Achromatic Plus B&W Digital Back...

[Bernice Loui]

Got a chance to stop by the local Phase One dealer to look at sample digital prints in both color and black & white. They were extremely generous with their time spending well over an hour with me showing me their products and sample images.

This was the first chance I got to look at the current digital medium format backs and the hardware/software related to the digital image production process.

While the color images were good, they failed to impress me. There is something about the contrast range that appears to me as mechanical and less than real. The medium format digital backs do deliver better contrast rendition and resolution than DSLR's and smaller formats, they still appear to me as a artificial and not natural.

The sharpness/resolution is OK, yet I cannot get over the appearance that edge contrast enhanced images produces un-realistic sharpness in the print... Even when these images were produced by RAW files.

They had a B&W specific medium format back, Phase One's Achromatic Plus. While it produces images that are the best digital B&W I have seen, they are still not at the level of really good silver gelatin glossy fiber base paper prints made with large format film larger than 4x5. Again, the sharpness/resolution appears to me as artificial and edge contrast enhanced (these images are produced from RAW files), contrast rendition appears very linear indeed, but not visually appealing and artificial..
http://www.achromaticplus.com/Achrom...hromatic+.html

The B&W prints viewed are digital prints made on both glossy & semi matt photo print papers.

Something remains lacking.. highlighting again the reality that film / digital have an inherently different look and result, good or bad.

Maybe it is me, maybe it is my built in bias from years and years of creating B&W silver gelatin prints from large (larger than 4x5) negatives made using some of the best optics, film, enlarger and etc..

Regardless, this is the current reality and my opinions in the long run may mean not much of anything.. From what I learned today, film in the commercial and majority of other imaging markets is pretty much history.



Bernice

[sanking]

Maybe it is me, maybe it is my built in bias from years and years of creating B&W silver gelatin prints from large (larger than 4x5) negatives made using some of the best optics, film, enlarger and etc..

Regardless, this is the current reality and my opinions in the long run may mean not much of anything.. From what I learned today, film in the commercial and majority of other imaging markets is pretty much history.



Bernice

We all have built in bias. I personally have a bias for hand made contact printing processes.

Whether you begin with film or digital capture, when you take an image into the digital world there are many more possible results than with purely analog methods. Some of these results are so different that they shock, some are much like what you can get with analog methods of printing. I personally find hybrid type printing a more interesting way of making prints because it opens up creative possibilities that are difficult or impossible with purely analog methods.

Sandy

[Nathan Potter]

Sandy reiterates my sentiments about the flexibility of using a hybrid workflow. Bernice I know what you are saying but the differences you mention are difficult to put into words for photographers.

I think the crux of the difference you see relates to differences in the microcontrast within feature edges. Some of this was touched on in other posts here but not really elaborated on. There was a suggestion that comparing digital pixel structure to silver grain structure might be a useful discussion. I think this is so and relevant to your observations.

For fine grained films a typical halide grain size might be 0.5 to 1.0 µm in size. Upon exposure it will grow some depending on the exposure dose; perhaps a factor of two or a bit more. Still a pretty small receptor of photons. Upon film development the growth is more dramatic as larger amounts of silver is formed around the original nucleation site. In shadow area the growth is slight; in highlight areas the growth can be factors of 10 to 100 in size - much more in volume. I suppose, in effect, this can be viewed as a variable dimension pixel. It is in practice a bit more complicated because color films have attached dye couplers to enhance color rendition and the colors may be in three layers, but the principles are the same.

On the other hand the digital pixel has a very fixed spacial dimension with state of the art being, I believe 5 to 7 µm in extent. There is from design and layout necessity a gap between pixels and mostly adjacent pixels alternate between RG and B in a Bayer pattern. The Bayer pattern imposes limitations on the sensor resolution due to lack of full color data for every pixel. This also holds for B&W digital capture but to a lesser degree.
Generally then the minimum pixel size to extract full disclosure of information for each pixel requires toggling adjacent pixels at least one on each side of the pixel addressed. The additional information is so called demosaiced to establish the probable color or B&W density of the pixel being addressed. Such an arrangement forces the equivalent digital pixel to be about 3 times the size of the 5 to 7 µm original.

Essentially the digital capture discretizes the array of pixels in the X and Y plane while the halide emulsion
smears the grains in X and Y thus yields a smoother microcontrast. One can usually detect the difference upon close inspection just as you have noticed. Analog contact printing reproduces the fine detail of the microcontrast to a stunning degree while enlargement may loose some of the microcontrast depending on the hardness of the light source.

I don't think I'm saying anything here that most at this site don't already generally have a sense of. I happen to make use of both phenomena depending on the image subject matter.

Nate Potter, Austin TX.

[jp]

There's a fair chance the printing process for the sample digital prints were enhanced/altered slightly as a normal workflow to tinker with sharpness/contrasts, etc... It could emphasize difference between this camera and it's digital competitors while creating artifacts noticeable to a silver print practitioner.

The camera back described does not do bayer.

[Bernice Loui]

They sent me a RAW sample file from this digital back.

If anyone is interested in tinkering with it or anyone local can make a highest quality print from it (I'll pay for the best print that can be made from it) .. I'll be interested to see it.



Bernice

There's a fair chance the printing process for the sample digital prints were enhanced/altered slightly as a normal workflow to tinker with sharpness/contrasts, etc... It could emphasize difference between this camera and it's digital competitors while creating artifacts noticeable to a silver print practitioner.

The camera back described does not do bayer.

