Frances Schultz article

from 'Darkroom User' magazine, 1997

Colorstar 3000

part 1 - In at the deep end!
part 2 - Chromogenics
part 3 - Reversal Role


You decide you want to learn colour printing. You go out and buy everything: a colour head for your enlarger, a colour analyser, a colour processor -- the lot. This seems like the logical approach. The technology is there, so why not take advantage of it? Then someone tells you that you shouldn't even try to use a colour analyser until you know all about colour printing... The Colorstar 3000 colour analyser with probe

I wasn't sure they were right. In fact, I thought that if you worked methodically, and if you already understand black and white printing, you should be able to use a colour analyser to teach yourself colour printing. After all, a colour analyser gives you that much more information to go on. After about a week of testing I came to the conclusion that if you proceed systematically and make careful notes, the colour analyser can indeed help you to learn colour printing very quickly -- but you do need to write everything down, or you will soon lose track of where you are.

Equipment

     The enlarger was no problem: I already had a Meopta Magnifax with a dichroic colour head. Likewise, I could use my existing Nova Tank for processing. Paterson provided Photocolor Printmaster RA chemistry and I bought some Fujicolor Super FA5 paper. The original Colorstar 3000 I used was an eight channel unit, loaned by Nova Darkroom Products. Later I got a new 100 channel unit from Lici Colorstar. Rather than just reviewing the product, I wanted to see if my theory was correct.
     I ended up writing three articles about my experience with the Colorstar, one about printing colour negatives, one about printing transparency and one about printing black and white materials. The Colorstar not only taught me how to print from the colour materials as I had hoped it would; it taught me a lot about black and white printing too. But more about that later. First of all, let's look at printing colour negatives. Before you start you have to make some decisions about the hardware and the chemistry you are going to use. If you have not printed colour before, it comes as a bit of a surprise to learn that dichroic colour heads are not all the same. Mine has the usual filtration (cyan, magenta, yellow) and is scaled from 0 to 200. Others might go from 0 to 150 or 0 to 250. The filtration units are essentially arbitrary, and although there are 'families' of filters, the results from one enlarger are rarely transferable straight to another even inside one 'family'.
     This means that no two enlargers will require the same adjustments to get the same results, so you have to rely on your analyser and your own judgement to get the best results with your enlarger. Once you understand this, you need to choose your chemistry and your method of working. At the bare minimum, RA-4 uses two baths: developer and bleach fix. This is all you need, but because I was using a Nova tank, I also used a brief water wash - - no more than a dip with brief agitation -- between the two. The best current advice from Paterson is to use a water rinse rather than a stop bath, but other chemistry manufacturers may have other recommendations. Nova tanks allow temperature control to plus or minus one quarter of a degree Celsius (half a degree Fahrenheit), so I didn't have to worry about temperature variation. If you don't have any way of controlling temperature accurately, consider using Paterson Ambient RA-4 chemistry. My tests have given me excellent results at temperatures ranging from 20 to 40 degrees Celsius.
     The most important difference between colour printing and monochrome is that as well as getting the right exposure, you also have to get a pleasing colour balance. I say 'pleasing' because this is not necessarily the same as the most accurate colour balance. Some people prefer a warm cast to their prints, while others may find a cooler, bluer cast more pleasing. Of course, they will all tell you that their prints are neutral.
     You could, with practice and careful observation, manage to learn about colour theory just by experimenting with the Colorstar, because the 'Color Star' itself is a graphic display which guides you to the right colour balance. If you kept careful notes about filtration changes and how they affected the colour, you could work out the theory from first principles -- eventually. But you will get much further, much faster and with far less frustration, if you do some reading about colour theory and colour printing first. You will also understand the instruction book better.

