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View Full Version : How do I dupe an 8x10 negative?



John Kasaian
20-Nov-2008, 18:43
I want to try fiddeling with a negative but I'd hate to muckup the original so duping seems like the way to go but....uh...how do I go about it? What film should I use, etc...?

Don7x17
20-Nov-2008, 19:13
I presume you are talking about a B&W negative....

In the days when Kodak made B&W duplicating film, this would be an easy chemical process. (single sheet of film, that kept ithe image as negative)

You don't mention what you want to do to the negative -- increase/decrease contrast? locally bleach/intensify? scratch up the negative? paint it? or ?? Do you want to get an approximate copy of the negative (zone to zone, etc) or are you willing to accept something that resembles your original negative in the midzones but is changed in shadows and highlights? (see below)

I guess you could try going to a film positive (TMX or your choice of film...) and then a second time to a film negative. You'd have to do a lot of experimentation to get it somewhat right. Then you'd want to consider some masking steps to keep the contrast somewhat similar (remember those characteristic curves of the film? the toe and shoulder...well you'll be applying these twice in this process - to both ends of your negative but inverted each time. they don't cancel. Could be an interesting negative at the end....

Or maybe someone has a stash of 8x10 frozen duplicating film?

but you'd be better off, in my opinion, getting a decent drum scan and use photoshop as needed to produce a digital negative for contact printing (avoid enlarging). there are a number of means to output a digital negative. this might be best - and you can use photoshop to mess around with the negative....and you can make more if some damage occurs in your process....

Filmnut
20-Nov-2008, 19:42
I pretty much agree with all of the above, a scan and output would likely be the best.
I used to do this professionally, for a few customers before the d.....al revolution, and the B&W duplicating film was the best of a tough situation, as it never really worked as well as I would of liked, although I could not custom tailor the developing as much as I would of preferred, being in a production lab environment. Just like doing a copy neg, there are some losses, even when contacting.
Ektachrome Dupe film can also be used, but this could get costly, if you can get the film, and it would take a number of tries to get even close.
If you do get some B&W duplicating film, my recollection is that it is EXTREMELY slow. Maybe in the region of 5 ISO?? Not sure of the actual speed, but quite a few stops slower than the Ektachrome.
Keith

Merg Ross
20-Nov-2008, 20:57
How bad is the original negative? Is it a moonrise photograph with a graveyard, shot in New Mexico? If so, take a chance and muck around with the original. You could mass produce prints, and retire early.

Donald Miller
20-Nov-2008, 21:29
http://unblinkingeye.com/Articles/EnlargeNeg/enlargeneg.html

While this deals with enlarged negatives using traditional means, I see no reason that it would not work with duping.

I have used this technique and it does work.

John Kasaian
20-Nov-2008, 22:48
I presume you are talking about a B&W negative....

In the days when Kodak made B&W duplicating film, this would be an easy chemical process. (single sheet of film, that kept ithe image as negative)

You don't mention what you want to do to the negative -- increase/decrease contrast? locally bleach/intensify? scratch up the negative? paint it? or ?? Do you want to get an approximate copy of the negative (zone to zone, etc) or are you willing to accept something that resembles your original negative in the midzones but is changed in shadows and highlights? (see below)

I guess you could try going to a film positive (TMX or your choice of film...) and then a second time to a film negative. You'd have to do a lot of experimentation to get it somewhat right. Then you'd want to consider some masking steps to keep the contrast somewhat similar (remember those characteristic curves of the film? the toe and shoulder...well you'll be applying these twice in this process - to both ends of your negative but inverted each time. they don't cancel. Could be an interesting negative at the end....

Or maybe someone has a stash of 8x10 frozen duplicating film?

but you'd be better off, in my opinion, getting a decent drum scan and use photoshop as needed to produce a digital negative for contact printing (avoid enlarging). there are a number of means to output a digital negative. this might be best - and you can use photoshop to mess around with the negative....and you can make more if some damage occurs in your process....

Don,
I can see that digital would be a very useful way to do what I want done, but I like futzing around in my darkroom with stinky chemicals too much!
What I need to do is get rid of some dust spots. I could simply spot the prnts but I'd prefer to get the problem solved once and for all if possible. It's part of my lazy nature I guess!