[Bernice Loui]

Thanks Nate for the info.

It appears that part of the solution to this problem with digital is to make a far larger image sensor. This would increase the amount of image information when the image data is created. It all goes back to information theory, Nyquist–Shannon sampling theorem (no less than two samples to retrieve viable information), filtering to re-create the information and....

Once the actual pixel dimensions are up past 20 microns, the optics are no longer the limitation, the limitation becomes the sensor.

While increasing the amount of information and data is technologically possible, is there a market need or does the market have a demand for it?

All this reminds me very much of digital audio when it was initially believed that a sample rate of 44.1 Khz at 16 bits was more than good enough. Turns out, it is not nearly good enough for high definition audio. Problem with the 44.1 Khz sample rate turns out to be a low dispersion/constant group delay filter design and 16 bits is simply not enough once any processing is done.

Only time will tell if the imaging industry tries to move to higher definition.. which is likely market demand driven.



Bernice

[Ken Lee]

Perhaps the photos they showed you were different, but the images shown on their Fine Art Gallery page may not demonstrate the full aesthetic potential of their system. By analogy, to fully appreciate the sound of a Stradivarius or Guarneri we may require the performance of a virtuoso.

[Robert Hall]

It all seems like a lot of money just to post something on Facebook.

[Lenny Eiger]

We all have built in bias. I personally have a bias for hand made contact printing processes.
Whether you begin with film or digital capture, when you take an image into the digital world there are many more possible results than with purely analog methods.
Sandy

I also see this flaw in Bernice's logic. (With all due respect to Bernice and the many others here who would agree with her.) When I discovered platinum, I gave up darkroom printing. For me, there was no contest.

I have since done many other processes. None of them would or should be compared to a darkroom print. I can appreciate the liquid quality of the experience, but I don't like the dried result, an image encased in an emulsion, or as I call it, goop.

The fine art papers that alternative processes use add a lot to the image, IMO. Now that I am also printing with an inkjet, I get to use these fine art papers. The prints match up well to alternative process prints. I am currently printing my own images with Kozo, which is translucent and has some of downright luminescent effects. However, they don't have the image encased in a emulsion, so they don't actually compare. They need to be compared with a platinum print, or something similar.

To come back to the point, when you compare this camera, and a resulting inkjet print, it needs to be compared to the right kind of print, vs a darkroom print.

My guess is that the back is probably pretty good. It looks like it's a matter of getting the right filter on the front for the correct spectral response. Of course, $45K is too much for a camera, IMO, unless you are shooting catalogues. Especially for one that will be obsolete very soon. It seems a very good way of going broke after very few iterations of new cameras every 3 years or so. Then there's being tethered, tilt shift lenses for the 645 - missing (I'm not sure about this)? and everything else...

I want one, but after about 6-10 iterations when the price goes down and they can go untethered, get stuck on my 4x5. Wait, I have a 4x5 already. And it works really well with that Ilford film I use. Why are we talking about this?

;-)

Lenny

[Nathan Potter]

Thanks Nate for the info.

It appears that part of the solution to this problem with digital is to make a far larger image sensor. This would increase the amount of image information when the image data is created. It all goes back to information theory, Nyquist–Shannon sampling theorem (no less than two samples to retrieve viable information), filtering to re-create the information and....

Once the actual pixel dimensions are up past 20 microns, the optics are no longer the limitation, the limitation becomes the sensor.

While increasing the amount of information and data is technologically possible, is there a market need or does the market have a demand for it?

All this reminds me very much of digital audio when it was initially believed that a sample rate of 44.1 Khz at 16 bits was more than good enough. Turns out, it is not nearly good enough for high definition audio. Problem with the 44.1 Khz sample rate turns out to be a low dispersion/constant group delay filter design and 16 bits is simply not enough once any processing is done.

Only time will tell if the imaging industry tries to move to higher definition.. which is likely market demand driven.



Bernice

Large area sensors absolutely need a market to be cost effective to the consumer/photographer. There is an important market already existent, and that is the medical xray imaging industry. There are at least several suppliers of x-ray cassettes for hospital scanning systems. Sizes can be up to 14 X 16 inches or so at down to 50 µm pitch. These would not be too shabby for ULF applications (of course only in B&W). The cost for one cassette now runs about $1000 to $1500. A cassette would be good for perhaps 20000 to 40000 lifetime cycles. Of course one needs a reader with software to dump the data to a computer.

But I think using these for large format is a viable option as I have mentioned here previously. There are limitations using visible light since they are designed for x-ray absorption. I think the most common sensor uses amorphous Si with a scintillator in order to convert high energy x-ray photons to visible light that can then be detected by an amorphous Si type device. However I suspect it would be a simple step to remove the top scintillator material (or not apply it in the first place) and just use the CMOS device for visible light. This would require no special fabrication line beyond what is used currently. The substrate in the case of amorphous Si active devices can be inexpensive glass. The basic design of the current panels require a very thick depletion layer for the capture of higher energy x-rays (100µm for 10,000 eV) but that would be easily compatible with the the penetration depth of visible light of 0.1 to 10 µm. There is refinement of process going on continually with some amorphous pixel pitches down to 30 µm or so. I think we are closer to large area B&W sensors than some realize.

Having come from the IC industry I can see an 8X10, 25 µm pixel pitch sensor (80MP) right on the horizon especially since the medical x-ray industry is being fiercely driven to provide better x-ray resolution, lower noise floor and higher contrast. In fact x-ray phase contrast technology is a recent very hot area.

Nate Potter, Austin TX.