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  1. #1
    dmr
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    QA-ing a mini-lab ...

    These came from a FOAF by way of our mutual friend. The FOAF now runs the photo lab at a local Wally World, and I can imagine this guy as a real stickler for quality control. He did admit that he knows of other labs which are not very meticulous in the process.

    They use Fuji Frontier equipment and do a daily QA on the machines to test the chemistry and the overall results of processing.

    The one on the left is a pre-exposed negative control strip. This is run through the negative processor before any customer jobs are done each day and it's then checked with a densitometer. The D-min and D-max should be obvious as to purpose. The HD and LD are high and low test points to verify the linearity of the processing. I'm not real clear on the Y-patch. He said something about this showing residual silver and that chemistry that's going bad will show up on this one.

    The one on the right is a paper control strip, and again it's (supposed to be) checked with a densitometer although he said that some labs just eyeball-check it. The "stain" square is supposed to be totally white and the D-max totally black, with LD and HD being certain shades of grey with no color cast. I'm not really sure about the Y-max, but it appears to be a solid yellow. (Anybody know? Class?)

    I thought that the gang here would find this of interest. I did.
    Attached Thumbnails Attached Thumbnails fujiqa1.jpg   fujiqa2.jpg  

  2. #2
    Robert Brummitt's Avatar
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    When I was a "Lat Rat" I had to run test strips offen. Before, during and after runs.
    "We are what we repeatedly do. Excellence, then, is not an act but a habit"
    Aristotle

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    Running control strips is essential to keeping any lab producing quality work. Any lab that will show you their control strip log is one you should be able to trust. You can't be a Kodak Q-Lab unless you run control strips, I think you even have to upload the results to Kodak.

    Your FOAF better be careful, some Wal*Mart bean counter's going to crush him for wasting money on control strips.

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    The measure of the dmax blue density minus the yellow patch blue density gives a check on bleach activity. The high density minus the low density is a measure of contrast and balance. Individual control strips are only part of the story the rest is the control plots which are graphs of the measured parameters or more correctly how much difference there is between the reading at hand and the standard. The graphs were frequently reffered to as clothslines after their resemblance to the back yard drying apparatus.

    In quality control one hopes for smooth but not strait lines. When the plots move beyond limits they are the first step in figuring out the corrections. The other shoe of running a good process is keeping "in spec" that is maintaining temp and specific gravity and other parameters because if a compensation is made to correct a control problem one has not solved the problem and it invariably comes back to bite. Especially in c-41 where many different products are processed in the same soup.

  5. #5
    wogster's Avatar
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    Quote Originally Posted by John Shriver View Post
    Running control strips is essential to keeping any lab producing quality work. Any lab that will show you their control strip log is one you should be able to trust. You can't be a Kodak Q-Lab unless you run control strips, I think you even have to upload the results to Kodak.

    Your FOAF better be careful, some Wal*Mart bean counter's going to crush him for wasting money on control strips.
    It really comes down to a couple of things, "waste" money on control strips, or "waste" even more on trying to fix the problem of poor quality work. In the days when 99% of the processing was for your typical consumer where quality was determined by being able to tell the difference between Uncle Joe (with a full beard) and Aunt Martha (just a moustache ) then you could get away with being a little off. Now that the typical consumer has a digital camera now, and more and more of the film users are hobby photographers. Running a poor quality lab is going to mean a lot of your customers are not going to accept the results, so that means refunds and repeat work. Refunding $100 in prints because the chemistries are off is a lot more expensive then a $1 control strip.
    Paul Schmidt
    See my Blog at http://clickandspin.blogspot.com

    The greatest advance in photography in the last 100 years is not digital, it's odourless stop bath....

  6. #6
    benjiboy's Avatar
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    If this is the case , why is the output of so many minilabs so poor ?
    Ben

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    Frankly I've rarely had a processing issue with the local mini-labs - instead, it was always a dust & crap & scratch issue. And seeing how they treat the processed negatives at many mini-labs I've observed (as though they are made of titanium and almost nuke-proof, instead of something that should be treated gingerly and with respect), its no surprise. They teach the machine jockeys to push the right buttons but don't teach them about how to properly care for the film.