John Kasaian
20-Nov-2008, 22:50
I pretty much agree with all of the above, a scan and output would likely be the best.
I used to do this professionally, for a few customers before the d.....al revolution, and the B&W duplicating film was the best of a tough situation, as it never really worked as well as I would of liked, although I could not custom tailor the developing as much as I would of preferred, being in a production lab environment. Just like doing a copy neg, there are some losses, even when contacting.
Ektachrome Dupe film can also be used, but this could get costly, if you can get the film, and it would take a number of tries to get even close.
If you do get some B&W duplicating film, my recollection is that it is EXTREMELY slow. Maybe in the region of 5 ISO?? Not sure of the actual speed, but quite a few stops slower than the Ektachrome.
Keith

Come to think of it I have seem some aerial duplicating film from time to time of ebay, I wonder if that would work??

John Kasaian
20-Nov-2008, 22:55
How bad is the original negative? Is it a moonrise photograph with a graveyard, shot in New Mexico? If so, take a chance and muck around with the original. You could mass produce prints, and retire early.

Hi Merg,

I may end up doing just that. The dust spots are in the clouds so they aren't all that noticable (unless I make enlargements---then they might look more like UFOs---they do seem to be flying in formation!) Still, making dupes would be another skill to learn and just might keep me from accidentally toasting my negative.

John Kasaian
20-Nov-2008, 22:57
http://unblinkingeye.com/Articles/EnlargeNeg/enlargeneg.html

While this deals with enlarged negatives using traditional means, I see no reason that it would not work with duping.

I have used this technique and it does work.

Thanks for the link Donald!
I happen to have a stash of 8x10 APHS in the freezer next to the Eskimo Pie. :)

Peter K
21-Nov-2008, 11:31
I want to try fiddeling with a negative but I'd hate to muckup the original so duping seems like the way to go but....uh...how do I go about it? What film should I use, etc...?
There are duplicating films for radiographic purpose aviable like FUJI MI DUP also in 8 x 10". Such a positiv-working film avoids the loss of defination with an interpositive. Normaly such a film is processed with a processing machine but it works with paper developer too.

Peter K

ic-racer
21-Nov-2008, 12:57
I suspect you will have even more dust spots to deal with after duplicating the original with traditional methods.

I would just practice on some no-good negatives and then just go for it on the good one.

If you are abrading the back of the negative to reduce dust spots (like a re-touching machine would do) I would be interested in our results as some day I would like to learn those techniques.

Brian Ellis
22-Nov-2008, 08:26
I found it difficult to make good dupes in a darkroom, partly because the specialized materials that used to be made for this purpose aren't made any more. Plus it was no fun and a lot of work (at least for me). There are at least three problems. First, you'll have to go from your negative to a positive and then back to a negative because dupe film isn't made any more. I tried xray film as Peter mentions and it wasn't any good at all for a photograhic negative though mine wasn't the Fuji brand he mentions, it was a film Freestyle sold as direct negative-to-negative film. I don't know if Freestyle still sells this stuff or not but if you see them advertising negative-to-negative film it's xray film.

In any event, at both steps you not only lose detail, you also gain contrast. So your first battle is coming up with a developer to minimize the contrast increase. I used two different developers, highly diluted D76 (1-6 I think) and highly diluted Dektol, I don't
recall the dilution. You could experiment and see what works.

Using highly diluted developer creates your second problem - the strength of the developer decreases dramatically with each negative/positive you put through it so it becomes difficult to make accurate adjustments to your exposure times and development times. Which also adds to the drudgery because the developer exhausts itself quickly and you need to frequently mix up new batches, get the temperature right, etc. And of course using a fresh batch changes your times once again.

The third problem is the dust problem you mention. I used a black Marks-a-lot pen for the spots. You can't be very precise with a normal Marks-a-lot pen but if my memory is right it didn't matter, the excess ink surrounding the spots didn't show up in the final print.

Good luck, making dupes in a darkroom these days is a very time-consuming, frustrating process but if you have even slight masochistic tendencies you might like it.

bwchrome
22-Nov-2008, 20:12
...sorry to plug myself, but help is help. :)

regards
dw

http://www.filmrecording.net/ABOUT.html


I want to try fiddeling with a negative but I'd hate to muckup the original so duping seems like the way to go but....uh...how do I go about it? What film should I use, etc...?

EdWorkman
23-Nov-2008, 09:45
Photo warehouse sells "continuous tone duplicating film" in various sizes. It's almost certainly for Xray duping, but I have no specifics.
When Kodak was still available i used this as well, as it was and is MUCH cheaper.
It is slower than the Kodak, but useable. Tough for projection duping with anything other than really well exposed/developed negs. I did many dupes using paper developer and contrast increase is a hazard. Now , when I use it, I use a film developer concentrate and find that contrast increasae is easier to avoid.