Some homework

     First of all, I read everything I had access to: old magazine articles, books, the relevant Focal Encyclopedia Aentries, and a correspondence course handbook I had been sent for review, The ColorBat Lab Pro Handbook by Darryl Nicholas (a colleague who writes for Shutterbug in the U.S.)
     Colour theory for photography may not be quite as you remember it from school unless you had a teacher who was interested in photography. The additive primary colours are red, green and blue (RGB). Their complementary colours are cyan, magenta and yellow (CMY, the subtractive primaries). The three subtractive primaries are normally used in photographic enlarging; by changing their proportions, we can get to the right colour balance.
     As any black and white printer knows, MORE light through the negative makes a DARKER print. Without really realizing about it, we learn to think backwards. The problem with colour negative printing is that you have to do the same for colours. Colour negative film is almost impossible to judge without printing, because real world colours register as their complementary colours on the film. An overall orange mask is normally incorporated to improve the spectral response.
     There are three dye-forming image layers in the paper, corresponding to the three subtractive primaries. Each of these layers responds to different colour light. The green sensitive layer forms magenta dye, the red sensitive layer forms cyan dye, and the blue sensitive layer forms yellow dye.
     Just as we automatically think 'backwards' in conventional monochrome printing, so that more light makes a darker image, so do we have to think backwards in colour printing. If you have a cast of a particular colour, you need to add more of that colour in order to remove the cast. For example, if your print is too magenta, you add magenta filtration. This is easy enough to remember. After all, a print that is too light requires more light, not less.

(1) This picture was taken in the late afternoon when the light was very warm and golden. This is the rendition the Colorstar gave me. I like it, but my negative was not perfectly exposed and the sky did not have enough colour, so I decided to 'play' with it using the Colorstar's recommendation as a base. This first picture had a rather 'lemony' quality to the light. It reminded me of old Kodachromes from the 1950s.
(2) For my first 'interpretation' I left the colour balance alone, but wanted more density, so I added a quarter stop and burned in the sky. I think I overdid it. I have seen sunsets that look like this, but the other renditions are more natural.

(3) The density in my second print seemed a little too heavy, and I wanted to experiment with colour balance, so for this exposure I increased both magenta and yellow filtration -- the magenta by one unit and the yellow by four. My goal was to cut some of the red light and add some blue to see if I could get some colour into the sky, but that made the foreground look unnatural. The added filters did not change the density quite enough.

(4) I went back to my original exposure time, but removed three units of yellow filtration to take some of the blue out of the foreground and the house. Then I added a lot of yellow filtration -- 19 units -- and burned the sky. I like the mood: it looks like a very cold winter afternoon. As I remember, it wasn't that cold out, but that's part of the fun of colour printing. You can change your colour balance to suit your mood.
if you push you will get a window with the above images in an image changer
Subtractive Printing

     The most common method of printing colour negatives is the white light or subtractive method. You start out with white light, and you then filter out (subtract) the colours you don't want. In the rarer additive method, you start out with three different coloured lights (usually red, green and blue) and add them together in different proportions.
     Filters transmit their own colour and either absorb or (in the case of dichroic filters) reflect their complementary colour. As is the case with any filter, the less filtration you have, the more light will be transmitted, so exposure is altered as you alter filtration. An analyser is worth having in order to make this correction easier, even if you do not see any other use for it -- and it does a great deal more than this. It doesn't mean that you can always get the results you want without any knowledge of colour theory, but (if you have the analyser programmed right) you will generally get a good work print in one go, without having to do 'ring-around' prints. Once you have a good work print, then you can decide if you need to dodge or burn an area, to tweak the colour balance to give a warmer or cooler look, or even to add some yellow filtration to burn in a white sky.


