For many people, the differences between digital cameras and film cameras are clear: there’s no film, memory cards are reusable and you get the results right away. What more do you need to know?
In fact, it helps to know quite a bit. There are a number of facts that look small but actually have an important influence on your pictures, the way you take them and what you should do with them.
Here are some of the most important.
1. JPEG Images Lose Quality Every Time They’re Saved
JPEG (which stands for Joint Photographic Experts Group — the committee that created the format) is not just a means to store images. It’s also a way of compressing images. Each time an image is opened and saved in the JPEG format, the compression tosses out a little more information, reducing the size of the image but also lowering its quality. The more you save, the worse the image gets.
That might be fine for uploading to the Web or viewing family snaps, but when you’re shooting for money, it pays to shoot in RAW so that you have a permanent “negative” that remains high quality.
2. Sensor Size Matters
The light-recording sensor in a digital camera tends to be much smaller than the 36mm x 24mm frame standard in a 35mm camera. To record the same amount of information as a film camera then, the lens on a digital camera has to use a shorter focal length.
Photo.net has a detailed description of what that means for picture quality but the bottom line is that the smaller the sensor in your digital camera, the lower the quality of the information reproduced through the lens, especially at high f-stops.
3. Commercial Users Can Have Prohibitively High Quality Demands
Although some photography buyers will be happy to purchase images taken on the $500 digital SLRs — and even on the lower quality cameras — used by serious hobbyists, many outlets do expect much higher quality. Niche stock company GoGo Images, for example, expects its photographers to supply 50MB images shot on full frames.
That means that some commercial photography opportunities will be unavailable to all but the most dedicated — or professional — photographers.
4. Few Digital Cameras Can Compete with the Resolution of Film Cameras
According to Hewlett Packard, if you could measure the resolution of 35mm film in pixels, it would be around 20MB. Even a simple film camera then would have the quality of a top-end digital camera — and only a top-end digital camera can produce the quality of a standard film camera.
5. Many Leading Photographers Still Shoot on Film
Perhaps it’s not too surprising then that a number of top professional photographers have turned their backs on digital photography, and are still putting their images on celluloid. (We highlighted a number of them here.) Whether that’s for convenience or quality, they prefer to skip the ease of storage and delivery in favor of old fashioned darkroom work.
6. You Can Have Too Much Resolution
Higher resolutions might be necessary for some photography jobs and they always give more options, but you don’t need 20MB images for every purpose. In fact, there are times when high resolutions can work against you.
Print a high-res image on a low-res printer for example, and the printer will downgrade the image itself in order to process it. That’s bad enough but upload a high-res image to the Internet, especially on Flickr, and there’s a greater chance that someone will steal it.
Keeping your images small and low-res is one of the best ways to limit its use for picture thieves.
7. The number of Megapixels in your Camera isn’t the Number of Megapixels in your Camera
Buy a 4-megapixel camera and you’ll be told that you can shoot an image that’s 2,240 pixels wide and 1,680 pixels high without loss of quality. That sounds impressive enough but 2,240 multiplied by 1,680 is 3,763,200 pixels. Where did the other 236,800 pixels go?
The answer is that they were lost to circuitry needed to record the light hitting the sensor and it happens on every size of camera. It’s a bit like buying a new computer. No matter how large the memory on the box, you always have to round it down a bit to get your true figure.
8. Megabytes aren’t the Same as Megapixels
The difference between the stated number of megapixels in a digital camera and the actual number is confusing enough. The similarity between megabytes and migapixels is even more confusing. They’re not the same. One megapixel is one million pixels; one megabyte is 1,048,576 bytes of computer memory.
A camera may require more than one byte to store one pixel so again, you could end up with less than you thought you were paying for.
Digital cameras aren’t very confusing but when you’re investing in equipment and hoping to sell images, it’s worth knowing exactly what you’re buying.