A foolish idea? Creating a positive transparency from a negative

[bashful]

Idly wondering...

If I have a 4x5 negative, can I create a 4x5 positive transparency from it by simply laying it on another piece of 4x5 and exposing it with room light? Without iterating through a lot of sheets, I wonder how I would get a ballpark exposure time?

[Gary Beasley]

It would work with the right film. You might try for some ortho copy film so you can develop by inspection plus the lower speed of the film makes for an easier time finding the right exposure which even then would be pretty darn short with room light.

[koraks]

Timing exposure with room light will be impossible with regular film. With ortho film it will be extremely challenging still. Under an enlarger with a timer it's perfectly doable with slow/ortho film, and feasible with normal film although you'll have to stop down lots.

[Jim Jones]

Normal negatives have far less contrast than prints. To make a positive that will look good when projected on a screen or displayed on a light box, high contrast film should be used for the positive. Tech Pan was good for this. When exposed in a camera instead of contact printed, a light meter will give a starting point for the correct exposure after allowing for bellows extension.

[maltfalc]

a single low wattage bulb that evenly illuminates your work surface high above the negatives would be better. one of these will help you figure out exposure times if you don't want to do a bunch of test strips.
215425

you could also try metering at f/1 and the second negative's iso with a highlight area of your original negative above the meter to get a ballpark starting point.

[martiansea]

I've had good luck making positives using this film:
https://www.freestylephoto.biz/531345-Arista-Ortho-Litho-Film-3.0-3.9x4.9-50-Sheets-For-4x5-Film-Holders
I used one of those old contact printer things, that has the light bulbs inside and the clamp down top. Was fairly easy to find a good exposure time. Developed in Dektol that was already out in a tray for developing paper, and the tonality wasn't bad.

[Drew Wiley]

I often do it. I use one of my enlargers as the highly predictable and precisely-timed light source, along with a pin-registered contact printing frame.

[FrancisF]

I have tried contacting printing a negative, FP4, on FP4 for a b&w transparency...without much success.

Using the Photography Formulary reveral kit for TMax, I had great success in 4 x 5. Encourges me to go bigger.

[Tin Can]

Bashful

Last chance

Copying negs is easy until you want perfection, use paper clips and moon light

Here is a progression of your plan

I first shot a light bulb and made a print, that I hung on my wall for a year while I considered it

The neg was any old film, in this case X-Ray cut to 5X7, I enlarged onto 11X14 paper

But after a year I decided to copy the original 5X7 onto 4X5 Fp4, also called a interpositive neg

I printed it making a negative paper print,

Much better finished image

The enlarger was never needed, could have done it with a piece of window glass

BTW, my first time, I was learning as I worked

The trick is to just do something, even if it is wrong, we need to protect our phony baloney jobs

That's a line from one of my favorite movies

Cheers

https://live.staticflickr.com/65535/51152090424_61022e9893_b.jpg (https://flic.kr/p/2kW8Qnw)Atomic Bomb (https://flic.kr/p/2kW8Qnw) by TIN CAN COLLEGE (https://www.flickr.com/photos/tincancollege/), on Flickr

[Greg]

Many years ago did this when getting my MFA (one of several projects that I pursued). At the time used Kodak 2566 Reproduction film (Kodalith?, my memory fails me here) and developed it in a diluted D-19 (sorry don't remember the dilution but may have been 1:1). They were enlargements which fit inside the panes of a window. Biggest problem was enlarging dust on the glass carrier. In the end used a glassless film carrier with the film tensioned flat with tape on all 4 sides. The 2566 film had an expiration date on its box of the mid 1980s but worked just fine. Still use one 11x14 box of 2566 to test my lenses except now developed in diluted Rodinal 1:50. FYI: Personally have had a lot more luck using (very expired) 2566 than with shooting/using X-Ray film. 2566 film is a lot, I mean a lot more scratch resistant than X-Ray film in my experience, and expired 2566 film actually to be had for less of the cost of "new" X-Ray film.

[Tin Can]

I also covered my windows with 4 sheets of 14x17 inch x ray positive backlit for pedestrian night viewing

[FrancisF]

I have tried contacting printing a negative, FP4, on FP4 for a b&w transparency...without much success.

Using the Photography Formulary reveral kit for TMax, I had great success in 4 x 5. Encourges me to go bigger.

215454

[bashful]

Thank you all for the input! As I suspected, there's a great deal more to this than I realized.