Red, yellow, green, blue -- what a test. I took semi-integrated readings off the foreground, the brick wall, and the breeze block wall. I wish the sky had been bluer, but there was a very high, thin cloud layer. The Colorstar gave me a good print first time.
Programming

     The first challenge therefore lies in programming the analyser. A good place to start is by reading the instruction book and experimenting with the unit as you read so you can relate the instructions to it. This will give you a general idea of what the keys do, and get you used to 'talking to' the Colorstar.
     If you already know how to print colour negatives, you can use a negative you have printed before to autoprogram your analyser, as long as you know the enlarger filter settings and exposure time. Otherwise, the instruction book tells you how to program a channel for neutral grey, and that's where you start. The great attraction of this is that it doesn't require an 'ideal' or 'perfect' negative, with a good mixture of colours. A straight picture of an 18 per cent grey card is all you need -- and the Colorstar comes with just such a negative. Once you have a channel set for neutral grey, then you can use that information to help you program other channels. I will explain this later.

The analyser

     At this point we need to take a guided tour of the analyser. It is a small black box with six function keys, fifteen LEDs, and an alphanumeric display screen.
     The unique feature is a three-pointed star below the alphanumeric display: this is the Color Star which gives the unit its name. It is made up of twelve LED lights, arranged in three arms or points of four LEDs each. One is yellow; the second is red; and the third is green. These light up and go off in response to your enlarger's filtration, as you will see later on.
     To the left of the star are three more LEDs, arranged vertically. These tell you what the information on the alphanumeric display relates to: the categories are Y (yellow), M (magenta), D (density -- signified by an orange light). Then there are the six keys.
     'LAMP' turns the enlarger on and off for focusing and measurements.
     'EXPOSE' times your exposures.
     'ANALYSE' allows you to measure the light falling on the baseboard with the probe (see below) or to use the probe to measure the log density of each colour as well as the overall density.
     'STAR'(*) selects one of the three LEDs on the left: Y, M, D as described above. It can also be used to make adjustments to a single channel or to all of the channels at once.
     'Arrow' keys (one pointing UP, one pointing DOWN) are used to select channels, for changing numerical values, and (when pressed simultaneously) for recording a new program in a particular channel. For now, select the channel you want by using these keys. I will come back to some of their other functions later, though still more are covered in the instruction book.
     A measuring probe plugs into the back of the unit. There are a number of different probe covers for different measuring methods. The clear cover is for spot measuring; this is the one you will use first. The regular spot probe is 6mm, but there is a stop you can insert to reduce the measurement area to 4mm. In addition to the clear cover, there is a translucent cover for semi-integrated and integrated readings and there is a square of diffusion material for fully integrated readings.
     There are also accessories for measuring black and white, which I will cover later on. In the same envelope as the stops and probe covers are three strips of 35mm film. These are colour negative, black and white negative and transparency strips of an 18% neutral grey card. You use these to establish your neutral grey channels.

I set my skin tone program up using this portrait of my favorite model, Ms. Holly Lewis. From my original Channel 3 program it took me five test strips to get what I wanted. Then I used the autoprogam to reprogram channel three from this print.
The next portrait is of me and Yeti. Channel 3 gave me an acceptable skin tone straight off, but finding a fairly accurate white for the cat was interesting in the extreme. It is quite likely that the trade processing was at fault and the negative had crossed colour curves. I did seven different test strips and got seven different colours of cat.
Installation

     Installing the Colorstar is very simple. Plug your enlarger and the probe into the back of the unit, and plug the Colorstar power cord into the wall. That's all. You are plumbed in and ready to go.
     Turn the unit on with the rocker switch at the back. Press STAR (*) and hold it down. Then press the EXPOSE key before releasing STAR (*). This will give you a temperature reading in degrees Celsius, which should agree with an ordinary thermometer within a degree or two. If it doesn't, there is something wrong. Either the probe is set up wrong, or it is defective. A trouble shooting section in the back of the instruction book will guide you on what action to take, but this is an unusual situation. Generally the temperature agrees, so you just press LAMP to return to the exposure time display.
     Next you need to tell the analyser what type of paper you are using: colour print paper, colour reversal paper, or black and white. If you have the newer 100 channel model simply select your channel, in this case channel 1. You do this by pressing STAR (*). The display should read either 'c.01' if you have a 100 channel unit or 'ch.1' if you have the eight channel unit. (channel 1). If it shows another channel, for example, 'c.02' or 'ch.2', then use the arrow keys to scroll through the numbers and set it to channel 1. I shall come back to the other channels later. If the display shows 'n.00', then the analyser is already set for colour print paper ('p.00' indicates reversal paper and 'b.00' indicates black and white). If it shows one of the other choices, change it to n.00. The DOWN arrow controls the letter and the UP arrow controls the numbers; the latter allows compensation for the paper's reciprocity characteristics, as described in the instruction book, but to start with keep it at '00'. Press LAMP to record any changes and to return to the timer display.
     If you have the older eight channel model, then switch the analyser off at the back. With STAR (*) held down, turn the analyser on. (Never press STAR (*) as you turn the analyser off; this can interfere with its memory.) Use the UP/DOWN arrow keys to set the paper type. As with the 100 channel model, the DOWN arrow controls the letter and the UP arrow controls the number.

