Topic: A question about grain

[Nigel]

This may be obvious to some but why do some shots have more pronounced grain than others? I've always assumed it had to be scanning related, but is that the whole answer?

This is a 100% crop from two frames on the same roll. So (obviously) the same film (tri-x @1600), developed in the same chemicals (hc-110b), for the same time and scanned on the same scanner - both at standard auto conditions.

So why is the grain so different?

Here's a link to download the original if you're interested: https://www.dropbox.com/s/oo2e56i5246s4kg/100%25.jpg?dl=0

[kentish cob]

Have pondered the same thing on occasion, without really coming up with an answer.

Based on no knowledge whatsoever, I wonder whether it may be more noticeable on negs with large areas of fairly even tone... in the absence of anything "substantially contrasty" maybe the scanner is focussing on the grain rather than the image?

Obviously, there's contrast between the sculpture and the wall, but maybe the scanner found focus on the even tone of the wall before it reached the detail?

[Bryan]

I’ve noticed the same thing in large areas especially in the sky.  I’ve also noticed that the more post processing I do in an image, especially when I’m compensating for exposure problems, it brings out the grain more.  The photos below were taken on the same roll of film in the same location minutes apart with identical exposures.  The biggest difference is the direction the camera was pointing, East in the Shasta photo and South in the power pole photo.  They were both scanned with a digital camera. 

Mount Shasta by Bryan Chernick, on Flickr

Failing Infrastructure by Bryan Chernick, on Flickr

[Francois]

You're right in that grain is always more visible in even areas. But to that question the answer is more of a multiple choice question.
First, the area being more even, there is less contrast difference which makes the grain more easily seen.
But the biggest problem comes from scanning. Here there are two problems that combine to make things worse. First there is the randomness of the film grain which then combined with the grid from the scanner tends to make it appear bigger. And then there is the sharpening we must add to the scans to compensate for the slightly out of focusness that flatbeds introduce...

So, there you have it... At least my 2¢ worth in this case.
I just hope my sleepless brain managed to babble something that isn't just nonsense.

[Pete_R]

All of the above but, also, the exposure and contrast of each image will cause the scanner to use different settings to scan each and that can cause the grain to be more obvious in one than another. If you scan both frames with identical scan settings (which will probably mean using manual settings rather than auto) then they should be more similar, at least in terms of grain.

[cs1]

Have you ever observed that grain also appears to be really pronounced when using a red filter? It always strikes me as odd. I always thought that using a red filter shouldn't have any influence on the overall grain when using panchromatic film. It reduces the light by some stops but that should be it.

[Nigel]

Thanks guys. I'm glad it's not just me.

Although it's right that grain is more noticeable in the large areas of a single tone there is definitely more grain in some frames with a similar amount of detail.

Next time I get the scanner out I'll rescan those two frames on a full manual mode and see if that reduces the difference between them.

[Francois]

Strangely, I don't think it will do much...
Unless you scan without sharpening and then apply a sharpening algorithm other than the unsharp mask all scanners use...

[Nigel]

I can't remember quite why now but I generally scan with the unsharp mask turned off. 

[mcduff]

I have noticed this too but I agree with Peter and Bryan that is it likely how the tonal curve is getting adjusted (whether automatically when we scan, or after the fact).

[MacArron]

Have you ever observed that grain also appears to be really pronounced when using a red filter? It always strikes me as odd. I always thought that using a red filter shouldn't have any influence on the overall grain when using panchromatic film. It reduces the light by some stops but that should be it.

I have. I do not know the reason, but using a red filter or even a polarizer brings up lots of grain and the image turns out to be useless every time. To solve this I don't use these filters anymore    But I'd be happy to know the reason...

[cs1]

I found that orange filters yield good results in terms of dramatic clouds and good contrast but I have the impression that the grain is not as pronounced as with a red filter. This is also odd because my darkest orange filter and red filter both reduce light by the same amount of stops (if I remember correctly) but produce quite different grain. To quote Winston Churchill: It's a riddle, wrapped in a mystery, inside an enigma.

[Francois]

Red filters increase contrast more than orange. That means darker skies, which is less light hitting the negative. Any time you're riding on the edge of what the film will support exposure wise, you will get more uneven grain. I also know it has something to do with the speed the developer processes different parts of the film but going that far is on the limits of what I know.

The red and orange filters might have similar exposure compensation, but that's for an average scene with average contrast. Shooting a field of grass with no sky visible would be very underexposed with a red filter even if you apply the recommended compensation.

[Faintandfuzzy]

While it may be on the same roll....different exposure for the scene between photos can change apparent grain. 

[cs1]

I stopped using a red filter due to the very pronounced grain. The explanation with the extreme differences in exposure makes sense to me. On top of that the missing light frequencies might have an influence on the grain as well. But that's just wild guessing. Maybe there's a fellow filmwaster who's not as challenged as me in the field of chemistry / physics who can shed more light on this.

[Francois]

It's not really related to the light color frequency since it's panchro film.
It's just that different parts of the negative get developed at different speeds during the process.
And the longer it stays in the developer, the more pronounced the grain.

That's why some people like Mortensen tried stand development in the fridge. This gave him very fine grain... but took about 12 hours to get results!

That's also why there are fine grain developers. They tend to minimize the size of the grain, but often at the expense of film sensitivity.
One of the classics for cheap fairly fine grain is good old D-76. It's not the finest grain developer but it's easy to find and pretty cheap.