8x10 vs 11x14 exposure question

I have been using my 8x10 to make contact prints from black and white negatives for a while now. I have a reliable process that produces results that I am happy with.

Now the puzzling part for me and the reason for writing this post.

I borrowed my friends 11x14 camera for the week and I used the same sheet film (Ilford HP5+) and developer (Ilford DD-X) and Paper (Ilford MG-IV) and I used my same meter, etc. I did everything the exact same way on the 11x14 as I do on my 8x10. Literally everything the same. The only difference is the size of the sheet film.

I found that the negatives that I created were much thinner than my 8x10 negatives (created much darker contact prints at my normal proofing time). Logic tells me that the 11x14 requires more exposure than the 8x10 for the exact same variables?

But I am thinking, how can this be because light is light and it shouldn't matter if the film surface is 8x10 vs 11x14.

Once I get this straighted out, I wil go do some more tests putting the 8x10 and 11x14 side by side.

Thanks in advance.

Are you using the same lens/shutter on both cameras? Same shutter speed? Same aperture?

Right. I'll bet the other camera had a shutter running at different speeds that yours, no matter if they were at the same settings.

I'll bet it was same lens BUT for same subject the bigger format will allow you to get closer and that means less lens extension which means brighter/denser negatives.

Are we having a sweepstake on this?

You realize a lens at f-11 on an 8x10 will produce the same amount light as another lens at f-11 on an 11x14.

So if you are using different lenses at the same f-stop I would question the speed of one of the shutters.

If you are using the same lens on both cameras with identical image size and identical metering, then I got no suggestions.

maybe it was your bellows being extended out further.

Yes I am.

shutterfinger said:

Are you using the same lens/shutter on both cameras? Same shutter speed? Same aperture?

Click to expand...

Lots of variables that could change things.

Different film lot
Different film expiration dates
Different film storage methods
Different lens
Different shutter
Different aperture
Different shutter speed
Different meter
Different developing time
Different developer strength
etc,
etc,
etc.

It sounds like you have worked through some of them. If you keep trying you will probably come across the reason. Or maybe not. This is what makes our craft so much fun, while being so frustrating at the same time.

My question was basically answered. It should be the same as long as all the variables are the same. I suspect a shutter problem at this point. Thanks for the help and now I will go confirm with testing.

There's probably noticeably more light fall-off with 11x14 at the edges/corners when using the same lens at the same distance. So any small decrease in overall exposure, for whatever reason, will be exacerbated at the extremes.

I read the question twice and still got it the wrong way round now that I read it again. I think I'm having a major senior moment today. (not much different to every other day these days.)

analog65 said:

Logic tells me that the 11x14 requires more exposure than the 8x10 for the exact same variables?

Click to expand...

Yes that is true. Except for infinity focus, however.
You don't say if you were at infinity focus, so you may or may not be correct with you logic.

Either way, observation of the appropriate bellows factor during large format photography would be prudent.

Are you doing table top still life? If your framing the same subject with 8x10 and 11 x14 then your going to be closer with the 11x14 and therefore may introduce bellow extension factors.

Bigger neg requires more developer, therefore, possibly developer exhaustion.

All very helpful thoughts. I am going to do some testing this coming week and narrow down the variables to verify the source.