Presetting

     The next step is to preset the colour values on the Colorstar to the suggested values given in the technical data of the instruction book. Select channel 1 (c.01 or ch.1).
     Now press STAR (*) again to show the set value for yellow. The recommended starting point is 600. If the reading is different then use the arrows to adjust it. Then press STAR (*) again to show the value for magenta. Adjust to the recommended starting value of 550. Press STAR (*) once more to get the overall density value. Adjust to the recommended starting value of 520.
     Press STAR (*) yet again to display paper type, and then three more times to display (in turn) the master Y-M-D values. The reading for each (on the alphanumeric display) should be A50. If it is not, then adjust each one using the arrow keys. If you make a mistake, just carry on pressing STAR (*) until you get back to the point you need to correct. When you have all the values set, press LAMP to record the changes.

Test print

     Assuming you have your chemistry mixed and at the right temperature, you are now ready to start printing with the analyser to guide you. Load the grey colour negative into your negative carrier and project to your paper size. As already described, the first goal is to set up Channel 1 for neutral grey. This is the key to everything else, and once you have worked through creating your neutral grey you will understand the machine a whole lot better.
     Turn off the room lights, including your safelight. As long as the analyser is switched on, the keys are visible in the dark. Indirect, very dim, yellow safelighting may not influence the Colorstar, but be sure to test it first by analysing with and without the light. If there are differences in either the exposure time or the lights which are lit on the Color Star, then leave the safelight off.
     Place the probe (with the clear spot cover) directly under the enlarger lens. Turn on the enlarger by pressing the LAMP key on the Colorstar. All filters should be set to zero. Press ANALYSE. Null the Color Star (make all the LEDs go out) by adjusting your enlarger filters.
     Only two arms of the Color Star will light up at any one Atime, usually yellow and red, so you need only to increase the yellow and magenta filtration on your enlarger until all the lights go out. If the green arm (representing cyan) lights up, reduce the yellow and/or magenta filtration until it goes off again. You never need all three filters at once. Occasionally the first light in one of the arms will blink on and off. Don't worry about it; you're close enough.
     Adjust the aperture on the lens to give an exposure time of 5.0 seconds. Press LAMP and remove the probe. Always press LAMP before taking the probe away. Now you can expose your first test strip; a piece of paper 25 x 125mm, 1 x 5 inches, is all you need. Cover half of it for a white reference: this is essential for getting your log density readings, as you will see shortly.
     Process the test strip exactly as you would a final print. Wash it thoroughly and dry it (use a hair dryer for speed). The colour of a wet print is dramatically different from that of a dry print.
     Compare the dry test strip with a neutral grey, preferably a grey card. The very first test strip I printed was a lovely shade of dark blue grey! This is where the note taking comes in.

