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[CanterMike@xxxxxxx]

In an ongoing discussion, Bob Maxey contributes:

<< 
 
 >>What is the difference? In many cases the equipment is the same. Chances
 >>are the pro labs print your negs just as lousy as any 1 hour
 >>lab........but they slow down the volume of work, charge more money, and
 >>allow time for the inevitable " redo's" until they achieve the higher
 >>quality standard.
 
 One-hour labs do not generally use enlargers, so traditional corrections like
 dodging and burning are not possible. If a one-hour lab were given the time,
 yes... they might be able to do a better job. However, then the lab becomes a
 custom lab. The bottom line for most is cost. My experience in the business
 shows that professional oriented labs generally do a better job than a fast 
lab.
 But I will also concede that both types of finishers have had problems.
 
 RM
 
  >>

While Bob points out one attribute, it may surprise some of you to know that 
a considerable amount of a "custom" lab's work is done on automated 
equipment.  Prints that are really "made by hand" tend to be remarkably 
expensive, and considered to be a premium service.  The automated machines 
used in custom labs are usually better maintained and calibrated by people 
who (usually) actually do care (or may be paid enough to fake it better).  No 
lab can afford to "re-do" prints endlessly: the custom lab takes care to get 
it right the first time.  (Wasn't it here that I read "if you don't have the 
time to do it right, when will you have the time to do it over?)  When was 
the last time you saw a VCNA used in a minilab?

To me, the most important difference in labs is in the film processing, not 
the printing, and can be summarised in one phrase: "dip & dunk".  When we 
process film at home, we usually wind the film on to reels, seal them in 
tanks, and pour the chemicals in and out through a light proof funnel built 
in to the top.  Human error(s) in temperature, timing & agitation can lead to 
inconsistencies from batch to batch, plus this process is too labour 
intensive for the dozens, even hundreds, of rolls per day that a business 
needs to turn a profit.  There are three common types of automated/mechanised 
processors in use today: rotary tube, roller transport, and dip & dunk.  

Rotary tube processors (like Jobo, PhotoTherm & Wing-Lynch) can vary from 
mostly manual to fully automated units.  The film is loaded onto a spiral 
reel and sealed into a tube, similar to a small tank.  The tube (or drum) is 
then placed into a machine that revolves it in a controlled manner, and 
usually provides a tempering bath for consistent temperature.  The fancier 
units will even pump the chemistry into the tube, time it, and drain it back 
out.  Like a home lab, the chemical usage is referred to as "one shot" (used 
& discarded).  Many commercial photographers use these, and some custom labs 
use them for low volume (special and therefore expensive) processes.

I know that many of us have extensive lab experience, usually retail 
minilabs.  The dominant type of film processor used in these businesses is of 
the "roller transport" type. In a roller transport processor, the film 
travels up & down racks that are submerged in the chemistry.  The length of 
the rack(s) & the motor speed determine how long each linear inch of film is 
immersed in each step.  As the film reaches the top & bottom of the racks it 
must be guided though an arc to the next section.  Racks must be kept clean 
to avoid scratches & damage to the film.  RT processors offer a more 
economical chemical usage, too.  Rather than constantly dumping & remixing, 
exhausted chemicals are "replenished" by adding a few milliliters of fresh 
chemistry for every (X) number of square feet of processed film.  RT 
processors were originally engineered for the motion picture industry (have 
you ever tried to load a couple hundred feet of film onto a reel?), and were 
adapted into common usage by the economies of scale required by wholesale 
labs (Kodak et al.) where dozens of rolls are spliced together into one 
really long roll (400' is not uncommon) before processing.  (So when Kodak 
screws up, take some small comfort in the knowledge that they probably 
screwed up 50 other rolls, too....)  (Of course, that could represent just 
another long weekend for George....)

Combining these techniques leads us to the dip & dunk processor.  It offers 
the businessman a high through-put,  precise timing and temperature control, 
and replenishable chemicals, but best of all (and what is important to us), 
the film never touches a roller, guide, or crossover.  Roll film is wound 
onto a spiral reel, just like at home, and then many of these reels are hung 
on a rack (hanger) which is dipped into the chemical tank, timed, then lifted 
out and transported to the next bath, where it is dunked, timed, etc..  The 
steps repeat throughout the rest of the process.  Agitation is usually 
provided by a burst of nitrogen gas.  These machines can break down (just as 
any machine can) but the labs that invest in these are usually of a high 
enough calibre to properly maintain them, making the MTBF pretty long.


So here's a test: 

Take a brand new roll of film.  

Wind the leader in so it looks like its been exposed (roll film users have to 
work harder here).  

Tell the clerk that it is a blank roll as a scratch test and please take good 
care of it.  (This is important as many labs take blank rolls and wad them up 
terribly, assuming you screwed up.)  

DO NOT tell them that you are testing THEM!  I hate to encourage anybody to 
actually lie, but let them assume you are checking out your camera for 
scratches....  

See what you get back.


Sorry to be so long-winded.  I'll step off my soupbox now.

Mike Canter