View Full Version : Using BTZS with a scanning workflow, how to?

Ralf-Finn Hestoft
27-Apr-2006, 08:50
OK, I got the BZTS software, step wedges and a densitometer and am about to start film testing and have some questions. Since I plan on scanning the negs instead of printing them, are there any adjustments that need to be made in the process?

For example, is there a way to use a step wedge (I have both the 21 step and the 31 step) to determine the ES of the scanner, like you would with different brands of paper?

Do I need to make any adjustments to the G-Bar values since I am scanning as opposed to printing?

Does ViewScan do a better job as scanning BW negs than Silverfast?

Is it a problem that when scanning the 31 step wedge, everything goes to black after about step 26?

Any other tips on nailing a scanning workflow down using BZTS, the densitometer and the step wedges?

As usual, I have all the tools but not enough knowledge...

Thanks in advance,

Ralf-Finn Hestoft

Kirk Gittings
27-Apr-2006, 09:33
I can't help you with most of your questions but Silverfast is better if you want to do much adjustment at the scanning stage, because there are many more tools available. If you heavily manipulate tone, as I do, it is best to make major curve and density adjustments at the scanning stage to avoid the noise build up in the transition areas between tones when you try to make these adujustments in PS. SF is better for this approach than VS.

Brian Ellis
27-Apr-2006, 09:59
I've used both Vuescan and Silverfast Ai (without Suite). I agree with Kirk, I think you can do more with Vuescan. However, I found that it took a whole lot more time to learn how to use Vuescan to its full advantage (and I'm not sure that even now I'm doing that). I didn't think the instruction book that came with Ai was very helpful in that respect. I bought a book from Amazon called "Silverfast: The Official Guide" that was much more useful. However, regardless of what you do with Silverfast, I think it's going to take more time to learn than Vuescan but if you take the time you'll be rewarded.

I've been away from the BTZS system for too many years to answer most of your other questions. However, with respect to the 31 step wedge question, I can't imagine that being able to print "only" 25 distinctive steps is going to be a problem. One of the first clues I got that digital printing was going to be a whole lot better for me than darkroom printing was when I discovered that I could scan and print a 21 step wedge that showed 21 distinctive steps. The only way I had ever been able to do that in a darkroom was with van Dyke brown printing. With "normal" printing in a darkroom you either blow out the bright steps or the dark steps or both depending on your contrast setting. So it's hard for me to believe that the loss of 5 steps out of 31 when scanning is going to be a problem since I doubt you could do that well in a darkroom. But I don't remember ever owning or even hearing about a 31 step wedge in the two workshops I took from Phil Davis or in his book so I can't answer from any real knowledge or experience .

If you don't get satisfactory anwers to your BTZS questions here you might call Dennis at the View Camera Store. I vaguely recall that he is quite knowledgeable about digital printing and I assume that's where you bought your materials.

David Swinnard
27-Apr-2006, 11:37
Be aware the BTZS software only works with 21 steps. They can be the 21 from the typical step wedge or 21 steps you pick from the 31 step step wedge.

I just tripped over this one myself. Phil Davis suggested (via the BTZS forum) to me that picking first six steps from the 31 step tablet, the last six, and then every second one (9 steps) through the middle density ranges would provide good accuracy in the toe and shoulder ranges.

Michael Kadillak
27-Apr-2006, 11:56
It seems to me that there are two distinct objectives in the process. The first is to use the BTZS procedures to expose and develop optimal negatives in a density range consistent with that of silver enlarging paper (DR 1.0 +/-). Although I am not a technological guru I would put money that a "quality" negative that can be attained with the assistance of the BTZS software and the density readings is still the fundamental objective.

With this optimal negative I feel that objective #2 is to use the technology to adjust this basic negative data for optimal output purposes in the digital domain. It is my understanding that the digital process is highly flexible and foregiving and as a result it does not drive the long established BTZS testing procedures and the output that the software produces.

I predict it will be a very steep learning curve.

Good Luck!

Ralf-Finn Hestoft
27-Apr-2006, 12:14

I saw Phil's post to you. Have you tried the plot conversion and if so, how were your results?

To the others, thanks for the info. I guess my main question is what paper ES should I use in my calculations if I am scanning? Just a normal ES of 1.05 (which is what Phil recommends when using the PowerDial when you don't have any info on your paper) or something else? Also, do I need to aim for a lower G-Bar setting as scanners seem to like thinner negs?


Ralf-Finn Hestoft

Ted Chambers
28-Apr-2006, 09:06
I've been interested in this question as well and have not been able to find much information.

I would guess that a scanner is probably similar to grade 0 or 00 paper. On the other hand, as you note, scanners work better (or faster, anyway) with thinner negs.

Rightly or wrongly, I just assume grade 2 paper. (I use the PowerDial - I don't have the Palm software.) Assuming the exposure was right in the first place, that seems to generally give a usable scan. As Michael suggests, the digital process gives a good deal of post-development flexibility.

Kirk Gittings
28-Apr-2006, 09:18
"On the other hand, as you note, scanners work better (or faster, anyway) with thinner negs."

This is flat not true if you mean "thin negatives" in the usual sense. Scanners work better with properly exposed negatives that are developed slightly flat. A "thinner" negative implies thin shadows which are underexposed. Underexposed shadows are a big challenge for scanners as are dense highlights.