Film exposure accident.. Help!

Question

Yesterday I was shooting in the sea and dropped my light meter in the ocean which unfortunately immediately broke!

This led me to shoot two rolls of Portra 400 using my Pentax 67 TTL on board meter.

Mistakenly I forgot to change the meter from 160 to 400.

While using Pentax TTL meter I usually shoot in the plus as I am a little superstitious and don’t trust the exposure.

So… When I go to develop my film do I push it 1 stop as I rated it at 160? Would this mean that the film is +1 stop as I am technically pushing it two stops bearing in mind I over expose it on the TTL Meter?

Answer 1

So, you overexposed your film by 1 1/3 stops (if you're actually exposing for ASA 160, you hint at actually exposing for a slower speed). As this isn't a whole lot, there are two things you can do:

1. Process the film as normal. Overexposing colour negative film, especially Portra, is done regularly and its results are widely regarded as pleasant. Expect more pastel, washed out colours. Check this source for some examples of overexposed Portra.
2. Pull process the film. Push processing is the act of underexposing film, and then increasing the development time to still get proper density. In this case you overexposed the film by exposing the film as if it was less sensitive to light, so shortening the development time would here correct for the otherwise too dense film base. Pull processing will generally produce less contrast and reduced grain.

Which option you choose is up to you, but both will naturally result in different results than those you are used to when shooting Portra 400 at box speed.

Answer 2

So… When I go to develop my film do I push it 1 stop as I rated it at 160? Would this mean that the film is +1 stop as I am technically pushing it two stops bearing in mind I over expose it on the TTL Meter?

You didn't "rate the film at 160". You calibrated your camera's meter for 160, even though you used 400 film.

Using the 160 meter setting with 400 film doesn't magically change the film to 160. The film is still 400. Your camera's meter, however, thinks there is 160 film in the camera so will recommend too much exposure and your film will be overexposed.

The last thing you want to do with overexposed film is push the processing, unless you're going for some really ethereal, almost all white effect. Push processing is for underexposed film. Instead, you probably want to pull the development. Your meter was calibrated to expose your film 1 1/3 stops too bright. You then exposed even a bit brighter than that. So use the film manufacturer's data sheets to under develop by 1 1/3 stops plus whatever additional exposure compensation you used.