Making notes

     At the back of the instruction book there are two sample log sheets. The first one is entitled "Setting-up your Colorstar 3000." Photocopy this, and use it to record the temperature readings; the paper used; the initial values for Channel 1; and the log density readings (which is the next step) for your first test strip. In order to learn more about the relationship of your enlarger's filtration system to your results, I would suggest recording your enlarger settings as well. If you can't fit them on, then design your own log sheets or make a reduced photocopy leaving a margin on the right.
     Insert the test strip under the probe cover (this is why it needs to be 25mm wide) so that the white part of the strip covers the cell in the probe. Remove the negative from the carrier; remove all filtration; and open the lens to maximum aperture. Turn off the room lights, including the safelight. If you neglect any on these steps you will not get a neutral grey.
     Press and hold down STAR (*), then press ANALYSE to set the densitometer mode. Release STAR (*) and press ANALYSE a second time to zero the reading. Shift the test strip so that the grey area is covering the cell. The log density (D) is displayed on the screen (the orange LED next to D is lit). Enter this value on the log sheet. Press STAR (*) for the log density of Y (yellow). Another pressure will show the log density for M (magenta), and one more will show the log density for C (cyan, indicated by both Y and M LEDs lighting up simultaneously). If you want to retrieve or re- check any of the log densities just press STAR (*) until the reading you need is displayed. I keep a small torch handy so I can see to write these values down.
     Ideally, all of these readings should be within 0.02 of 0.55. If they are more than 0.01 or 0.02 different, use the analyser to help you to improve them automatically. Press STAR (*) yet again and when the display reads 'ch.r' press both arrow keys at the same time. This will reprogram the analyser to get closer to a neutral grey, i.e. closer to 0.55. Press the LAMP key to save the new values in the Colorstar.
     Read the new Y-M-D values for channel 1 in turn from the alphanumeric display and record them on your log sheet; they replace the original starting-point values, described above, of Y=3D600, M=3D550, D=3D520. Note that Y-M-D values are not the same as the log density values which you get from the test strip.
     Replace the negative, put the filters back into the light path. Turn on the enlarger, null the Color Star and adjust the lens aperture for a 5 second exposure. Make a new test strip. Dry it and analyse it, as described above. If the log density values are not within 0.01 or 0.02 of 0.55, then reprogram the analyser once more and record the new values. Repeat this process until you get a neutral grey that you are happy with and which registers log densities as near as possible to 0.55; variations of 0.01 or 0.02 are not likely to be significant. It took me five iterations to get a neutral grey.
     If you have recorded each step on your log sheet, together with your enlarger settings, you can see what changes you made to the enlarger filtration to get to the neutral grey.
     Once you have a good neutral grey, the next step is to program some other channels using the values obtained for Channel 1. Press STAR (*) to get the 'c.01' reading. Use the arrow key to change to Channel 2 (c.02 or ch.2). The instruction book suggests calibrating Channel 2 for a warm tone by inserting almost the same values as Channel 1 but subtracting 6 points of yellow and 3 points of magenta. Press STAR (*) again to get Y (yellow) and change the value with the arrow key. Press STAR (*) to get M (magenta) and change the value with the arrow key. Press LAMP and you have now programmed Channel 2. If you print a test strip you will see just how little you have to change your filtration to null the Color Star.
     Lici recommend that channel 3 can be programmed for a skin tone. Begin by subtracting 12 points each from yellow and magenta and adding 9 points to the density; again, use the arrow keys to change Y, M and D values.
     This is however no more than a starting point. No two people have exactly the same skin tone, and sometimes you may want to enhance skin tones anyway. If you do a lot of portraits you will probably want several different skin tone channels.
     Begin with as 'typical' a skin tone as you can find. Meter from whatever you consider the best point; make a note of where you took your reading (on a reference print if possible). Make a test strip. If (for example) the result is too magenta, then add 2 points of magenta to your filtration and run another test strip. When you have a skin tone you like, you can change the Channel 3 program very simply. Turn on the lamp and place the probe on exactly the same area that you metered before. Press ANALYSE. Then press STAR (*) and, while holding it down, press the two arrow keys at the same time. Next, use the arrow keys to set the correct exposure time. Press LAMP to store the program and then remove the probe. It took me half a dozen test strips to get a skin tone that I liked.
     The instruction book recommends setting up Channel 4 for neutral semi-integrated readings. Begin as you did when setting up Channel 1. Use the same grey negative; analyse, using the clear spot cover; null the Color Star; adjust the aperture; and press LAMP to end.
     Now remove the spot cover from the probe. Replace it with the diffuser cover. Place the probe under the enlarger lens. Select Channel 4 and press the ANALYSE key. Hold STAR (*) down and press both arrow keys at the same time. Adjust the exposure time using the arrow keys to make the display read 5.0. Finally press LAMP and remove the probe.
     You can then use Channel 5 to set up a warm tone version of your semi-integrated program by making the same adjustments to between Channel 4 and 5 as you did between Channels 1 and 2. You now have five channels to choose from, and you can start printing for real.
     It is usually best to choose a negative which doesn't have any large areas of a single colour and to use Channel 4 or Channel 5, the semi-integrated channels, to make your initial exposure. Put the negative in the enlarger; focus and compose; and put the probe on the baseboard, with the diffuser cover in place. The filters must be out of the light path.
     Pick an area of the picture which has a mixture of colours, and which seems to be of average density. Put the probe over that area and press ANALYSE again. A beep will tell you that this reading has been stored. You can then read up to 7 more areas the same way and store each reading. Leave the probe over the area you read last. Dial in the enlarger filters to null the Color Star.
     Next, adjust the lens aperture to get an exposure time of 5 to 10 seconds. Shorter exposures may be 'hot' because of the warming and cooling of the lamp, and longer exposures may run you into problems with reciprocity failure. Press LAMP to store the reading. Remove the probe and press LAMP again to turn off the enlarger lamp.

