The timers you use in the darkroom are an important part of your darkroom equipment. You use a timer each time you develop a roll of film, make an exposure, and develop a print. Yet often not a lot of thought goes into selecting the timer or timers purchased. As a result, people often end up with timers that are not ideal because they have been purchased out of expediency, or because a particular timer was recommended by a friend or store clerk, or because they got used to a certain timer in another darkroom. When next shopping for a darkroom timer, use the following information to help select a timer with the combination of specifications and features that best meets your needs.

Applications

First consider how you will be using the timer. Ideally you would want one timer to be used with the enlarger to control the exposure, and another timer for process timing. An enlarging timer must control relatively short exposures, while a processing timer must be capable of much longer durations. General purpose timers can be used for both enlarging and processing, but may not be the ideal choice for either. Consider how much more convenient it is to have a dedicated timer specifically selected for each job.

Enlarging Timers - are designed specifically to control short exposures and usually will have a maximum setting of 60 or 99 seconds. Some of the inexpensive enlarging timers have increments of seconds only, but for precise exposures of less than 10 seconds an enlarging timer should also be capable of being set for 10ths of seconds as well. Since the times are short and any significant variations will affect the print, accuracy and repeatability (see "Specifications" below) are more important for enlarging timers than process timers.

Process Timers - The basic requirement of a processing timer is that it has the capability of timing in minutes and seconds. Therefore a wide variety of timers can be used for this purpose. Everything from the clockwork Kodak timer, the GraLab 300, battery powered LCD timers, and elaborate and expensive digital timers. The simplest timers will require the user to reset the timer for each step. The most sophisticated process timers are capable of being pre-programmed for the multiple steps in a particular process. Some are designed to accept memory modules with the various steps pre-programmed. All that is then required is to restart the timer for the next step. Although they differ greatly in appearance and the way they operate, both the Omega Program Timer and the CT-40 above are examples of programmable process timers. If there is an electrically powered device that must be started and stopped during processing, such as a processing drum agitator, it is advantageous for the timer to have a switched outlet into which the device can be plugged.

General Purpose Timers - like the GraLab 300, Time-O-Lite EZC-73, and Omega ProLab timers, have Enlarger and Safelight receptacles, so they can be used as enlarging timers. However, they cannot be set for 10ths of seconds, must be reset manually after each timing cycle, and their accuracy and repeatability are not as precise as an electronic or digital enlarging timer. Since they can be set for minutes and seconds and have a timing range up to 1 hour, they are better suited for process timing. Many people setting up a darkroom for the first time, when their budget is limited, opt for a general purpose timer. Subsquently, when they are able to purchase a dedicated  enlarging timer, the general purpose timer is used for processing only.

Types of Timers

Mechanical Timers - Years ago, virtually all darkroom timers were based on a spring powered clockwork mechanism. If used as an enlarging timer, the enlarger had to be turned on and off manually while watching the timer, which tends not to be very accurate. Eventually a few mechanical timers improved on the basic design by incorporating a switch to control the enlarger, but most mechanical timers are better suited to process timing. Since the circuitry for electronic timers can be produced so inexpensively now, and deliver much better accuracy and repeatability, there are few mechanical timers left on the market. The Kodak Darkroom Timer was sold for decades and is perhaps the best known mechanical timer.

Electromechanical Timers - have an electric motor to power the clock mechanism, but are still largely based on mechanical gears and switches. The famous GraLab 300 and Omega Audible Repeating Timer are examples of electromechanical timers.

Electronic (or "Solid-State") Timers - are based on an electronic chip and have few if any moving parts. Many of these enlarging timers use two or three mechanical rotary switches to set the time, but do not have any display for the countdown. They can usually be set for 0.1 to 99 seconds in two ranges - 0.1 to 9.9 sec., aand 1 to 99 sec. On most, a toggle type switch is used to change between ranges. On more modern version a keypad has replaced mechanical switches. The Beseler Audible Repeating Timer and Omega E-99 are two well known examples of 2-Dial type electronic timers.

Digital Timers - are electronic timers similar to those described above, but display the time using LEDs (light emitting diodes). They have become extremely popular as they are easy to read and provide a visual countdown of the elapsed time, much like mechanical and electromechanical timers with sweep hands, but with greater accuracy. The light produced by the LEDs may be a concern, but the brightness is not usually sufficient to cause a problem. However, some units provide a control to adjust the brightness and/or turn the display off altogether. Pictured above are the GraLab 450 and LPL ET-500 digital enlarging timers.

LCD Timers - Timers with LCDs (liquid crystal display) are rarely used for enlarging timers because they do not emit any light and therefore require a separate means of illuminating the display. However, since many darkroom processes can be performed with the lights on by using "daylight" developing tanks and print processing drums, LCD timers can be quite handy for process timing. The Paterson Triple Timer is an example of a battery powered 3-channel LCD darkroom timer, but a number of relatively inexpensive kitchen timers are equally capable.

