I like to make an enlarged normal contrast negative from a 35mm negative. Is there a reliable reversal process I can do to the orthochromatic film? Any idea?

Thanks

-- Ryuji Suzuki (rsuzuki@rs.cncdsl.com), February 09, 2002

Answers

See my new article Less is More. As you know, the reversal process eliminates the need for an internegative.

-- Ed Buffaloe (edb@unblinkingeye.com), February 09, 2002.

Kodak used to make a direct positive ortho film that worked well for B+W neg. dupes, based on the solarization effect (it's slow !!!). I don't remember by heart the product code, but I can look for it if you are interested. I hope they haven't discontinued the production, as they do with all their nice and useful B+W products...

-- George Papantoniou (papanton@hol.gr), February 11, 2002.

Yeah, there are 2 ways of doing this traditionally...one is to use the kodak film SO-132, Professional B&W Duplicating Film, which will let you dupe a b&w neg in one step, using traditional b&w developers in either tanks or trays. The other is the more preferred method (more control) and that is to make an enlarged interpositive and then to contact dupe the positive onto another sheet fo film for a working neg.

SO-132 will probably be discontinued sometime in the future, it was slotted for this last year, but got an extra year of life after all...the film is orthochromatic and works like a reversal film, i.e. more exposure=lighter density and vice versa. When you contact with it, say from a same sized neg, the speed is equal to that of contact paper--Azo--very slow. When you enlarge onto it, it's a little faster...since you want to make an enlarged neg, you can use this film in either a sheet film holder, or an easel. If you use an easel, I suggest lining it with black construction paper or something dark to keep flare from cutting down on your contrast. I have used _alot_ of this film to dupe older negs by contact, and my main developer has been DK-50 in a deeptank, but you can use almost any developer including D76 or XTOL for this film as well. It's a tricky film to use because it's very touchy with contrast and it can very hard, if not impossible, to duplicate the contrast range of the original negative with this film. It is for this reason, and problems with longevity of the film itself (mostly with the earlier types like so-015) that most archives & such don't use it....I work in such a place and have seen some older versions of this film that haven't fared too well over time...but SO-132 is an improved versions supposedly and has some special processing guidelines that differ from other films. This includes a toning step in either brown toner or selenium, and to eliminate the use of hypo clearing agents and go for a full wash instead.

The two step method involves using either an ortho film (like Ilford's Ortho+ or the discontinued Kodak Commercial Film--you may still find this in some stores) or a panchromatic film (Plus-X or Delta 100 work good). You make an enlarged positive onto this film, process it and then contact that onto a sheet of Ortho+ and process that as the final neg. The control you get with this system is that you can use filters with a panchromatic film to take out stains or blemishes in the original, and you can manipulate contrast or dodge & burn as well. The interpos should be darker than a normal print...it's not made to look good visually, but made to contain all the tones so nothing is lost going over to the neg again. The interpos become the "master" and you can make as many dupes off it as you need...I use Plus-X and Ortho+ for this...or Ortho+ for both steps. It might be easier to do them both on Ortho+ because you can use a safelight & probably just do it like paper...SO-136 is the most direct method, but may not work too hot with certain types of negs...it's also sorta expensive, running at $45 for a 25 sheet box of 4x5...the 8x10 is about $90 or so a box. By comparison, Ortho+ is about $12-15 a box of 25 4x5s...there used to be a direct duplicating roll film as well, but I've never used this, so I can't comment too much more about that...could be someone else has? Hope this helps, a great ref book is Kodak's "Copying and Duplicating in B&W and Color"...it explains all this in detail and will give you densitometer aim points as well. They recommend using Tech Pan and TMX 100 now for the 2-step method. Most of the films used in the past for this are long gone....blame that on digital.

Good luck.Opinions expressed in this message may not represent the policy of my agency.

-- DK Thompson (kthompson@moh.dcr.state.nc.us), February 14, 2002.