    Sadly, these labs seemed to start up well, then went downhill with time. A minilab in my local Safeway grocery store (the lab was closed a few years back) and more recently the lab in a new Walgreen's followed the same pattern - when they first opened the people all sported some sort of patch or badge stating they'd been trained & certified by Kodak or whomever. You talked to the people and they really knew their stuff, and the results were superb - easily good enough for anyone and about as good as I got from my local custom lab that hadnled my wedding business. Over time, though, the original experts would be forced to train others in the store to do processing because the cheap stores wouldn't send them to the training. Eventually the original experts would leave, and the training was passed from body to body, getting worse all the time, until the results were almost never acceptable. I would suspect this guy at Wallyworld will see the same thing happen - he'll be given warm bodies and told to train them, and it'll all go downhill.

    The hard part for me is the only place to get consistent good quality anymore seems to be the pro lab, and really, I can't afford to be sending every single personal roll of film there at the prices they charge. I guess I may have to resort to trying out the mailorder labs (and boy I sure remember the crap quality I got from them in return for their low prices) or develop my own C-41 films.


    Jim

  8. #8
    wogster's Avatar
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    Quote Originally Posted by benjiboy View Post
    If this is the case , why is the output of so many minilabs so poor ?
    Because people don't complain.... Most minilabs were set up during the times when 99% of the rolls they saw were crap before the lab got a hold of them. They key ideal was to get as many rolls through the soup as possible and print them even quicker, the machine operator put the thing on full auto and never checked the output. Many people thought the problem was their cheap or worse disposable camera,* We know that the lighting is good, the composition is good, the camera is good, our film is fresh and of a good quality, so the fact that our $5000/hr model is a lovely shade of green probably isn't us, it's the crappy lab. The lab at the camera store is likely to be better monitored the the lab at wally world.

    I once used a grocery store mini-lab, the roll came back with a huge scratch from leader to spool, I went back, asked to speak to the manager, and nicely pointed to how his machine ruined my pix. He offered a replacement roll and a coupon for free processing. I took the roll and politely told him where to put the coupon. It soon became a moot point anyway because Agfa who had supplied the machine, sank, probably more telling though, the equipment was not replaced. I switched to using a pro-lab which cost more, but they always provided excellent results, even though they also used a mini-lab (Fuji Frontier) negatives always came back spotless and the prints were also excellent. I went back to my B&W roots shortly there after and processed my own film again. Used a hybrid setup for a while, until I went d*****l, to tell how well that went, I am back to film for B&W again. Even debating about trying large format, of course that leaves friends and family who are worshipping the megapixel slightly
    Paul Schmidt
    See my Blog at http://clickandspin.blogspot.com

    The greatest advance in photography in the last 100 years is not digital, it's odourless stop bath....

  9. #9
    msage's Avatar
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    Quote Originally Posted by benjiboy View Post
    If this is the case , why is the output of so many minilabs so poor ?
    Ben
    The quality is poor because it takes more than running control strips and printer tests. It is only the first step. Unfortunately, many labs don't do that.
    The quality comes from having trained, committed and dedicated employees. It helps a lot if they love photography. I feel that we (photographers) get the quality we deserve (as a group or whole). We are looking for the cheapest film, cheapest processing and cheapest printing. It is so hard to make a living as a printer or lab tech.
    Michael

  10. #10

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    dmr, regarding your question on Y-max, I'm going to try to exceed the limit of your curiosity.

    As analogsnob pointed out, it is a check on the bleach, where one measures the difference between the "black" patch and the yellow patch. Why? Well, the black patch has all 3 color layers heavily exposed, to make a maximum amount of cyan, magenta, and yellow dye, right? Ohterwise it wouldn't look black. So this puts the maximum strain on the bleach - maximum amounts of silver in all 3 layers have to be bleached out. So the first sign of a bleach problem should show up here.

    You might think this black patch is all you need, but wait! What if the developer activity changes? Exactly! The black patch density will go up and down with developer variations. So how do you tell which one is causing the change? Now the reason for yellow patch becomes apparent. Whatever the activity of the developer, density of the yellow dye in both the black and the yellow patches will track closely together. However, when bleach begins to weaken, the first signs of failure will be seen in black. So by always comparing the two patches to each other, you have a very sensitive test for just the bleach.

    Today, most places probably use a computer program to check the control strip plots, so it's not necessary to understand the guts of the process. The computer will advise on any possible problems, at least within the realm of what it can "see". I have to say that I'm a bit amused that you find it interesting; that is something of a rarity today.

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