Στις 22/2/2020 1:53 Ï€.μ., ο Ken Hart Î*γÏ�αψε:
On 2/21/20 3:13 PM, John Floren wrote:
Anyone got tips for printing color negatives (Portra 400 120 format, in
this case) on B&W photo paper? I don't have a color enlarger, but I'd
like to make some prints. Thought I ought to poll for suggestions before
I start fooling around wasting paper.

john


It was difficult years ago, and it's probably more difficult now!

First, you don't really need a color enlarger to print on B&W paper.
What you need is some of the long-ago discontinued Kodak Panalure paper.
Panalure paper was sensitive to nearly all colors of the spectrum, so
that color negatives would reproduce better. Standard B&W paper has low
sensitivity in the red area, so the tones are going to be off.

(If you find someone selling Panalure paper on eBay, it has probably
long ago expired.)

Second, the color mask of color negatives (the overall orange color)
will make the color negative nearly invisible to the b&w paper, so your
exposure times will be long. And color paper has higher contrast than
b&w paper, so you are going to need a high contrast grade. This will
also increase your exposure time.

If you just need a proof print, use a #4 or 5 contrast filter, and an
exposure maybe 6 times as long as usual, and print like any other b&w
negative, being aware that it might not be perfect.

If you need a print with proper tonal rendition, an internegative is
probably your best route. Or a digital solution.

right panalure was panchromatic, while standard B&W paper has a common
emulsion, sensitive only to blue (thus the red safelight filter). there
was another kind of emulsion, called orthochromatic *sensitive to blue
and green8there were also infrared, sesitive to x rays etc.