Is filtration even for each frame of a given film?

[zehner21]

The question arises because I'm printing some frames of an Ultramax 400, developed at home and I found that I have to adjust the filtration for each photo.
I though that filtration, once found the correct combination of CMY, was even across the entire film; yet, I have to adjust it and, sometimes, it requires a heavy adjustment. Film was shot during an entire day.

Thanks

 

[tanner]

If you have different color temperature in different frames and you're trying to achieve true white on the paper you'd have to adjust the filtration accordingly. I'm guessing that's what you've been doing. As with other aspects of photography, color is quite subjective

 

[cliveh]

It should be similar. Did you have a great variation in exposure and/or lighting?

 

[zehner21]

It should be similar. Did you have a great variation in exposure and/or lighting?

No, f-stops and seconds are always the same... It's incredible!
But, it happens that sometimes I have to add up to 20cc of yellow.
I guess that this is due to the different color temperatures...
Well, thank you guys!



Edit: ops! I read it wrong! Sorry... Yes, light has changed because I started in the morning and finished around 6 p.m.

 

[David Lyga]

Cagliari, Sassari, or Alghero? (was there in 1968 and 1970)

I have to comment on this: zehner21, there have been many times in the past that I have experienced the same. I think few realize that the time, temp, and agitation of the print can at least somewhat change the hues, thus seemingly mandate filtration adjustment.

One wonders if your need to change a particular negative's filtration is consistent, in that repeated attempts at printing that particular negative require the SAME filtration as previously. I wish I could say more.

Yes, your hasty 'edit' changes matters profoundly. There is a major difference between noon daylight and late afternoon or morning daylight. Much warmer. - David Lyga

 

[lhalcong]

This brings an interesting point. A Mini-lab automated machine will not adjust the filtration for every frame ? correct. ? I don't even know how an automated machine can come up with the correct filtration in the first place, but once found , exposure and filtration will be consistent throughout the roll. so for those 4x6 prints, what was wrong stays wrong . Am I correct ? Can someone with experience elaborate on this.

 

[MattKing]

This brings an interesting point. A Mini-lab automated machine will not adjust the filtration for every frame ? correct. ? I don't even know how an automated machine can come up with the correct filtration in the first place, but once found , exposure and filtration will be consistent throughout the roll. so for those 4x6 prints, what was wrong stays wrong . Am I correct ? Can someone with experience elaborate on this.

Most minilab machines use a type of automatic exposure that responds to each frame. That is why they have a lot of problem with unusually coloured backgrounds.

Minilabs require operators. Good operators know how to compensate for the automatic systems in the minilabs.

I ran a Durst quasi-minilab for a couple of years. It had a test-print mode, which did automated test prints of each negative, and printed the exposure information on the back of each test. I would take the tests, mark needed corrections on each, and then print in full each negative with the corrections added to the automatic exposure chosen by the machine. Normally, I would have to do very few re-prints.

 

[Mr Bill]

This brings an interesting point. A Mini-lab automated machine will not adjust the filtration for every frame ? correct. ?

Hi, not correct. A mini-lab printer DOES adjust for every frame.

I don't even know how an automated machine can come up with the correct filtration in the first place, ...

Early mini-lab machines typically had three color sensors somewhere after the negative, so they could measure the average amount of light (and color) coming through the negative. They would change both the exposure time and the filtration in an attempt to get a roughly grey average. This is similar to the way we use a light meter to measure exposure for an outdoor scene, and the earlier mini-labs were easily fooled in the same ways. If you took photos outdoors in the snow, the mini-lab printer would want to print it too dark; it was up to the operator to notice this possible problem, and override the machine by pressing the appropriate density or color buttons.

Different types of film had different characteristics, so the machines were pre-calibrated for specific film types. This was done with the assistance of printer setup negatives (often called "Shirleys") which were available on different films. The results were saved on a "channel," and it was always necessary to select the proper channel for the customer's film type.

Printing errors due to "non-average" negatives was an ongoing problem with such printers until Agfa came out with their "MSC" mini-lab, incorporating the first (to my knowledge) built in scanner. Although the scanner was low resolution, it was the first time such machines could be "smart" about the scene content, and adjust accordingly. They were a bit like today's advanced "matrix metering" cameras, compared to an averaging meter.

 

[RPC]

I operated a minilab printer years ago and the above posts reflect my experiences. I have always shaken my head whenever I have seen posts of those who sent their film to a lab and ask for prints with "no corrections" because they thought such prints would better show how they are shooting or didn't want anybody messing with the color. Such requests are invalid, of course. There will always be a correction on a print from a color negative, either by machine, operator, or both.

