I think the three things which combine to result in the lack of color purity you observe with DSLR sensors are:
1-bayer filter interpolation of color from a b&w sensor.
2-the straight line tonal response of a digital vs analog.
3-AA filters to counteract bayer filter interpolation artifacts.
The best color I have seen from digital has always come from the larger sensors in digital backs OR from similar technology and design decisions employed in smaller sensors. Usually, these sensors have some of these qualities in common:
1-the elimination of or use of extremely weak and or better/more expensive aa filters.
2-higher dynamic range.
3-better low iso image characteristics in exchange for high iso/low noise.
I do think the higher dynamic range property is very important in the ability to use a more extreme curve in trying to get the most out of color purity and tone as they are related.
A foveon style bw-sensor would be the way to go if you want good bw, and I think that something similar to foveon technology will be the future for color photography too. Getting rid of many of the problems that the bayer array introduces.
ulrikft wrote:
A foveon style bw-sensor would be the way to go if you want good bw, and I think that something similar to foveon technology will be the future for color photography too. Getting rid of many of the problems that the bayer array introduces.
A Foveon-style sensor would be very poor for B&W since all you really need to do for a dedicated B&W sensor is to remove the bayer filter pattern from a standard sensor. Kodak did this with the (rare) DCS760m, which produced superb B&W output.
ulrikft wrote:
A foveon style bw-sensor would be the way to go if you want good bw, and I think that something similar to foveon technology will be the future for color photography too. Getting rid of many of the problems that the bayer array introduces.
Actually, if you really want good B&W, get a a CCD sensor without a RGB filter (a Foveon style filter is irrelevant for B&W, just like the Bayer filter, you don't need 3 different color sensitives at each photosite or alternating photosite to capture B&W). Monochrome versions of most bayer filters are made by sensor manufacturers.
Kodak produced a monochrome version of one of it's early DSLR's and it is, from what I've seen, spectacular and very sharp. Noticeably more resolution that the equivalent bayer-filtered version. Of course, you would have to go back to using color filters to control the tonalities of the image (because you are not capturing colors that you can select later). Of course, the best thing about digital, color digital that is, is that for B&W you don't need to bring a half dozen red, orange yellow, green and blue filters with you, as well as assess filtration and constantly change them out to optimize a particular image before you capture it.
mawz wrote:
A Foveon-style sensor would be very poor for B&W since all you really need to do for a dedicated B&W sensor is to remove the bayer filter pattern from a standard sensor. Kodak did this with the (rare) DCS760m, which produced superb B&W output.
Lotusm50 wrote:
Of course, the best thing about digital, color digital that is, is that for B&W you don't need to bring a half dozen red, orange yellow, green and blue filters with you, as well as assess filtration and constantly change them out to optimize a particular image before you capture it.
My experience with digital lead me to the conclusion that I would get better results if I applied the correct filtration prior to capture. The resulting color were more "pure" than instances when I used ACR to adjust temperature.
From what I've read, ACR profiles were created for daylight and tungsten samples while other color temps are extrapolations from these color points.
In short, if I'm photographing in shade. I've gotten better results on the final file by using a warming filter and setting the camera on daylight in comparison to files corrected for color temp in post.
I'm not a B&W photographer, but based on this experience I think you would get a better final image if you used the correct B&W filter for your intention of the scene at capture and then applied the B&W conversion from this very distorted color file. I'll have to test this some time.
Tariq Gibran wrote:
I think that is a very good point!
Theoretically yes. In practice, you will need at least something like DPP monochrome with Orange filter to produce skin tones similar to B&W film without any filtration.
edwardkaraa wrote:
Theoretically yes. In practice, you will need at least something like DPP monochrome with Orange filter to produce skin tones similar to B&W film without any filtration.
Or the very nice B&W conversion tool in PS CS3/CS4 which give you virtually limitless control over filtration -- and shade of orange -- or any other color, or combination of colors -- you like.
Lotusm50 wrote:
Or the very nice B&W conversion tool in PS CS3/CS4 which give you virtually limitless control over filtration -- and shade of orange -- or any other color, or combination of colors -- you like.
Yes. I have used PS channel mixer extensively for B&W conversions, which I believe is similar to the tool you mention. I think that a straight conversion to B&W uses somethink like 25% R, 50% G and 25% B, while the normal response of a standard B&W film should be more like 70% R, 25% G and only around 5% B.
edwardkaraa wrote:
Yes. I have used PS channel mixer extensively for B&W conversions, which I believe is similar to the tool you mention. I think that a straight conversion to B&W uses somethink like 25% R, 50% G and 25% B, while the normal response of a standard B&W film should be more like 70% R, 25% G and only around 5% B.
The "Black and White" tool in CS3 and CS4 is a significant advance over using the "Channel Mixer" tool offering more functionality and control. You should try it.
