How does C-41 affect grain

edwardkaraa · Jun 6, 2006

Hi, I usually process my negative film either at a pro lab for important subjects or at a local Fuji lab for convenience and fast processing. I've been noticing a pattern here. Negatives from the Fuji lab have much smoother grain than those from the pro lab. Of course I still get scratch and finger-prints free negatives from the pro lab but I'm puzzled about the grain issue. Does anyone have any idea about what could possibly be the reason behind this? Thanks.

PS. I use regular Fujifilm Superia 100 and 400.

Dave Parker · Jun 6, 2006

Are you doing a side by side comparison on a light table between the negs from one lab to the other, the thing that I could think of is different chemistry from one lab to another or different temps in processing, if your looking at prints, then it is not a good comparison as different papers can exhibit different types of effects..

R.

edwardkaraa · Jun 6, 2006

Hi Roxi331,

Actually I'm comparing 4000 DPI scans at full size. Someone on another forum has suggested that older chemicals can produce grainier negatives. Any idea?

Dave Parker · Jun 6, 2006

Hi Edward,

The scans, are they of the same speed film? in other words ISO 100 compared to ISO 100, if your comparing different speed films, you will see a difference in the grain between the two scans, also does your scanner allow you to choose different film profiles to match the film scanned..I can't imagine old chems in shops that process much film as it is not reused in most modern processing machines, but it could be different brands of chems or temps as I was saying above, you might give them both a call or stop by and explain your interest in why one differs from the other and have them show you the process they are using.

R.

edwardkaraa · Jun 6, 2006

Roxi331 said:
The scans, are they of the same speed film? in other words ISO 100 compared to ISO 100
R.

No even worse, I'm comparing correctly exposed ISO 100 film by the pro lab to ISO 400 film by the Fuji commercial lab, and the 400 has finer grain. I'm no expert in processing but I suspect the following:

a. pro lab has not so much activity and uses not so frech chemicals.
b. pro lab could be using Kodak chemicals. Fuji chemicals might give slightly better results with Fuji films???
c. pro lab using some sort of manual processing which gives more grain (more agitation)?
d. I have no clue what I'm talking about.....

jhavard · Jun 6, 2006

edwardkaraa said:
No even worse, I'm comparing correctly exposed ISO 100 film by the pro lab to ISO 400 film by the Fuji commercial lab, and the 400 has finer grain.

That's a bit like comparing apples and orange-colored baseballs.

In other words, test the same type of film, preferably from the same batch. There are some new films out that have finer grain at ISO 400 than the older versions at ISO 100.

Dave Parker · Jun 6, 2006

Edward,

it is really hard to compare different speed films and such done by different labs, I would suggest shooting two rolls of ISO 100 then have one done by your pro lab and one done by the commercial lab, that way we have a basis for direct comparison.

R.

Photo Engineer · Jun 6, 2006

C41, if run properly and in control, should give the same grain for the same film.

If the process is out of control, the crossover and color shifts should be bad enough that you would be annoyed by them as well as any change in sharpness and grain.

PE

bob100684 · Jun 23, 2006

edwardkaraa said:
No even worse, I'm comparing correctly exposed ISO 100 film by the pro lab to ISO 400 film by the Fuji commercial lab, and the 400 has finer grain. I'm no expert in processing but I suspect the following:

a. pro lab has not so much activity and uses not so frech chemicals.
b. pro lab could be using Kodak chemicals. Fuji chemicals might give slightly better results with Fuji films???
c. pro lab using some sort of manual processing which gives more grain (more agitation)?
d. I have no clue what I'm talking about.....

option d. some 400 speed films have finer grains than some 100 speed films.
Examples kodak 100 a consumer film.... has a pgi at a print size of 4x6 of 45
kodak portra 400nc has a pgi of 44
kodak ultra color 400 has a pgi of 40
kodak high def 400 has a pgi of 39
kodak pgi, lower numbers=les grain

on the fuji side
fuji "true definition" 400 has a difuse RMS granularity of 5
fuji reala, 100iso, has a difuse RMS granularity of 4
the thing is a difference of one on that scale means almost nothing, a more contrasty film may have more apparent grain than a film with lower grain but more contrast. Also maybe your scanner focused better on the 100 iso film for some reason yielding a sharper grain...or somehow your scan is more sharpened

Photo Engineer · Jun 24, 2006

After thinking this over, I feel that the problem is silver retention. Retained silver in negative films will lead to desaturated color and higher grain.

You can check this out and verify it by bleaching the film, washing, fixing, washing and re-stabilzing the suspect film according to C41 specifications.

PE

Claire Senft · Jun 24, 2006

Perhaps you should take the grainier negatives back to the pro-lab and tell them that you suspect retained silver and have them re-bleach the negatives.

bob100684 · Jun 26, 2006

another option for answer D. Fuji lab=scanning on frontier with a shitload of grain reduction, pro lab scanning on something or even a frontier w/o grain reduction software running

Stack8 · Jul 5, 2006

PE is right. Time , Temp, Replen rate, and agitation, and will affect grain. I'ts all about process control.

Samuel B · Jul 5, 2006

There can be quite a bit of variation betwwen different labs, and these days with the lower volumes of film being processed it can be more of a challenge to keep the process in control, and I suspect many labs just don't see it as that important any more, unfortunately. Some labs like to have their process a bit "high", that is a bit over-developed for more "gutsy" negatives. I printed some wedding photos for a photographer the other day which appeared to be way over developed, really contrasty, grainy & yuk.

But for a fair comparison you really need to compare using the same film.

How does C-41 affect grain

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