Brief Scenes

What if I used 400 IS0 speed film in a camera set to 100 ISO speed?

I have a Pentax k1000, and I was in a hurry to get pictures before the sun set. I forgot that I left my speed set to 100 ISO.
no I don’t have auto

Your film is overexposed by two stops. What you do now is determined by the film type.

If it’s transparency film, you’re a bit stuck. You can ask the processor to pull-process 2 stops but your colour balance and general image quality will be noticeably affected.

If it’s colour neg film, pull-process 1 stop, effectively producing a 1-stop overexposed film. Colour negs will give acceptable prints from negs 1-stop overexposed.

Same applies to traditional b&w. If you do your own printing, you may have to use a harder grade paper than usual because your negs will be a little flat due to the underdevelopment.

If it’s chromogenic b&w like Ilford XP2, no problem. The exposure latitude of these films is wide enough to give printable, but dense, negs at 2 stops overexposed.

Lesson 2 – Set ISO Speed