Compensating Timers - are a special version of electronic or digital enlarging timer. Particularly with cold light heads, the light output of the lamps can vary depending on lamp temperature and voltage fluctuations. Compensating timers were developed to address this problem. A sensor in the lamphouse is connected to the timer to measure the relative light intensity. The timer then automatically alters the exposure time to compensate for any variation in light output.

Specifications

Timing Range - Whether an enlarging timer or process timer, check that the timing range is suitable for your requirements.

Accuracy - refers to how close the interval provided by the timer is to the time set. The figure is expressed as a plus/minus figure indicating how much the time may vary from absolute accuracy. It will most often be shown as a percentage, but sometimes is shown in fractions of a second. Obviously, the lower the figure the better. Generally mechanical timers are the least accurate, while electronic timers can be accurate to the extreme. While accuracy is desirable, it is not as important as repeatability (see below). For example, if you set the timer for 10 seconds and the actual timing cycle is 11 seconds, that's not terribly significant if you know that setting the timer to 10 seconds delivers the proper exposure.

Repeatability - This term refers to how close one timed cycle is to the next ones at the same setting. It's actually more important than accuracy. If you have determined that 10 seconds gives you the exact exposure required, you want the next exposure at 10 seconds to be identical, and not vary significantly one way or the other. Like accuracy, you'll see this expressed most often as a percentage, and the lower the figure the better.

Load - all timers that have electrical outlets for the enlarger and safelight or accessories will have the electrical capacity of those receptacles marked with a maximum figure, expressed in Watts, to ensure that you won't overload the timer. Most timers will be able to handle the electrical load of the enlargers and safelight used in a home darkroom, but it's wise to check the timer's capacity before purchase. You may also find that some electronic timers have the maximum load expressed as two figures - the higher one for enlargers with power supplies, and the lower figure for enlargers with tungsten enlarging lamps.

Features

Controls - Check that the controls will be quick and easy for you to use. Some timers have nice large knobs and switches, while others have small buttons or keypads.

Audible Signal - Most users expect the timer to indicate the end of the exposure or process step with some sort of beep or other audio signal. This is more important for process timing since the user is often occupied with something else while waiting for the step to finish. Many timers do provide this, but it can be advantageous if the signal can be switched off and/or the volume adjusted. If you might be in another room, you may need a loud signal. If you're standing near the timer, you may need only a soft alert.

Auto Reset - It can be convenient that after the timing cycle has completed the timer resets itself to the previously set time, ready for the next cycle. This is a standard feature on virtually all electronic, digital, and LCD timers. Electromechanical timers may or may not have this feature. For instance, general purpose timers such as the GraLab 300 and Omega CT-30 timers must be reset manually for each cycle, while dedicated enlarging timers such as the GraLab 400 and Omega Audible Repeating timers have the auto-reset feature.

Metronome - During an exposure, it's often helpful to be able to hear the timer counting down the seconds, particularly when doing dodging or burning-in when you're unable to look at the timer. Some timers therefore have an audible signal at each second. Since this can be annoying when not needed, it's a definite plus if there is provision to turn it off when not required. Still better is a volume control so that the loudness can be adjusted to suit the individual.

Safelight Switching - When composing or focusing, it is often advantageous to have the safelight off in order to provide the greatest clarity of the image on the easel. Most enlarging timers have a receptacle for the safelight, and normally this outlet is switched off when the timer is in the "Focus" mode and when timing the exposure. Some inexpensive timers do not provide a safelight receptacle. A few of the more deluxe timers have a switch to allow disabling of the auto switching feature.

Visibility - Different approaches have been used to make it easier to see the timer in darkroom lighting conditions. Some timers, such as the GraLab 300 and Omega CT-30, have luminescent numerals and hands. Most of the Time-O-Lite timers have black markings on a luminescent face. The Beseler Audible Repeating Timer has luminescent markings, Expose button and surround for the rocker switch. But the problem with luminescent markings is that they dim the longer the timer is left in the dark. More sophisticated timers may have buttons and controls back lit by small lamps to increase visibility. Consider the lighting conditions in your darkroom and evaluate how easy it will be to operate the timer in that type of lighting.

Accessories

Footswitch - A footswitch is a convenient accessory for an enlarging timer, since activation of the timer and thus the enlarger can be made by a tap of the foot, leaving the hands free. Some foot switches have a single pedal, which simply acts as a start switch, while other have dual pedals, with a "Focus" pedal to turn the enlarger lamp on and off for composing and focusing, and an "Expose" pedal to start the timing sequence. The dual pedal arrangement is therefore the most convenient but also more expensive, so you may want to note which type is available for the timer your're considering. Most electronic and digital timers have provision for a footswitch, while most electromechanical, mechanical, and LCD timers do not.

Final Notes 

A number of older timers, and one or two currently being sold, have only two prong non-grounded cords and outlets. Even if your enlarger and safelight have two prong power cords, we strongly recommend purchasing timers with grounded cords and receptacles. After all, the timers will be used near water and other liquids, and having wet hands is quite commonplace in a darkroom.

The performance of timers can deteriorate with age, so if purchasing a used timer, it's a good idea to test the accuracy and repeatability of the timer against a timer known to be good. A wall clock or your computer clock should be adequate for this purpose.

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