What is a safelight?
A safelight is a type of lighting fixture used to provide working light in photographic darkrooms. It is a light source emitting light in an area of the spectrum that does not affect the light sensitive materials for which it is designed.
A safelight is essential in any darkroom, as it provides illumination without affecting the photographic materials. Many darkroom processes would be impossible or impractical without a safelight. Safelights are also utilised in most other fascilities handling photosensitive materials like medical imagery labs (x-ray), lithography printing outfits and others.
There are different types of safelights for different light sensitive materials. Depending on the type of material, there may or may not be a safelight available for it. As an example, modern panchromatic photography film is sensitive to all parts of the visible light spectrum, and therefore no safelight is suitable for it. Such materials may sometimes be handled under infrared light with suitable optical aids.
What are the different types of safelights?
There are several different types of safelights on the market, and they differ mainly in their light filtering mechanism. Here are the most popular types with their advantages and disadvantages:
Interchangeable filter safelights
Probably the most traditional type of safelight consists of a housing with a bulb socket and a filter frame. One such model is the Arkay Darkroom Safelight pictured above.
The main advantage of this design is the flexibility it provides. The interchangeable filters to allow the safelight to work with a variety of light sensitive materials.
A disadvantage of this type of safelight is it’s need for maintenance. Safelight filters fade with use, and need to be monitored and replaced as needed. Filter manufacturers provide guidelines, but testing with your particular setup and materials is best. Fading does happen gradully and can sneak up on you, so fog testing must be done at regular intervals.
Bare bulb safelights
Another traditional type is the bare bulb safelight like the Delta 1 pictured above. It is the simplest kind of safelight, as it is a regular light bulb covered with filtering material.
Advantages of this design are simplicity, flexibility and affordability. The bulbs fit in all standard fixtures, so you can have for example a safelight desk lamp with the twist of a wrist. Bare bulbs are also cheaper and smaller than dedicated safelight housings, so they might be a better option for the casual darkroom user. They are also a great option for users that don’t print in dedicated darkrooms, but have to adapt other spaces.
The main disadvantage of the bare bulb safelight stems from it’s all-in-one approach. An interchangeable filter safelight can take any old bulb you have lying around the house, provided it is within it’s fitting and wattage limitations. On the other hand, if your bare bulb safelight blows and you do not have a spare your printing session might come to an abrupt end.
Just like the interchangeable filter type, the filtering material of the bare bulb is also prone to fading, so testing and monitoring is again necessary.
Newest addition to the safelight family, LED safelights vastly outperform their old school siblings. The biggest advantage of LED as a safelight is the sharp spectral cutout. What this means is that a typical LED emitter with peak output (for example) at 600nm emits virtually no light outside 590nm to 610nm.
A properly selected LED is therefore a perfect safelight source, as all the light that is emitted is within the safe spectrum. Such LEDs requires no filtering and there is no filter light loss. Compared to an incandescent bulb behind a filter, where a large percentage of the light is absorbed by the filter, LEDs are extremely efficient. Subsequently, LEDs also produce very little heat in operation, which can be very benefitial in a small, non air conditioned darkroom.
The lack of filters in LED safelights also makes them very low maintenance, there are no filters to fade. Furthermore, a typical LED emitter is rated for around 50,000 hours of operation. Depending on the amount of darkroom printing you do, this might make an LED the only safelight you ever buy.
A key advantage of the narrow spectral output of LEDs is that you can make your darkroom as bright as you want. Of course, testing needs to be done as with any other safelight, but generally LEDs allow much higher darkroom illumination for far longer than traditional incandescent safelights.
Safelight colours and spectrum ranges
While the classic red safelight is the vastly recognizable darkroom staple, it is far from the only type of safelight used. Digging deeper, you will stumble upon safelights described as amber, brown, yellow-green and others. In reality, the colour of the safelight is just an easier (and less accurate) way to describe the spectrum range of light it outputs.
Choosing the right safelight
Choosing the right safelight is a crucial step in equipping a darkroom, regardless if it’s a permanent or a temporary setup. So what exactly do you need? There are several questions you need to answer to select the best option for you.
The first step to select the best safelight is to determine what color (or spectrum range) light you need. This is the most important characteristic and it might narrow down your selection considerably before you’ve even reached the other selection criteria. As we’ve discussed above, safelights come in many different flavors. So how do you know which one you need?
A good starting point is consulting the manufacturer recommendations of the materials you plan on using. Virtually all photographic materials manufacturers provide data sheets for their products, and, among other useful things, these sheets contain safelight guidelines. Here’s what Ilford has in their Multigrade RC Papers technical information sheet:
ILFORD MULTIGRADE papers can be used with most common safelights for black and white papers. The ILFORD safelights are especially recommended as they generally allow darkrooms to be brighter, but completely safe. For direct lighting, do not expose the paper to the safelight for more than 4 minutes, and the distance between the paper and the safelight should be a minimum of 1.2 metres/4ft.
This is not very concrete, so we can dig a little deeper. If you don’t just want to go with the recommended manufacturer’s unit, or if one is not available you need to find a suitable substitute. To do this correctly, you need to find out the spectral sensitivity of the photosensitive product you want to use. In this case, in the same data sheet Ilford provides the spectral sensitivity of it’s Multigrade paper:
From the chart above, we can see that the paper is sensitive to the light spectrum from about 370nm to 550nm. What this means is that any safelight filter that filters out these wavelenghts is suitable for use with Ilford Multigrade. Looking at this from an LED safelight point of view, any fixture emitting light from about 600nm upwards (to be on the safe side) is fine. Bear in mind that the higher you go, the less visible the light will be, as it gets outside of the visible spectrum. In this example you might want to stick between 600nm and 650nm.
You can now use this information to narrow down your selection of safelights. Make sure to check the spectral characteristics in the fixture manufacturer’s specifications to confirm that the unit is suitable for use with your materials.
Once you’ve determined what sort of spectrum output you need and have narrowed the selection down, you can move on to selecting the best type of safelight for you. This is more of a personal preference than anything else.
If you are just dabbing in darkroom printing for the first time and just want to try out a few prints in a blacked out bathroom, you might want to start small. A bare bulb incandescent or LED safelight is the easiest and cheapest option. You can just screw those into any fixture and be done with it. Once you are done printing, screw a regular bulb back in and no one will ever know you’ve been printing.
If you are equipping a dedicated darkroom and intend on doing various processes there you might need something more durable and flexible. A classic interchangeable filter fixture with the corresponding filters for your processes is a comprehensive solution. Another option can be dedicated LED safelights, some of which offer selectable spectral outputs within one unit.
In the darkroom, brighter is almost always better, within reason. If you are wondering wheter to go for a brighter or a dimmer bulb, always err on the side of brigher. You can always dim down the light with a filter, a dimmer switch or simply by bouncing it off a wall or ceiling. Making do with a dim bulb is a bit trickier.