How do I dupe an 8x10 negative?

[John Kasaian]

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]

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]

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]

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]

http://unblinkingeye.com/Articles/En...nlargeneg.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]

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]

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]

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]

http://unblinkingeye.com/Articles/En...nlargeneg.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]

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