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View Full Version : New FREE paper on SLIMT contrast reduction for B&W and COLOR, film, paper, everything



davidkachel
17-Apr-2019, 11:57
In the early 1990's I published a 4-part series of articles on contrast reduction (contraction) in "Darkroom & Creative Camera Techniques" magazine. (I published a lot of articles, but this series is the best known.)

Part III of that series, on "Selective Latent Image Manipulation Techniques" was a big hit, but over the years has been mostly forgotten, in large part due to the massive shift to digital photography.

Recently I have begun to suspect that all the hype about the return of film may not be entirely composed of hype and perhaps this information needed to be put out there again, for all the newcomers.

So, here it is: a complete rewrite and update of the original announcement, free for the taking. And this time, you can even get the chemicals from a photographic supplier instead of weighing out your own. (Freestyle sells the kit and NO, I don't get a penny from it.)

Manipulating the latent image after exposure and before development is my own invention, worked on for a decade and a great source of pride to me before the digital cross-town bus ran it and me down. So, I am hoping it will be of use to a whole new generation of photographers.

Enjoy,

dk

(I thought I had posted this and it seems to have vanished. Admin, please remove this if it is a duplicate post.)

davidkachel
17-Apr-2019, 12:43
I can't find the other post, so I guess this is it.

Ulophot
17-Apr-2019, 12:47
David, thank you for this update. I look forward enthusiastically to reading it. I'm the one who wrote an article published in Tim Layton's Darkroom Underground magazine last year, showing the result of pushing the contrast-wise process to N-3 in a high-contrast portrait, using HP5 and D-23. My tests showed it a significant improvement over two-bath D-23 in maintaining low value density. It is a valuable tool in my repertoire. I haven't properly tested SLIMT for prints yet, but I'll bet it will also come in handy on some difficult subject.
Best wishes!

Paul Ron
17-Apr-2019, 12:54
interesting article. im curious to find your other articles.

thanks for the information david.

davidkachel
17-Apr-2019, 13:15
interesting article. im curious to find your other articles.

thanks for the information david.

A number of them are here: www.davidkachel.com/monographs.html

But they have not been updated in a very long time and typos and other errors have crept into them over the years. I will be redoing the series on filters and the Primacy of Local Contrast but donít know when. The local contrast article appears as an appendix in my just released book on photogravure, but as originally written. The other two contrast reduction techniques are outdated, but the first article in the contraction series is still valid, though it could stand updating, too.
dk

Pere Casals
17-Apr-2019, 13:16
Many thanks, I'll try this technique for night photography. I'm confident that it will be useful to me.

swmcl
17-Apr-2019, 15:11
Many thanks David for your work and willingness to share.

I have my own summary of David's work that I tried. It might help you Pere.

David's techniques do work.

Rgds,
Steve

Randy Moe
17-Apr-2019, 15:44
Very good read, it reads fast. I like that.

I have plenty of Ektascan and will be trying your techniques.

Has it been tried with Gas Burst?

I normally use compressed air gas burst Ektascan in 1/100 Rodinal, still water stop and TF5. I second burst every 10 seconds. I shot Rodinal and still water stop.

davidkachel
17-Apr-2019, 16:17
Very good read, it reads fast. I like that.
I have plenty of Ektascan and will be trying your techniques.
Has it been tried with Gas Burst?
I normally use compressed air gas burst Ektascan in 1/100 Rodinal, still water stop and TF5. I second burst every 10 seconds. I shot Rodinal and still water stop.

I have never used it with gas burst, though I did some investigations of gas burst agitation for Georgia Pacific years ago. I see no reason it shouldn't work.
I use open tube rotary processing in trays (also one of my articles) and prefer that. Let me know how it works with the gas, please.
dk

Randy Moe
17-Apr-2019, 16:28
Yes, I also see no reason it would not work with gas burst.

I will test SLIMT in trays first, as I won't need as much working solution.

Or I will cut Ektascan to 2X3 and process sheets in the Nikor waffle holder insert for Nikor cans.



I have never used it with gas burst, though I did some investigations of gas burst agitation for Georgia Pacific years ago. I see no reason it shouldn't work.
I use open tube rotary processing in trays (also one of my articles) and prefer that. Let me know how it works with the gas, please.
dk

EH21
17-Apr-2019, 22:23
Thank you for posting this information. I am interested to experiment with this technique. I think I have already purchased the bleach kit from the PF.
Are there any sample images from this process posted?

davidkachel
23-Apr-2019, 18:48
Hi,
Though the kit has Photographer's Formulary on the label, they are not selling it. They are only packaging it for Freestyle. So, you can't have bought it from PF.
There are no sample images. Sorry. This group of techniques has already existed for more than a quarter century and is therefore well proven.

