During my last printing session, while trying to find the good exposure time for my prints, I faced a weird situation about the needed exposure time.

When setting my enlarger opening at f/8 or f/11, I usualy have needed exposure times between 10 seconds and 30 seconds. This time it was way much shorter:

  • while exposing only 1 second the photo was not enough printed (the final photo is way too white)
  • while exposing 2 seconds the paper was almost burned (the final photo is way too dark)
  • so I narrowed the enlarger opening to f/16, and then the good exposure time was a bit less than 3 seconds to have a correct print.

In the end I have some correct prints, but I'm very surprised of this very short exposure time.

What could explain such a small needed exposure time ?

For the context & the technical details:

  • I used the same enlarger, paper (multigrade) & filter as when I usualy have between 10 & 30sec of needed exposure time
  • The photo were taken outdoor, on a sunny summer day
  • The film is a Kodak 400TX. First time I use this film, is it known to be "short to print" ?
  • I developped the film myself. Could the film itself be not enough developped ?
  • The paper developper is Ilford Multigrade, which bottle is opened since ~2 years (kept well closed in a dry & not hot place). Could this aged developper be "more powerful" and explains this very short exposure time ?
  • \$\begingroup\$ Something here is very wrong. The Sunny 16 rule says that your exposure time for ISO 400 film on a sunny day at f/16 should be about 1/400s, nothing like 3s. \$\endgroup\$
    – Philip Kendall
    Feb 6, 2023 at 18:30
  • 4
    \$\begingroup\$ Maybe there's a confusion here: I'm talking of the exposure time & apperture of the enlarger, during the print session, not during the photo shoot. These photos were shooted at around 1/500s \$\endgroup\$
    – Pierre
    Feb 6, 2023 at 19:08

1 Answer 1


Most likely, the film was underexposed and or underdeveloped. You should examine your negatives to make this diagnosis.

Other possibilities – the enlarger lens was operating at near maximum diameter (aperture) and you did not catch it.

The enlarger lamp if an ordinary tungsten filament bulb nearing the end of its life cycle. Sometimes, the filament breaks and then re-welds making the filament shorter. Such happenings will cause the lamp to brighten before failure.

Another possibility, the paper underwent hyper sensitization. This can happen if the paper is fogged to a low level of light. Photo materials have a threshold of exposure, this is the minimum amount needed to show some blackening. Fogged film or paper will significantly gain sensitivity to light. This can also happen if the paper is chemically exposed to chemicals like out-gassing from paint or mothballs etc.

Another possibility is voltage fluctuation. Just a few volts gain to the lamp will cause it to brighten significantly.

  • 1
    \$\begingroup\$ Thanks for pointing this. I examined the negatives, and it seems to be underdeveloped. When checking Ilford's "Common processing problems", my negatives match the "Processed negatives are too light" section. I didn't knew this could affect the enlarger exposure time to be so low. Now I know, thanks :) \$\endgroup\$
    – Pierre
    Feb 7, 2023 at 10:26

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