Zone System and Drum Scans - Same as paper?

If I'm using the zone system to expose my negs (tmax 100) and my

intent is to scan then on an Imacon, Tango, or some other high end

scanner, should I expose/develop any differently than i would for a

grade 2 paper and condenser enlarger. Most of these scanners can

reportedly handle a Dmax of 4.1 which is about 13.6 stops.

Perhaps the high-end scanners are radically different, but it is generally better to produce a softer negative - one that will be well within the range of the scanner.

 

In Photoshop or other editing tools, one can always add contrast, ad infinitum. However, if the negative exceeds the range of the scanner, no amount of fiddling will bring detail to black shadows or white highlights.

 

<p>I use Tmax 100, but shoot it at around 50. It gives <a href="http://www.kenleegallery.com/peony6-03.htm" target = "xxx">nice results</a>, even when scanned on a "prosumer" scanner.

I don't think you can translate the D-max of a scanner to the number of stops of light can be exposed on film. Fuji for example publishes the Dmax of their negative film at 2.5 which in scanning terms gives you the difference in density betweeen the base plus fog and a piece of fogged film. Everything else falls in between. If you now compare this piece of film to a piece of transparency film given the same treatment you will see a vast difference in the density of the film.

Where the problem comes in the sanner's ability to epand that compressed density range into a useful image. This is the reason that many people complain that their negative film scans are flat and lacking in contrast compared to slide film.

Do you need to expose in the same way. i would say no because in order to print to grade two paper you need to compress the tonality of the film so that it can fit on the paper. Where you are going to scan, you ensure that the detail you want is captured both in the shadow portions and the highlight portions of the film and you don't need to worry about compressing the range to fit the paper because you get the scanning software and the image editing software to do it for you.

I am scanning with an Epson 3200, which is not in the same class as an Imacon, but the principles are still the same. I do almost exclusively negatives, both color and b/w. I am still experimenting, so I don't know the complete answer to your question, but I do have some information I can share with you.

 

I use Vuescan, and if you use the Ctrl key, you can read raw densities as opposed to RGB values. I don't know if these are the same as you would get with a true densitometer, but they do seem consistent with what I would expect. With normal development of a b/w negative, I usually get densities less than 2.0. Typical Zone VII-VIII densities are what you would would expect in a normally dveloped negative using the Zone System. Even the lowly Epson is capable of delivering a dmax of 3.4, which is way above anything you could plausibly need in a negative.

 

The simplest way to think of this is as follows. Use the Zone System and develop normally, whatever the contrast range. After you scan, use the curves control to lower or raise the overal contrast, accomplishing much the same effect as you would were you to use variable contrast paper. This is one variation of the standard Zone System.

 

On the other hand, in principle you might gain some advantage if you overdeveloped to produce negatives with higher maxium densities, as long as these still fit in the dynamic range of the scanner. The more of that range that you use, the more information you have in the scan in terms of number of possible shades of gray. But if you overdevelop you are going to magnify grain and perhaps produce other undesirable effects. There is no way to determine the best balance of all these factors except to experiment.

 

The good news is that unless the negative is grossly underexposed, chances are you can use the curves tool to produce a reasonable final image.

I would agree in general with Ken. I find that if the upper zones have no detail, then the scanner cannot produce detail that isn't there in the first place. However, you can fudge some by scanning a high contrast neg as a low contrast scan to capture as much highlight detail as possible, then adjust final contrast in PS. I have been using consumer grade scanners: Epson 2450 and Minolta Dual Scan III with Vuescan and the Minolta software.

TMAX100 has a very long straight line to its H+D curve. That

means you can over expose the highlights without compressing

them to the point where you lose local contrast. Since I started

doing all my darkroom work digitally I have deliberately aimed to

get more light into the shadows by overexposing, and allowed

the highlights to fall where they will.

 

This gives more density to the shadows, which makes it easier

for scanners to reproduce their tonal subtleties without

excessive noise. The extra density in hightlights is well within

even consumer scanners' abilities, so unlike conventional

printing, the extra overall density range of the negative presents

no problem. I do however find it fairly essential to scan into a 12

or 16 bit file, reducing to 8 bits with a custom curve appropriate to

each particular image in Photoshop.

 

With a more traditional film like TriX where the shoulder starts to

bite early on you risk losing your highlight contrast by doing this.

With the Tmax films it's not an issue.

I've been playing with this for over a year. I think I have an answer that makes sense, at least for me. The answer is, expose and develop your negatives as if for grade 2 paper and condenser enlarger. You gain nothing by increasing the density of the negative, and you loose plenty:

 

First, while it may be true that the scanner can read through dense negatives, there are problems associated with dense negatives. Increasing density means increasing film grain, and also means decreasing sharpness (certainly with solvent developers, and usually with acutance developers as well. The problem is in the increased time in the soup to get the increased density). At least, that's what I have found in experiments on my drum scanner with negatives up to Dmax of 3.6.

 

Second, it is much easier to get a good scan of a less dense negative, at least with my scanner and software. The more dense the negative, the harder I have to work the scanning parameters to get a good scan. It depends on your software whether or not you can even do this. I've tried the same dense negative on my drum scanner and on an Epson 2450 using ViewScan, and I can't get an exceptable scan from ViewScan - it just doesn't have the controls (you have to change the shape of the scanners response curves to compress the highlight (dense) areas, at least with Tri-X, and VueScan doesn't [yet] give you that level of control). Using a grade-2-paper-dense negative, I can get an exceptable scan from both scanners, no problem.

 

Third, the more dense the negative, the worse it experiences the Callier effect. This is especially true of drum scanners, and less so of CCD scanners. The net effect is that the denser areas of the film show reduced contrast due to light scatter in the negative during scanning.

 

Fourth, dense negatives and their inherent increased graininess lend themselves to grain aliasing. Again, more of a problem with drum scanners and less with CCD scanners. But at least with most drum scanners you can minimize this problem, but again you have to work at it. With CCD scanners, well, there it is.

 

BTW, you can't equate Dmax with a number of stops out of hand. That relationship is not just a one stop = .3d linear relationship. It depends on the negative's gamma, or contrast index, which defines the density range of a one stop exposure change, not the scanner. And photographic film is not linear - it has toes and shoulders. In other words, a one stop exposure range gets compressed into a smaller density range in the toe than it does in the straight line portion of the characteristic curve.

Scan the image normal if the neg is perfect.

 

To double check look at the histogram (this is where the zone system translates into

digital) I teach all my students the zone system before they touch digital because its

all over it. and they can work by the numbers.