What is a darkroom safelight?
A safelight is a type of lighting fixture used to provide working light in photographic darkrooms. By definition, the safelight 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 radiology), 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. Modern panchromatic photography film is sensitive to all parts of the visible light spectrum, so no safelight is suitable for it. Such materials may sometimes be handled under infrared light with suitable optical aids.
On the other hand, orthochromatic film is only sensitive to blue and green light and can be safely used under a red safelight. This is also the case with most black and white printing papers, although there are some specifics which we will cover below.
Beware that the suffix safe may entail a false sense of security. Most photosensitive materials will eventually fog under most safelights, given enough exposure. Different papers and films vary greatly in sensitivity, and will behave differently under the same safelight. It’s a good practice to always do your own tests before you commit to any serious darkroom work with new equipment and/or materials.
What are the different types of darkroom safelights?
There are several different types of safelights on the market, and they differ mainly in their light filtering mechanism. There are two principal approaches to a safelight: a full spectrum lightsource behind a filtering medium or a narrow band light emitter. For most of the history of photographic printing, safelights have been predominantly of the former type. Only recently, with the rapid development of narrow band LED light sources, did the latter kind emerge. Today, both are readily available, either new or on the second hand market. Here are the most popular safelight types with their advantages and disadvantages:
Interchangeable filter safelights
Probably the most traditional type of darkroom safelight fixture consists of a housing with a bulb socket and a filter frame. One such model is the Kaiser 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 photographic safelight is the bare bulb safelight like the Delta 1 pictured above. It is the simplest kind of safelight, as it is just a regular light bulb coated with filtering material.
Advantages of safelight bulbs are simplicity, flexibility and affordability. They fit in all standard fixtures. 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. This makes them a potentially 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. 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.
Despite it’s traditional roots, analog photography benefits from the latest developments in lighting. The 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 require no filtering and there is no filter factor 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 lamps also makes them very low maintenance. A typical LED emitter is rated for around 50,000 hours of operation. As there are no filters to fade, an LED safelight should perform consistently throughout it’s lifetime. 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. Generally LEDs allow much higher darkroom illumination for far longer than traditional incandescent safelights. Of course, as with any other safelight lamp, you need to test your particular setup before you begin printing.
Darkroom 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.
The humanly visible portion of the light spectrum covers a wave-length range from approximately 380 nm up to 780 nm. A typical red safelight filter, like the Kodak 1, transmits light with a wavelenght above roughly 600 nm, in Kodak’s case all the way up to infrared. An amber safelight (Kodak OC for example) sits lower at about 590 nm and has (somewhat limited) use in color darkroom processes. Dark green safelight filters, like the Kodak 3, let through light around 510nm and are used with some panchromatic materials.
Choosing the right safelight
Choosing the right safelight is a crucial step in equipping a photography 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. It will narrow down your selection considerably before you even get to 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 want to go with the manufacturer’s recommended 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. A classic Kodak 1 safelight filter will do nicely with this paper. 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. In this example you might want to stick between 600nm and 650nm. Anything above 650-700nm starts getting outside of the visible spectrum and into infrared.
You can now use this information to narrow down your selection of safelights. Always check the spectral characteristics in the fixture manufacturer’s specifications to confirm that the unit is suitable for use with your materials.
Now you’ve determined what sort of spectrum output you need and have narrowed the selection down. Next, you can move on to selecting the best type of safelight for you. This is more of a personal preference than anything else.
Are you are just dabbing in darkroom printing for the first time? If you 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. Alternatively, another option can be a dedicated LED safelight. Some advanced models like the Heiland above offer selectable spectral outputs within one unit, including a white light mode for regular viewing.
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. Do keep in mind that most LED bulbs cannot be dimmed, so plan accordingly.
The one area where safelight illumination control matters most is the enlarger baseboard or easel. If the safelight intensity in this area is too strong, you will have a hard time seeing and focusing the image projected by the enlarger. It might also interfere with the use of a focus finder or when doing any dodging and burning. Furthermore, you will increase the risks of paper fogging with prolonged exposure.
Safelight Q & A
Can any red light be used in a darkroom?
Well, yes and no. If you get a random red-tinted lightbulb or LED emitter, you may or may not be able to successfully use it as a safelight. You might get lucky and it may just be the right spectrum to do the job, or it may ruin that precious box of Ilford paper. We do not recommend just buying a bunch of red lights and hoping one of them works, but if you stumble upon one you want to try out, test it extensively before you do any serious darkroom work with it.
What safelights are used in radiology?
The light sensitive materials used in radiology are predominantly green or blue sensitive, and as such can safely be used under a red (>600nm) safelight illumination. However, any radiology technician should consult the film manufacturer’s guidelines before commiting to a working setup.
Is there a safelight that can be used when developing film?
When it comes to regular modern photographic film, the short answer is no, there is no safelight for that. The vast majority of photographic film used today is what’s known as panchomatic, which means it’s sensitive to all parts of the visible light spectrum. Therefore, no light that you can see can safely be used when developing such film.
The only exceptions to this are specialist ortochromatic films typically used in radiology, industrial imaging or certain printing processes. These films are blind to parts of the visible spectrum, which allows for a safelight to be used in development. Photographers that employ such films for pictoral use may be able to develop them with a suitable safelight.
The only way to observe the development of panchromatic film is by use of infrared night-vision goggles, such as used by military or hunters.
2 Comments on “Safelight”
I got a 50 watt red bulb from pet store for heating light sensitive reptile cage at night. Could that be used for darkroom?
If you already have the bulb, do some testing, it might just work! As long as it does not fog the paper, it’s perfectly fine to use any red bulb. This type of bulb is not meant for lighting and it will be difficult to find any manufacturer data regarding the spectral output, so your best bet is to run your own tests.