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The Original is Not Always Right – Lab Prints

Printing an image can introduce a range of issues that may adversely affect the result. In the case of a traditional RA-4 print, the chemistry needs to be within specifications. A good lab will run a variety of tests, on a regular basis, to check the condition of the processing solutions.

One such test involves running a control strip: a piece of photographic paper pre-exposed with a series of color patches (black, grey, white, cyan, magenta and yellow). Once processed the test strip is passed through a densitometer that reads the color density for each of the patches. The information is then plotted onto a horizontal graph with pre-determined action and control lines, both above and below the centre of the graph. Over time the operator keeps an eye on the results and takes preventative action to ensure that, while the process may move up and down from day to day, it doesn’t move too far from the centre of the graph. Once the process crosses the line into the action limits then action can be taken to bring the process back into line before the problem becomes visible. Such action can be taken without the need to halt the process. If the out of specification graph is not acted on quickly enough, then the problem is likely to get worse and become visible in actual photographs. Once this stage is reached the graph would have moved beyond both the action and control limits. The process is then deemed to be out of control and the lab should stop putting work through until the process is brought back into specification.

A relatively common problem is caused by under active developer. It might be under concentrated (e.g. too dilute), too low in temperature, under agitated, insufficient in amount, or not in contact with the paper for long enough (e.g. the machine may be transporting the paper through too quickly). Once the developer becomes under active, to the extent that it causes the process to plot beyond the control limits, blacks in the print would display a bluish color caste. Enthusiasts who’ve undertaken color printing from home would quite possibly have experienced the phenomena, without necessarily knowing the cause or remedy.

It’s also important to consider the palette from which the original image was made. In the case of print film, we need to consider the following:

  • The condition of both the film (C-41) and print (RA-4) processing chemicals
  • The accuracy with which the printer has been set up to correctly print images from the specific combination of film (eg. Kodak Gold 100) and paper (eg. Fuji Crystal Archive) in question
  • The quality (time, temperature, concentration, agitation, aeration and cleanliness) of the chemical processes
  • Modern labs incorporate printers with scanners and digital light sources to expose the paper. In the process of scanning the negative it is digitised. So, with the possible exception of some very poor and/or incredibly isolated regions where the owner still runs an old technology print processor, all images printed in a conventional 1-hour lab are digital, whether the image originated from a film or digital camera. And of course the act of scanning a piece of film could also, conceivably, alter the color and/or tonal rendering of the original image.


© Copyright All Rights Reserved

Glenn Guy, Blue Sky Photography


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