 

[randyB]

minilab systems

Hi, not correct. A mini-lab printer DOES adjust for every frame.

Early mini-lab machines typically had three color sensors somewhere after the negative, so they could measure the average amount of light (and color) coming through the negative. They would change both the exposure time and the filtration in an attempt to get a roughly grey average. This is similar to the way we use a light meter to measure exposure for an outdoor scene, and the earlier mini-labs were easily fooled in the same ways. If you took photos outdoors in the snow, the mini-lab printer would want to print it too dark; it was up to the operator to notice this possible problem, and override the machine by pressing the appropriate density or color buttons.

Different types of film had different characteristics, so the machines were pre-calibrated for specific film types. This was done with the assistance of printer setup negatives (often called "Shirleys") which were available on different films. The results were saved on a "channel," and it was always necessary to select the proper channel for the customer's film type.

Printing errors due to "non-average" negatives was an ongoing problem with such printers until Agfa came out with their "MSC" mini-lab, incorporating the first (to my knowledge) built in scanner. Although the scanner was low resolution, it was the first time such machines could be "smart" about the scene content, and adjust accordingly. They were a bit like today's advanced "matrix metering" cameras, compared to an averaging meter.

Quite correct Mr. Bill. In the 80's and early 90's I operated a Noritsu system that was state of the art at the time. Each morning when I turned on the equipment I had to "warm-up" the lamp and the chemicals, then print the Master channel neg, read it on the densitometer and enter the corrections for the Master, then I did the same thing for the different film type standard negs, Kodak, Fuji, Agfa, 3M, etc. Most of the changes are from the bulb aging but some corrections came for the change in the chemistry from the volume of film run thur. Of course when you changed bulbs you had to redo everything all over. Occasionally we would do a complete dump of the chemicals and start with a fresh mixed batch which meant recalibrating everything again. An experienced mini-lab printer is a very special person, while the sensors corrected the color and gave a base exposure time a good printer knew how to fine tune the print with the override buttons, he/she had to look out for frames shot under tungsten light or flourscent and make adjustments, PLUS look for under/over exposed negs and correct them all while keep up production. Sometime in the 90's most of the new minilab systems became much more automated as the computer programs and associated sensors became capable. RandyB

 

[lhalcong]

How about the Machines at the Drug Stores.? Those level of details are not - were not taking in consideration in chain drug stores 1 hr. photo location. right ?
I remember getting bad pictures when I took bad pictures when I was young . nobody corrected my regular consumer pictures I sent to the drug stores for 1hr development.

 

[MattKing]

How about the Machines at the Drug Stores.? Those level of details are not - were not taking in consideration in chain drug stores 1 hr. photo location. right ?
I remember getting bad pictures when I took bad pictures when I was young . nobody corrected my regular consumer pictures I sent to the drug stores for 1hr development.

Those drug store machines were usually just about as capable as the fancier versions. The built in automatic exposure and automatic colour corrections are/were quite capable of responding to poorly exposed photographs and photographs exposed under unusual lighting conditions. However, they still required proper setup, regular callibration and maintenance, proper chemical replenishment and experienced operators. Some drug stores offered that, along with a policy that required their staff to regularly check results and reprint where required. Others ......

 

[randyB]

drug store minilab

How about the Machines at the Drug Stores.? Those level of details are not - were not taking in consideration in chain drug stores 1 hr. photo location. right ?
I remember getting bad pictures when I took bad pictures when I was young . nobody corrected my regular consumer pictures I sent to the drug stores for 1hr development.

First off you have to have an operator that actually has a clue as to what he/she is doing, THEN they have to care to do a good job. Many times the person behind the photo counter has only the very minimum instructions on how to operate the equipment, plus the photo dept may not be their main job in the store, they were put there because Joe/Susie didn't show up for work. Now-a-days quality control is very hard to find. One other question!!!!, were you expecting good photos to be made from the bad pictures that you took? An experienced Tech can only do so much tweaking of the print.

 

[Xmas]

But you will need a different white balance frame to frame.
Direct sun is yellow sky is blue.
Movie lights man would have colour temp meter and big box of balance (cc) filters.

 

[DREW WILEY]

As color neg films get more saturated or contrasty, the more sensitive they are to changes in Kelvin color temp. So even on the same roll it's entirely possible to get different results. You'd have to compare this to a standardized control taken in strict studio parameters with a color temp meter, if developer (C41) process variance is what you're concerned with. It's more likely a lighting variance, scene to scene. Not all films were engineered with the same kind of "blaaah" extreme latitude as what we conventionally expect from amateur films. To get more "snap" to saturated colors, some of that latitude has to be sacrificed; and in such cases, the film itself is more finicky to changes in luminance.