The best B&W digital conversion tool I have used, even to this day, is the older Imaging Factory B&W Pro Photoshop Plugin which is unfortunately no longer being updated. Here is what it looks like:
edwardkaraa wrote:
RGB channels in digital are somewhat overlapping, while scanned film tends to show more separate, or not as homogenous RGB channels. Scanned film gives deeper reds, blues and greens.
The reason I believe is that digital tries to keep all RGB channels within the limit of the color space, similar to a relative colorimetric rendition. (
The color filter array bandpass *is* wide in digital CFA's.
In my experience, though, the colors I get with my calibrated cam are *far* more accurate than any print/slide I've seen.
How much of your experience is due to years/decades of seeing film prints, and *expecting* to see those color interpretations? This would be similar to *perceiving* grain as sharpness...
skid00skid00 wrote:
In my experience, though, the colors I get with my calibrated cam are *far* more accurate than any print/slide I've seen.
How much of your experience is due to years/decades of seeing film prints, and *expecting* to see those color interpretations? This would be similar to *perceiving* grain as sharpness...
Agreed!
I went to digital around 2002 when I looked at the 2MP digital images a friend took at my sons birthday party. The color was incrediibly pure, clear, clean, despite the very low res. They were far better than the scanned color files I was getting from my Mamiya 6x7 slides and negatives!
Afterr going digital, I could not believe how dirty and nosiy and impure my film scans were. Digital next to film looks makes it like you took a negative or slide and left it in the street for 5-6 weeks. Just ugly, ugly noise and artifacts (from the film scan.) I gave up 6x7 for my Canon D30 3MP images. Just couldn't go back to the crud I saw from film. That is why digital rezes up so much better.
Film is "dirty" - the grain and/or dyes are really noise. The substrate is really poor. We are fooled into thinking there is more detail beacuse of the random artefacts that hide real low-level detail. But blow it up and it looks like what it is - garbage.
Or, in another approach - take a digiital file and add noise, you can make the image look just like film!
The only film I still use if 4x5, because I can't justify a MFDB right now.
Also, FWIW: Lightroom allows great mixing of color for B&W images. Looks pretty similar to the tool displayed above.
I think it's depending whether you look at prints or at a computer screen. In print, noise/dirt etc is seldom visible and can actually make your pictures look sharper. This is very apparent when discussing digital noise, difference is night and day between print and screen - just take a few step back and watch a "noisy" picture at a normal viewing distance and you'll be surprised.
Too many people are judging pictures by 100 % crops on the screen. Poor them.
edwardkaraa wrote:
Many don't realize that the noise they see in scans is not film grain but actually grain aliasing.
You probably should define "grain aliasing" for the uninitiated. If you've got samples it would be helpful to show them to illustrate.
Further what you see isn't necessarily grain aliasing, as your comment suggests, it merely can be. It is far from a certainty and it really is not that common.
See the discussion here: http://www.normankoren.com/Tutorials/MTF8.html
Norm Korens summary comment on this is as follows: "Film images are composed of grain, and film (especially negative film) can have more grain than most people realize, especially if they haven't seen sharp prints. Film grain is often mistaken for scanner noise or grain aliasing (a real effect, but somewhat rare)."
I see actual grain (not merely aliasing) in my scans -- certainly with the 5400 dpi scans, but also, depending on the film with the 4000 dpi scans. Scan high enough to resolve the grain and you limit the potential for grain aliasing.
I went to digital around 2002 when I looked at the 2MP digital images a friend took at my sons birthday party. The color was incrediibly pure, clear, clean, despite the very low res. They were far better than the scanned color files I was getting from my Mamiya 6x7 slides and negatives!
Afterr going digital, I could not believe how dirty and nosiy and impure my film scans were. Digital next to film looks makes it like you took a negative or slide and left it in the street for 5-6 weeks. Just ugly, ugly noise and artifacts (from the film scan.) I gave up 6x7 for my Canon D30 3MP images. Just couldn't go back to the crud I saw from film. That is why digital rezes up so much better.
Film is "dirty" - the grain and/or dyes are really noise. The substrate is really poor. We are fooled into thinking there is more detail beacuse of the random artefacts that hide real low-level detail. But blow it up and it looks like what it is - garbage.
Or, in another approach - take a digiital file and add noise, you can make the image look just like film!
The only film I still use if 4x5, because I can't justify a MFDB right now.
Also, FWIW: Lightroom allows great mixing of color for B&W images. Looks pretty similar to the tool displayed above. ...Show more →
If you were getting better images from your D30 than from you 6x7 Mamiya slides...then you must have been murdering your slides. I have shot Pentax 6x7 for many years and when I went to digital ( 5D ), the resulting images were no where close to what I can get from the 6x7 slides. I judge the results using 16x24 and 20x30 prints and there were huge differences in both resolution and true colours. Yes the digital images looked good at 100% on the screen, but when they needed to be uprezed to make the photos, they quickly turned to mush.
Only reason I moved to digital was convenience...not image quality.
