Difference Between Digital and Film Camera Lenses

Kevin Casper
Woman with camera

Have you ever wondered about the difference between digital and film camera lenses? This topic has become increasingly discussed among photography enthusiasts in recent years as the price of digital SLR cameras has fallen so drastically. Photographers who are purchasing their first digital SLR often wonder if those old 35mm SLR lenses in the closet will work with their new digital cameras. The answer is not always simple. Depending on the type of film camera you had before and the type of digital camera you have now, the lens may work or may not work at all. However, even if you get the lens to work, the real question is how well will it work? This article will try to help you understand the difference between digital and film camera lenses and will help you decide if trying to use your old lenses is worth it.

Understanding the Difference Between Digital and Film Camera Lenses

Here are some of the most important differences in lenses that you need to know:

Image Circle

The primary difference between the two types of lenses relates to what is know as the image circle of the lens. The image circle is the size of the part of the lens responsible for capturing the image and either exposing it to film or recording it to a digital sensor. On a standard 35mm film camera lens, this image sensor is usually 36mm X 24mm. On a digital camera, the image sensor is smaller, typically 24mm X 16mm. The reason for this size difference is that the piece of film that needs to be exposed by the image sensor on a film camera is larger than the sensor that data gets recorded on to in a digital camera.

Image Sensor

The reason why this is important relates to how much of the lens' image sensor will be utilized when you switch lenses, either putting a digital lens on a film camera or a film lens on a digital camera. When you're putting a film camera lens on a digital camera, for example, not all of the image circle of the lens will be utilized by the camera. Since the sensor on a digital camera is smaller, only the very center of the lens' image circle will be a part of the exposure; the areas that fall outside of that center will effectively be wasted. Often, this is not problematic, as the center of the image circle is often considered to be the sweet spot of the lens, so you will still be capturing a quality impression of whatever it is you are trying to shoot.

Digital Lens

The opposite is the case when you put a digital lens on a film camera. Since the image sensor is smaller than the film area, a smaller portion of the film area will actually get exposed. Often, a darkening of the areas outside the image sensor called vignetting will occur. While some people find this unacceptable, others think it is an interesting effect.

Economics

The bottom line is that a film camera lens will be usable on a digital camera lens more naturally than a digital camera lens on a film camera. Since film camera lenses used to be more expensive than digital camera lenses (because of their larger image circle), this issue used to come down to economics. There was no reason to use a more expensive film lens on a digital camera since much of the lens' capabilities wouldn't even be utilized by the digital camera. However, these days film equipment is getting cheaper and cheaper as digital continues to take over the field of photography, so this point isn't as relevant as it once was. And there has never been that compelling a reason to put a digital camera lens on a film camera unless you wanted to get a vignetting effect in every shot you take.

A Matter for History

This issue, like many others in technology, will soon be one for the history books. As digital SLRs continue to get released at a high number and film cameras become more and more antiquated, there simply won't be a need to wonder about this topic in a few years. Everything will be digital one day, except for a few nostalgic hold outs who still like shooting on film.

Difference Between Digital and Film Camera Lenses