Negative enlargement???

So, I want to enlarge a 4*5 negative to 8*10 negative. I know I can

put the 4*5 neg. in my enlarger and project it down onto a 8*10

negative. I think the proceedure is to go from original neg. to

interpos to another neg. neg. by contact printing. Here is my

question. Why can't I reverse the original negative, in the negative

holder, and that way when I project it down it will be reversed and I

won't need an interpos. Will this work? Thanks, David

The problem is that when you make a negative of a negative, you get a positive. Printing paper is actually a negative material. It is negating a negative. Make sense? So, if you want a negative as the end result, you have two choices. Either make the interpositive, so it can be reversed again onto the 8x10, or you have develop the 8x10 as a "positive" even though that seems backward. Does that make sense? There is a reversal to consider.

Think of it this way -

 

Film can ONLY respond to light. Dark areas like shadows have no light. So they come out WHITE on the film where the light areas (lots of light) react with the film to make a DARK area. This is reversed on the printing paper.

 

So it goes like this for a picture of say a black cat in a dark room -

 

Dark (origonal subject) ---> Light (film) ----> Dark (print paper).

 

Now what you want to do is this :

 

Dark ----> Light ---> Light.

 

Which really doesn't work to well. You need to go Dark ---> Light ---> Dark ---> Light.

 

Simple really.

David might just be playing with us with this question. But here's a true story that happened to me about ten years ago.

 

I shot some exteriors of a new model home for a local builder. I used 4x5 and shot transparencies because he was going to reproduce these photos in a sales brochure.

 

I delivered the film to the builder and he held the transparency up to the light to view the image. He then flipped the transparency over and looked at it from the emulsion side.

 

He paused a few seconds and then he asked....."Why can't I see the rear of the house ? "

Greetings,

 

You basically have three choices: 1) Enlarge the negative digitally and have it output on to film by a pro lab, or printer. 2) Enlarge the negative by making an interpositive, as you mentioned. 3) Enlarge the neg by "reversal" processing; check Ed's site: http://unblinkingeye.com/Articles/NbyR/nbyr.html for more info.

 

You can't simply reverse the negative in the carrier as you mention as you will end up with a positive image, not a negative.

 

Regards, Pete

OK Thanks folks. I get it dark object - light object - dark. I see where flipping it just wont work. No way around the interpositive. So. Next question: should I contact print the original 4*5, and then project the 4*5 interpositive on to the 8*10 neg. , or project the original 4*5 onto the 8*10 and contact the final negative 8*10 negative? I know which would be cheaper, but which would be the best as far as keeping as much of the original image. Thanks

I did an apprenticship for a guy who enlarged 6X7 negs to 8X10" negative material using the Arnillian (sp?) reversal process. The negative was developed half way, then exposed to a 100 watt light bulb and then developed to completion. He then had a 6X7 full toned negative, that he enlarged onto 8X10 negative material.

 

I'm sure there are simpler ways of achieving the same results, but this guy just loved trying out new (old) processes.

david -

 

try negative duplicating film from photo warehouse.

it is single step negative to negative.

 

i have contact printed with it a bunch and know folks that enlarge

onto it.

 

a slow film, might be a long enlargement time, but worth

trying since it is so cheep.

 

- john

There are a couple ways around the interpositive. One is to use duplicting film for the enlarged negative. That way you'll be making an enlarged duplicate of the negative and so you eliminate the intermediate step of making a positive. However, whether you use an interpositive or dupe film, this whole business of making enlarged negatives isn't simple. Controlling contrast is a big problem, partly because each time you make a new negative you lose some of the detail and also increase the contrast, partly because lith film is often the film of choice and it's inherently contrasty. I did quite of lot of this a few years back and it was a real pain, I hated it. Another way is through a bleaching process developed by Liam Lawless and described in detail in the first several ssues of "A World Journal of Past Factory Photography" or something like that. It's a publication devoted to alternative processes. I have the first six issues of it and I can give you the e mail address of the publisher if you really want to pursue this method. I never tried it but from reading about it, it looked like a better method than anything I did try. You also could develop film using the T Max reversal process, which would produce a positive original, then enlarge it onto film which would give you a negative. Digital negatives avoid many of the problems associated with making enlarged negatives in the darkroom but they too aren't that easy to do, especially at home with an ink jet printer.

Kodak have <a href="http://www.kodak.com/cgi-bin/webCatalog.pl?section=&cc=US&lc=en&product=KODAK+Rapid+Process+Copy+Film+(RPC)">this stuff.</a> Which is a direct reversal film used with standard (ie non-reversal) processing.<p>I'm sure that Agfa do something very similar as well.

As mentioned above, and as used by many alt process guys, it usually winds up being a 2 step process. If you look around somewhere in a thread here, there is quite a bit of talk about doing it and getting good enought results "for" alt processing since they need a dense neg. Your other option might be shooting Scala and using that for an enlarged neg, but then, you'll need to outsource the processing, althought someone somewhere I think kind of figured it out. Again the Tmax reversal kit is you home processing solution for a pos. Btw, check Freestyle; I thought they had a neg copy film in larger sizes.

The problem is that alot of the films for negative duping have been discontinued in the past few years. Like Pro Copy, Commercial Film, SO-132 Professional Duplicating (this was a one-step dupe film for b&w), even the Agfa film is gone. Agfa had another film, N330P, that I think Chicago Albumen Works uses, and is the sole distributor for the US. Ilford Ortho Plus is one of the few films left that would work easily for 2 step neg duping. I asked CAW about a replacement method for SO-132 a couple of years ago...they told me how to use Delta 100 or Plus-X as the interpos and Ortho Plus as the negative. Kodak gave me a method for using Tech Pan and TMX 100. Since I still have some SO-132, I have only slowly been moving to the 2 step method, but I have used Ortho Plus for both steps. I can't say I've mastered the technique, but the aim is for an interpos that has all the tones in it--it needs to be slightly dense & flat--it's not meant for viewing like a transparency. Then you contact this for the working neg. You can dodge, burn & crop the interpos as well...you get alot of control with this method. If you use a panchromatic film for the interpos you can filter out stains etc. as well...for 2 steps, you flop the neg for the interpos, and then contact it emulsion to emulsion for the negative..it gets confusing trying to keep it all reading right. Think of it like making an interneg from a slide.

 

SO-132 is hard to control contrast or to match the contrast of the original neg....plus the film needs to be processed just right, or it can suffer in storage...previous versions of this film, like SO339, didn't last long . We have old dupes made on it that changed density in a matter of a few years. It's the big reason why most archives & institutions quit using it years ago. SO-132 was supposed to have been improved, but it didn't match up with old negs very well, so not alot of people were actually using it....when commercial labs went over to digital for duplicating, the market just dried up....you can still find it though. It's about $140+ for 25 sheets of 8x10. A 4x5, 25 sheet box is about $40-50. With S0-132, you go emulsion to emulsion...

 

 

Hope this helps somewhat, Kodak has a book called "Copying and Duplicating in B&W and Color" that is still the best text out there on this stuff. My opinions only.

Check out the article in Ed Buffaloes unblinking eye site on how to make direct positives from ortho film. If this does not work for you then I dont know what will, seems to me the best way to make duplicate enlarged negatives. <a href="http://www.unblinkingeye.com">link</a>

Well, why couldn't you just use sheet dupe film and E6 then?

Has anyone used the dr5 chrome process? That might be another alternative to Scala. I'd be surprised if no one had asked them about enlarging dr5 chromes to get enlarged negatives.

 

http://www.dr5.com/main.html