Topic: the size of grain .... ?

[Nigel]

Do you ever post a question thinking that there's probably an blindingly obvious answer that you've overlooked and everyone else will shout "Duh!". Well this is one of those.

I've noticed when shooting in low light situations that the 'apparent' size of grain can vary on a single film. I recently went to a friend's wedding where the official photographer was apparently a bit spooked by the fact that my friend was the curator of a photography gallery and so specified a point-and-shoot camera only policy! Which I can understand to some extent but you do wonder who was the customer in that situation.

Anyway, so there I was with my little Olympus p&s loaded with some Neopan 1600. This is processed in Rodinal which I understand is not recommended for high speed film, but I would have expected the film to be equally grainy all the way through. I don't know how clear it'll be from the 100% sections below but some shots are significantly grainier than others.  

The first shot had a window at high level giving some back lighting so the faces were a little underexposed. The second is at 90 deg to the light so probably more accurately metered. This is the only difference I can think but would that make such a difference.

I'll post the original untouched negs below.

I'd really appreciate your thoughts.

[LT]

I'll hazard a guess at 2 things:

these are neg scans;

&

the grainy negs are under exposed.

It's likely to be the scanner software compensating for the lack of contrast in the under exposed negs by adding loads of extra contrast, which increases the graininess loads.

 

[Dave Elden]

I've noticed when shooting in low light situations that the 'apparent' size of grain can vary on a single film.

The size of grain in the developed film will be a function of several factors but one of them is exposure; more exposure = bigger grains.  So the apparent garin size will vary on a negative with the subject brightness.  You commonly see this burning in a featureless area of sky when printing from a 35mm neg, often this area will print with some tone when burned in but will be more grainy than the rest of the picture.  Thsi is because it had a few stops more exposure.  This increase in grain (and loss of sharpness) is a reason to avoid major overexposure especially using small format film.
Hope that helps.

[fwank]

also looks like some jpeg compression increasing the grain effect.  the other day i noticed my scanner was using jpeg comression even though i was saving in tiff.

[sapata]

I've noticed when shooting in low light situations that the 'apparent' size of grain can vary on a single film.

The size of grain in the developed film will be a function of several factors but one of them is exposure; more exposure = bigger grains.  So the apparent garin size will vary on a negative with the subject brightness.  You commonly see this burning in a featureless area of sky when printing from a 35mm neg, often this area will print with some tone when burned in but will be more grainy than the rest of the picture.  Thsi is because it had a few stops more exposure.  This increase in grain (and loss of sharpness) is a reason to avoid major overexposure especially using small format film.
Hope that helps.

Thanks for that ! I never really understood why the sky on my 35mm negs were so grainy comparing to the other areas of the neg...

[Francois]

One thing's for sure, scanning a B&W negative always increases the appearance of the grain. It has to do with the fact that the grain is positioned in a chaotic manner while the pixels are perfectly aligned. Think of it a bit like when you connect a camcorder to a television and shoot the screen to make one of those feedback loops. Every image gets more and more crooked even though you hold the camera as straight as possible... it's about the same thing.

As for the grain, it's always more visible in regions that are mid-gray.

Also, processing has a lot to do with it. The more you push the film, the bigger the grain will be. Thing is you're developing grains which have only received minimal exposure. This will raise the image contrast and cause a visual clumping effect.

[Pete_R]

What sort of development did you use? Stand or partial stand maybe?

I'm just thinking that the obvious difference is the second neg has received more exposure (is brighter) and would be a denser neg so development would stop sooner whereas the less dense neg would develop for longer.

This is pure guesswork on my part that it might make a difference.

[Nigel]

Thank you for all your responses.

Peter - no in this case it was a standard timed development in Rodinal 1+50, which from memory was 8 mins.

Well at least I understand that my simplistic view, that all the film should look the same, is not correct.

Francois - thanks for your explanation regarding the effects of scanning.

I've gone through a long period where I've really taken pleasure in the noticeable grain, but of late I've been looking at small grain b+w images and really liked them. I didn't have any choice but to use high speed film in this instance. It was quite dark inside and I didn't want to use a flash during the service. But I think I'm going to start playing with some slower speed film and maybe investigate a developer that has a less pronounced effect on the grain.

Again it's amazing the breadth of knowledge on the forum.

thanks for your help. Nigel.

[Francois]

I forgot to mention that the only scanners who don't exhibit such artifacts are the old laser based drum scanners... but since nobody I know has enough spare change to go out and get one of these, there's practically no need to mention it

[Pete_R]

I found this which explains the aliasing quite well.

http://www.photoscientia.co.uk/Grain.htm

[Nigel]

Thanks Peter, that is really interesting although it doesn't give the 'magic bullet' answer we'd really like.

(Do you think he put it on a really grainy,difficult to read, background just to make his point.)