PRJ
23-Apr-2019, 19:23
I've used David's technique for bleaching back silver prints before developing. Over the years people have stated that it wasn't necessary, but I don't argue with them since they probably never tried it. I don't need to SLIMT often, but it saves the bacon at times making something difficult much easier. I'm looking forward to reading the update. Thanks.

davidkachel
24-Apr-2019, 20:49
Over the years people have stated that it wasn't necessary...

I suppose it isn't "necessary", but neither are shoes. However, BOTH are damned convenient!! ;-)

Fagrid
26-Apr-2019, 17:47
Hi David. My apologies if you covered this in the text and I just didn't comprehend it, but I had a thought. In the second to last section, you covered extended development of film treated with SLIMT, and said that the film can go back to its untreated density. Are there any variations on this that can lead to increased effective film speed without the associated contrast enhancement of traditional extended development? Basically, do your SLIMTs have the proportionally inverse effect of extended development, where treating the film and then extending its development will effectively cancel one another out in terms of film speed? Or do they act at different rates, so that extended development of a SLIMT treated negative will result in increased film speed with lessened (or, I suppose, heightened) contrast?

I am generally very bad at explaining things, so I hope that this makes some amount of sense.

On another note, I greatly appreciate your effort in writing this document, and releasing it for free. I look forward to trying it.

koraks
27-Apr-2019, 05:53
I gave it a try last night for fun, using some very old Brovira paper and a negative that was a bit too contrasty. To my surprise, I found that I need to dilute the 10% concentrate by an amount of 1+100,000 (yes, 100k) to shave about 1.5 grades off the paper's native contrast. I did stepwise dilutions starting from the suggested 1+1000 in Kachel's paper, but this proved to be way too strong, and the effect seemed to follow a more or less linear decrease with exponentially higher dilutions. I went up to 1+200,000 which still yielded a significant decrease in contrast compared to the untreated paper.

davidkachel
30-Apr-2019, 11:19
Hi David. My apologies if you covered this in the text and I just didn't comprehend it, but I had a thought. In the second to last section, you covered extended development of film treated with SLIMT, and said that the film can go back to its untreated density. Are there any variations on this that can lead to increased effective film speed without the associated contrast enhancement of traditional extended development? Basically, do your SLIMTs have the proportionally inverse effect of extended development, where treating the film and then extending its development will effectively cancel one another out in terms of film speed? Or do they act at different rates, so that extended development of a SLIMT treated negative will result in increased film speed with lessened (or, I suppose, heightened) contrast?

I am generally very bad at explaining things, so I hope that this makes some amount of sense.

On another note, I greatly appreciate your effort in writing this document, and releasing it for free. I look forward to trying it.

Fagrid,
My apologies for the late response. I just canít seem to force the software here to send me notices of new posts.
Extended development after bleaching does not / should not, restore the original (potential) characteristic curve. Remember that latent image bleaching works more efficiently on areas of heaviest exposure. It all depends on the film and developer of course and should vary substantially with variations in both. But extended development should result in the establishment of a moderate midtone bump and a slight shoulder. The end result of an experiment using a standard SLIMT with normal development on one negative and a stronger SLIMT with extended development on another, should result in two negatives with roughly identical density ranges but different shaped characteristic curves, the latter having stronger midtones and softer highlights than the former.
However, my experimentation with this particular application of the SLIMT techniques thus far has consisted of simple ballpark guesses when I have wanted to use it, and no quantitative measurement. My guesses have been quite accurate and I am basically lazy. It is an area wide open for fresh eyes. ;-)

As for film speed, yes, extended development should provide a slight boost depending on the degree of additional development and the developer used. Maybe half a stop at best.

Doremus Scudder
10-May-2019, 11:59
David,

Thanks very much for this. I've been using the techniques you outlined originally, specifically for contrast reduction of B&W films, with great success for years now. I'm looking forward to reading the update.

Best,

Doremus

davidkachel
10-May-2019, 12:06
Doremus, thanks.
Please pass the word whenever you can. So many newcomers have no idea.