OverExposing Color Negative, Decreased Grain

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I've read in various forums that when shooting color negative, in particular, Portra 160 NC, if you overexpose (i.e. shoot it at 100 ASA vs. 160 ASA), then you'll get less grain. For those who have used this technique, I assume you just develop normally rather than push processing it?

-- Howard Slavitt (info@enaturephoto.com), February 10, 2002


You do develop normally. I often question whether this is really "overexposing" since most of the modern negative films seem very thin when exposed "normally". I suspect that most people improperly meter and expose for negative film to begin with (how many of us have seen newcomer's B&W negatives that have benn hopelessly underexposed?), and by dropping the ISO it just gets them back in the ballpark. The result isn't so much a decrease in grain with overexposure but the avoidance of an increase in grain with underexposure. Some, such as the old Kodak Vericolor, were genuinely overrated to begin with. Lab sensitometry test results often have to be adjusted for real world conditions.

-- Wayne DeWitt (wdewitt@snip.net), February 10, 2002.

Hi Howard

It is better to overexpose the neg. films especially if you want scans out of it. But I rate them at 125 ASA for thad! With just normal development, not pull and push. I think you meant pull not push but it isn`t needed! I rate it only 100 ASA if I really want make high key!!!

Good luck!

-- Armin Seeholzer (armin.seeholzer@smile.ch), February 10, 2002.

May I ask how it is possible to have better scans from a dense neg ? I've been producing merely thin negs just for scanning reasons, but it is true that the custom labs here have problems to make correct scans. It is also nearly impossible to get 8x10 colornegs developed uniformly. The film is too wide for the nitrogen bursts in dip and dunk machines. Anyone know about some easy way to develope C-41 self ? Thanks, Jan

-- Jan (jan.eerala@itameri.net), February 10, 2002.


The Jobo Expert drums are well known for their uniform development. I have been using them with 4x5 negs, and I have had no problems. I do monitor uniformity from time to time with my densitrometer. I am about to start doing 4x10s which is still not 8x10, but I have heard others say the development for 8x10 was also very good.

-- Stephen Willard (willard@peakpeak.com), February 10, 2002.

Portra 160NC doesn't have a true rating of 160 anyway, it's much closer to 100 ISO. Even Kodak's own published curves show that it's actually slower than profoto 100, which it closely resembles in contrast.
DON'T push process C41 if you want any semblance of image quality. It just increases grain and blows out the highlights.

-- Pete Andrews (p.l.andrews@bham.ac.uk), February 11, 2002.

A long time ago, Kodak admitted that its color neg films were rated according to the ISO standard which may result in less exposure than is needed for many practical applications. The moral is to test your film, meter, shutters, etc. to be sure you know how everything will behave when you just have to get it right. But to the question, the color film process replaces the silver crystal that detected the light with a dye cloud. The more dye clouds, the lower the apparent grain as their effect tends to average out. However, this benefit is usually at the expense of reduced apparent sharpness.

-- Andy Eads (aceads@3-cites.com), February 11, 2002.

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