Photographers have traditionally relied on film for image acquisition, but all that has changed with the advent of digital imaging technology. So does film still have a place for the modern photographer in today's brave new world of binary realms and digital frontiers? In this tutorial we'll look at the pros and cons of digital and film cameras for night photographers.
When I first began my career as a cameraman, film was the only available option. These days film has been largely replaced with digital technology, but there are still some situations where it might offer certain advantages to the night photographer.
There are basically two types of film: colour reversal film (often called a negative) and slide film. The latter generally offers superior image quality, and you can choose either colour or black and white varieties.
There are many different film emulsions to choose from, ranging in speed from ISO 25 up to ISO 6400. This ISO rating refers to the sensitivity of the film, with lower numerical values equating to slower speeds that require more light.
A film rated at ISO 100 requires twice as much light as a film rated at ISO 200. To get the same exposure you have to double the shutter speed or open up the lens one full f-stop. The benefit of using slower speed rated films is that they have a finer grain structure, equating to an increase in resolution.
As digital technology continues its relentless march forward, film has been left behind, and there are far fewer film stocks available now than there were around the turn of the century. The venerable Kodachrome slide film is a case in point—it was withdrawn from sale a few years ago, and parent company Kodak filed for bankruptcy.
So what can film offer that digital does not?
One of the considerations with any digital device is that they require electricity to function. These new camera technologies are driven by power-hungry image sensors and integrated circuits, and without power they simply can't take pictures.
With an old mechanical film camera, you don't need batteries or an AC power supply for the camera to function. The only battery these cameras require is used by the exposure meter, and even if it goes flat you can still operate the shutter and take a photo.
By using a film camera with a cable release, you can set exposure times of several hours' duration. This is very useful if you wish to do star trails, or take photos where there is very little available light and ultra-long shutter speeds are required
Another advantage of using film is that you don't have to worry about digital file storage requirements. Again, this can be important if you are in a remote location where you don't have access to mains power.
If your camera's storage card begins to fill up, you will need to archive those files to a device such as a hard drive, computer, or tablet, and these will require AC power or DC batteries to operate. However, storage cards are becoming cheaper and larger capacities more common, so carrying many extra cards with you is a viable option.
Film also has some disadvantages, the primary one being cost. It is expensive to shoot film: not only do you have the expense of paying for the film to begin with, but you also have to pay the processing costs to have your pictures developed afterwards.
If you wish to have your images available for the web or for computer displays, you will also need to "digitise" the film to transfer it from the analog to the digital realm, and this is yet another expense that you will incur.
There is also a much longer learning curve when shooting film, as you don't have the instant feedback you get with digital cameras. You won't know the results of shooting on film until after you have your work processed, and you cannot review your work at the time of shooting as you can with digital.
You may also come across a problem inherent in film called reciprocity failure. Because most films are designed for shutter speeds between one second and one 10,000th of a second, any shutter speed outside of these parameters may require exposure compensation or colour correction to negate the effects of reciprocity.
In the case of exposure compensation, you may need to double the length of time the shutter is open, or open up the lens aperture by one stop to get correct exposure. Film may also exhibit a colour shift due to reciprocity, and this will require a colour correction filter on the lens to restore accurate colour balance.
So now that we have covered film, it is time to move into the 21st century and talk about digital cameras. This newer technology offers so many advantages that digital acquisition has almost entirely replaced film as the medium of choice for today's photographer.
When digital cameras first arrived on the scene they were fairly primitive in their capabilities. Resolution was typically only a few megapixels, as sensor technology and digital signal processing were in their infancy.
Image quality was inferior, and there were many shortcomings such as poor low light capabilities and a lack of dynamic range, especially when compared to medium or large format film images.
The first digital camera I owned was a Nikon D50 with a 6 megapixel CCD image sensor. I bought this camera simply to experiment with this new technology, but it soon became quite apparent to me that digital image acquisition was a game changer.
The ability to review photos instantly to check focus, exposure, composition and colour balance made the job of a photographer far easier. It helped to accelerate the learning curve, leading to less guesswork and fewer mistakes.
This new technology also opened up creative possibilities that were not possible or were far more difficult with film cameras. The ability to shoot time lapse sequences, create multiple exposure compositions, and use high dynamic range imaging made digital cameras a very exciting proposition.
At the heart of a digital camera is its image sensor, and it is this sensor that captures the light coming through the camera's lens. Digital sensors come in a variety of different types, including CCD, CMOS, and NMOS. Resolution ranges from a few megapixels up to the gigapixel capabilities of sensors found in scientific imaging devices such as telescopes.
The resolution of the image sensor is dependent on the number of pixels present, but as the pixel count increases, other image quality factors like the sensor's low light capabilities are compromised.
One way camera manufacturers have negated this effect is to maintain the same number of pixels but increase the physical size of the sensor, thereby increasing its light-gathering ability.
When choosing a digital camera for night photography, it is important to consider the quality of the image sensor, as low light conditions are common. It is therefore a good idea to consider one of the larger-sized image sensors, such as those found in full frame cameras.
A full frame sensor is equivalent in size to a 35 millimetre film frame, and will give you amazing low light capabilities. However, full frame cameras can be quite expensive and are less forgiving of the lenses' optical quality, so your investment will generally be higher for both the camera body and the lenses you wish to use.
If your budget won't allow for the the purchase of a camera with a full frame sensor, then I would recommend you look at cameras with either an APS-C or Micro Four Thirds size image sensor, as even these cameras are more than capable of creating images with very high resolution, good low light performance, and excellent dynamic range.
Previous generations of digital camera had certain limitations when being used in low light conditions, such as high levels of digital noise, but modern digital cameras have addressed these problems. Performance now is far superior to that of cameras available even a few years ago.
These days we are absolutely spoilt for choice, and today's low-cost entry-level models have image quality that rivals or exceeds previous generations of expensive professional cameras. All you need is the talent and knowledge to exploit their capabilities.
I rarely shoot film these days, but I am glad to have had experience in this type of photography, because I learnt not to waste exposures due to the expense involved, and I believe it helped to sharpen my skills considerably.
In the next part of this series, I'll cover equipment for night photography and what I think is the most important investment you will make in your camera system: your lenses.