Click the image to enlarge it
I made this diagram to help myself visualize what happens to the light when it is projected through a magenta dichroic filter. The magenta light is transmitted, while the green light is reflected.
Keeping a chart of what you need to do to remove colour casts next to your enlarger is a great help.
First print

     Now you can make your first print. Put the paper in the easel, and press EXPOSE. Process the print, wash it and dry it. It should be pretty good, and by now you should be much more confident about using the analyser. Certainly, you will understand a lot more about it. If you want, you can set up more channels. For instance, you can have one for green if you do a lot of landscapes, or as mentioned above, you might want to set up other skin tone channels. As already mentioned, the newest Colorstar has 100 channels.
     If you switch paper or chemistry, or work at a different temperature, or if your chemistry or paper has aged, then a neutral grey test (channel 1) should be adequate to determine what changes you need to make to get back to your original results. You can make the necessary changes to all the other colour negative channels simultaneously by using the 'Master Channel' option, as follows. On the first pressure of the STAR (*) key, the display screen will read 'ch.r', which is what you use to reprogram a single channel. On the second pressure, the display will read 'a.r', which reprograms all channels. Now press both arrow keys at the same time, and any adjustments which need to be made to each channel assigned to that paper type (in this case n.00) are made automatically.
     There is lots more you can do with the Colorstar, such as making fully integrated readings. Just follow the instruction book. If you use your log sheets to record your enlarger settings as well as the colour values and log densities, you will begin to see colour theory in action. Surprisingly quickly, you will find that you are turning out first class colour prints, reliably and easily.
     The pictures which accompany this article are snapshots, trade processed by my village mini-lab. Because I had never learned colour printing I have always used slide film or black and white film for professional pictures and negative film in a compact camera for 'happy snaps'. Now that I have the Colorstar and I know I can print colour film, I expect to start using colour negative film with my professional equipment, from 35mm to 4x5 inch.


From Darkroom User magazine. For subscription datails contact Ed Buziak (Publisher), Foto Format Publication, PO Box 4, MACHYNLLETH, Powys SY20 8WB, United Kingdom. Tel: 01654.703752 e-Mail: CompuServe 100410,1561