The Darkroom
Using The Ilford EM-10 Density Meter

I love gadgets. In fact, if it has blinking lights, beeping noises or a flashing LCD display, I usually can't live without it. Years ago when I was working with a dichroic enlarger I discovered the joys of the EM-10, and I haven't been without one since. If you use a continuous-light enlarger, then you need one, too.

The EM-10 uses a single 9v battery that seems to last forever. At least, I can't remember the last time I put in a new one. Like all good gadgets, this one has LEDs--two red and one green. The lights allow you to know exactly when you have the correct density. You simply place the EM-10 on your easel, and position its sensor in the correct area of the projected image. Then, slowly rotate the f/stop ring of your enlarger lens until the red LEDs go out and the green one comes on. At that point, you have the exact density needed to make the print.

You can program this meter to deliver the correct density for almost any tone value that commonly reoccurs in your prints. Simply make a good print by trial and error. Then, place the sensor in an area that you want to program. For example, you might want to create one for a flesh tone, or 18 percent gray, or a white highlight, or maybe D-MAX (maximum black).

When I print with a dichroic enlarger, I always try to use an exposure time of 10 sec. That long of an exposure is necessary to deal with the quartz-halogen bulb's filament as it warms up to its full brightness and as it cools down to its off setting. In color work, pre-glow and afterglow can cause endless color balance problems if you use too short of an exposure time.

I use my EM-10 for black and white as well as color printing. The program numbers (shown right) that I've written on the bottom of it are for use with Kodak's PolyMax paper. They are the settings used for each particular tone value that I want to measure. Just place the dial at the "program number"; place the sensor in the correct area of the projected image and slowly rotate the f/stop ring until the green light comes on. How could anything be easier? It saves tons of trial and error testing.

If you are going to use the EM-10 with color paper, then you have to remember to always use it in relatively light areas of the projected image. It was designed for black and white printing, and as such it has a limited range of sensitivity. The orange mask in color negative films greatly reduce the brightness of the projected image, thus reducing the effective range of the meter. Still, if you simply remember to always take readings in light areas (as opposed to dark areas) of the projected image, the EM-10 is extremely useful in color printing with a dichroic enlarger.

Not only can you use the meter to zero in on the correct density setting for an unknown negative, you can also use it to allow you to change magnifications and still produce prints that exactly match in density. Just make your first print and then use those settings to program the EM-10. Then, set up the magnification you want for the next print (from that same negative) and place the sensor back in the same area where you programmed it; slowly turn the f/stop ring until the green light comes on, and you will have a perfect density match for your first print.
In order to program the EM-10 (with black and white or color negative film), first you have to make a good print by trial and error. Then, place the sensor in an area of the image that you want to program. Next, with the enlarger's f/stop ring set to where you had previously made the good print, start slowly turning the meter's control knob until the green light comes on. At that point, you have created a program. Make a note of the number that the dial is pointing to. That number is the "program." After that anytime the dial is set to that number the exposure time is the same (as what you used to create the trial and error print); and you are using the same emulsion batch of paper and developer--you will be able to reproduce the exact, density--regardless of the magnification--by adjusting the f/stop ring until the EM-10's green light comes on again. Remember that the paper speed can vary a little from one emulsion batch to the next, and the brand, working strength, freshness, temperature, processing time and agitation of the paper developer all have an impact on print density.

You might be wondering about my setting for D-MAX. When you expose film on a camera, there is a proper exposure for a given speed of film. If you provide more or less exposure, you might or might not get an acceptable image. This is also true for photographic paper. There is always a theoretically correct exposure for any given photographic paper. If you provide more exposure, you are simply overexposing the paper. You may or may not get an acceptable picture. The theoretically correct exposure level for any given photographic paper and negative combination can easily be determined. Simply make a series of test exposures until the edge of the film (where it is mostly clear, it's called D-MIN plus base fog) produces just barely solid black in the print. At that point any additional exposure is "overexposure" since you can't produce a darker black. That point--this shade of black--is called D-MAX (Density Maximum). Yes, more exposure might bring up detail in the highlights that would otherwise be washed out in the print, but it will also obscure detail in the shadows as they get darker. However, if the film requires more exposure to bring up those highlight details, then, by definition, the film has been overexposed on the camera.

The EM-10 can be programmed for D-MAX. After that, just place the sensor in the area of the edge of the film; set the dial to the correct (D-MAX) program number, and adjust the f/stop until the green light comes on. You will then have an exposure for the paper that is theoretically correct. Obviously, you may have to further adjust it to deal with any over or under camera exposure on the film that might exist in the image that you are working with. But, at least you'll know how close to correct the camera exposure was.

As a rule of thumb, I tend to overexpose on the camera all of my color negative work. Most color negative film will tolerate about four f/stops of overexposure before it starts to cause a loss of shadow and highlight detail in the finished print. Most black and white film is a little more sensitive and needs to be exposed more accurately if you are going to get the best that it has to offer. And, of course, slide film is the most sensitive of all. It needs to be exposed almost perfectly if you are to get good slides. Speaking of slides, the EM-10 works just as well when printing slides as when printing negatives.

Oh, I almost forgot. Not only is this a great gadget that you shouldn't be without--it's easily affordable. You can expect to pay less than $30 for the EM-10 from most mail-order sources.

If you'd like more help with your wet darkroom, or your digital darkroom printing, you can write to me with specific questions care of Shutterbug, or send e-mail to: