How do you know if your lab has badly processed your C41 film

[sperera]

aside from the obvious stuff like scratches or whatever, I mean on seemingly normal looking negatives when you look at them inside their sleeves as negatives.....

 

[ozphoto]

If they look normal, then they have been processed correctly.
It is rare that you would see obvious defects - and they would be obvious to the naked eye.

You need to be slightly more specific in what you are alluding to with regard to "badly processed C41 film".

 

[sperera]

I mean is there something you notice when you reproduce them either as a print or when you scan for use in magazine etc

If they look normal, then they have been processed correctly.
It is rare that you would see obvious defects - and they would be obvious to the naked eye.

You need to be slightly more specific in what you are alluding to with regard to "badly processed C41 film".

 

[ozphoto]

In my experience as a lab manager, a correctly processed negative will give you a correct scan or print if both of these processes are performed correctly.

You can make a print too light, too dark, wrong colour balance etc, so too a scan can can have the wrong Gamma set resulting in scans that are too contrasty, not contrasty enough, wrong film selected will result in colour casts also.

Possibly the only thing I could think of that would be apparent upon printing, would be reticulation - but that would be a *extremely* rare occurrence from a lab - to the naked eye, it would look as though the film was very grainy, but when you look through a loupe, you would see that it was actually reticulation and not the film grain.

If the negs look good to your eye, have no colour casts and contrast is good - check the printing and/or scanning process. Chances are it is those that are at fault rather than the negs.

 

[perkeleellinen]

My films usually go to a reliable lab and the results are always consistent so that when I print I can use the same filter pack.

A couple of weeks back I dropped a roll off at a small photo shop in town that has a mini lab, the negs looked nice but when I went to print them I had a horrible cast. Changing lab had thrown my filter pack from 95M/85Y to 85M/80Y.

I wondered if the chemicals were nearing exhaustion.

 

[nickandre]

It's very rare to get much of anything from variances in processing. The most common one would be chemistry exhaustion. Bad developer gives you very thin negatives, bad bleach gives you desaturated contrasty prints, and bad fix will leave the negatives looking milky and opaque once dried, or else just having poor archival stability.

 

[ozphoto]

Steve,

Was it the same batch of film to the last lot you processed?

I know we had to change filtration every now and then for the films we printed if the batch number changed, and could always tell when the bulb was about to expire - the colour shifted on every brand of film we printed.

 

[perkeleellinen]

Nanette - yes it was.

I printed a neg from that mini lab next to one from a pro lab to make sure my chemistry wasn't at fault too.

 

[ozphoto]

Hmmm, that's rather interesting.
Only other thing I can think of is being affected by heat - and that you can't really tell from looking at it.
Did the pro lab say anything about it being an unusual filtration that they had to use?

 

[Stephen Frizza]

Ask the lab to show you their chemistry plots. If they aren't plotting their process at least once a day then I would be worried, secondly if their chemistry is good they wont be afraid to show you their plots.
or be direct and ask for them to run a control strip with your film and ask for their reference values that way you can know exactly what happened when your film was processed. (though understandably they may charge you for the processing of a control strip with your film). Its your film and if they are a professional lab you have a right to know exactly what they are doing to your film.

 

[Stephen Frizza]

95M/85Y to 85M/80Y

.

95M/85Y to 85M/80Y isn't that big a printing shift.(im sure im going to get shot for saying this) Now if you went from 95M/85Y to 10M/0Y/10C Ide be asking what happened!!! when you shot the films was the Light temperature metered the same for the usual films you print and the mini lab roll? was the exposure time the same for your normal negatives and the minilabs negatives? How did the contrast and colour saturation compare? Do you run control strips for your RA-4 when you print? If the shift in colour was 95M/85Y to 85M/80Y and that was the only difference I wouldn't say the mini labs C-41 was near exhaustion. At my lab I sometimes get C-41 that is processed at other labs and need to make filter corrections, I also need to make filter corrections for many other reasons such as clients not controlling the light temperature or exposure etc.....

 

[perkeleellinen]

Stephen - I suppose it wasn't a big shift, but unusual for me. But then this was the first time I took a roll to another lab and as that was the obvious variable change, I focused on that. I'll have to give it some thought and think if any other issues may have played a part. I haven't had the problem since but I've also not used that mini lab since.