What has colour vs. black and white got to do with sensors vs. silver-halide film?

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I fear that color film will be not existing in the not so distant future. Kodak discontinued slide film.Only Fuji left for slide film and even that not anymore in my favorite format 5x7. Color reversal or negative is a much more elaborated production process than B&W film. I can imagine that small production B&W film (like Spur, Rollei film Agfa remnants etc. today) is possible for many years (may be quite more costly than now).

So color has no other long term option than digital but that I think/hope that does not apply to B&W.

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Realistically the base sensitivity wouldn’t quadruple; On average, RGB filters absorb about 50 percent of the incident light so without those filters the sensitivity would double. But the good news is that shot noise would be reduced as well, not just noise originating in the sensor itself.

 

Correct, Michael. A doubling would be more realistic. I simply wanted a theoretical example that was easy to understand and did not demand any mathematics or physics.

 

The old man from the Monochrome Age (Adox KB17)

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Thanks for the link to this very interesting review. I agree that the increased spectral gamut is one main attraction of a camera like this.

 

I used my M8 quite extensively for IR with 092 filters. A RF camera is of course much more convenient for this kind of work than a SLR or a view camera. The focusing problem can be overcome in practice, e.g. by using the f:5.6 d.o.f. mark as a measure of focus adjustment, and by a little focus bracketing; IR is seldom used for action photography. I could not finance my M9 except by selling the M8, but I do often mourn it.

 

The old man from the Monochrome Age

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Actually Michael there is a difference. With a regular sensor I can easily do a lot to fix alter and otherwise change my photo in post processing on the computer. With a black and white sensor only there is very little I can do from the way it has been explained here. In fact all I get is a wonderful high tech super mp digital photo. The latitude of what pp on the computer can do to the picture is somewhat limiting relative to what I can do with a color sensor, such as change the photo from color to b&w and use color curve to simulate filter effects. Given the narrow latitude with a digital bw sensor, why spend all that money for a camera that produces finally in digitial what I can get in tri x?

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After perusing this thread, I was reminded of a discussion on TOP that some might find of interest...

 

Part One

 

Part Two

 

Part Three

 

Note that this was written prior to the speculation about a Leica b/w camera. Mike Johnston, editor of TOP, has always wanted a b/w sensor camera and this delves into the rationale, along with some counterpoints from Ctein, a physicist, photographer and printer who frequently writes for TOP.

 

Jeff

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Thanks Jeff, very interesting articles - I particularly like the analogy of colour to crack cocaine (or sugar!) - that's me down to a T! I need constraints to work against to produce my best work. I tend to loose focus when I have too many choices available to me.

 

 

Christian

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Thanks, Jeff, for an interesting link. I don’t agree with the main argument, that having a B&W camera will force you into visualizing a monochrome world, (well, in a sense of limiting choices it obviously does) whereas a color camera would not do so. I think many photographers are able to see a photograph in black and white regardless of the tool in their hands.

After perusing this thread, I was reminded of a discussion on TOP that some might find of interest...

 

Part One

 

Part Two

 

Part Three

 

Note that this was written prior to the speculation about a Leica b/w camera. Mike Johnston, editor of TOP, has always wanted a b/w sensor camera and this delves into the rationale, along with some counterpoints from Ctein, a physicist, photographer and printer who frequently writes for TOP.

 

Jeff

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May help to have a dedicated B&W camera for some people, be that a Tri-X loaded body or a digicam with B&W settings. Sounds somewhat stupid when shooting raw i guess but not everybody can switch in a snap from seeing tones to colors and vice-versa.

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After perusing this thread, I was reminded of a discussion on TOP that some might find of interest...

 

Part One

 

Part Two

 

Part Three

 

Note that this was written prior to the speculation about a Leica b/w camera. Mike Johnston, editor of TOP, has always wanted a b/w sensor camera and this delves into the rationale, along with some counterpoints from Ctein, a physicist, photographer and printer who frequently writes for TOP.

 

Jeff

 

 

The third piece is really enlightening and interesting.

 

This link (I have posted it before) is very interesting as well:

 

Visual depiction of light loss in Bayer CFA [Page 1]: Open Talk Forum: Digital Photography Review

 

.

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Thanks, Jeff, for an interesting link. I don’t agree with the main argument, that having a B&W camera will force you into visualizing a monochrome world, (well, in a sense of limiting choices it obviously does) whereas a color camera would not do so. I think many photographers are able to see a photograph in black and white regardless of the tool in their hands.

 

For some yes, for others no. Sean Reid, for instance, writes extensively about being able to see only b/w throughout his workflow, including the LCD rendering. This harkens back to film days when, if one had b/w film loaded, all visualization was on monochrome pics. Some even carried a b/w viewing filter to facilitate that process. Thus, for some, it's an important psychological issue to 'get into the zone', so to speak.

 

I was like this in the film world, usually with Tri-X loaded. In the digital world, I consciously prepare for the shot to be either in color or in b/w; rarely do I press the shutter with both in mind. It helps, though, if I stay in a b/w or color mode, as changing requires 'seeing' in a different way. I like the options digital affords, but it's a different mental exercise. Some, especially those who never shot film, lack the discipline IMO and are a bit lazy in terms of visualizing the end result, content to deal with that in the PP stage.

 

 

Jeff

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