When you purchase a brand new digital camera, it usually comes with a pre-installed, removable memory storage card. For most people, these memory cards are usually thought of as film for the camera. It’s basically where the photo goes when you click the shutter button and is the alternative to using classic film usually sold in packages of either 24-36 exposures. A memory card is essentially the hard drive to store your photos. Unlike a roll of film, however, the “number of exposures” you get for digital images are determined by the capacity of your memory card and the megapixels of your camera. Megapixels and image file size directly correlates — the higher the megapixels, the larger the file size of each photo.

So, how many photos can I take with my digital camera?
To answer this question, determine the number of megapixels of your digital camera and the storage capacity of your memory card. With both variables known, look at the chart below to figure out the estimated number of exposures that can fit onto your memory card. (Actual number may vary slightly. Give or take a few.)

As you can see, as the cameras’ megapixel number increase, the number of photos for a given memory card decreases compare to that of a camera with a lower megapixel.

Now that you have a pretty good idea about the number of exposures your camera and your memory cards can offer you, lets look at another variable from your camera that can also adjust that number.

Nowadays, all digital camera offers an option that allow you to select the image quality based on a setting; small (S), medium (M) or Large (L). These settings are sometimed written as the actual pixel dimension such as 800 x 600 (S), 1600 x 1200 (M) or 2400 x 1800 (L). You will also notice by selecting the smaller setting rather than the larger setting, the number of exposures from the same memory card doubles, or even triples. Many people will pose the question, why would I want less photos per memory card when I can shoot more in the same card? By changing the setting, I can magically “increase” the storage space in my memory card for more photos.

Unfortunately, it did not actually expand the storage space of your memory card, not in size anyway. Rather, by reducing the megapixels (MP) that you want for your photos, this action will give you more space. For example, if your camera offers 8MP at its highest setting and you have a 256MB memory card, according to the chart, the combination will yield roughly 69 exposures. Selecting the medium setting in your camera might reduce it 50%, or approximately 4MP. Technically speaking, that means you’ve turned your 8MP camera, into a 4MP one and allowing you to get about 118 exposures from your 256MB memory card. And so on and so forth. If you use an even smaller setting, you will certainly fit more photos. The drawback is, you are not efficiently utilizing the highest megapixel capability of your camera.

Having more or less megapixels per photo isn’t that big of an issue if you have no intention of ever getting your photos to print. As I explained in my earlier post about megapixels, a higher megapixel photo usually gives you more choices of what size prints you can select from. A lower megapixel photograph does not allow you that freedom. The quality of the photo, such as sharpness and detail, may be compromised.

Think of your memory card as a stack of 8.5 x 11 photo paper. You have the options of printing:

100 – 8.5 x 11 (8MP) high quality photo prints

200 – 8.5 x 11 (4MP) low quality photo prints (Reducing the print quality by 50% and keeping the same paper size)

200 – 8.5 x 5.5 (4MP) high quality photo prints (Cutting the print size in half, but retaining the highest quality)

400 – 8.5 x 5.5 (2MP) low quality photo prints

In the end, it all comes down to the question of what your ultimate use are for the photos. It is a choice between taking more photos, or taking fewer, but higher quality photos. In addition to the megapixels that determine the quantity of pictures you can take for a given memory card, other variables such as file format (JPG, TIFF, RAW) and image color depth (8 bit, 12 bit, and 16 bit) will also affect that exposure amount. Which, of course, will need a post of its own for that discussion.

I hope this was helpful. Any feedback or questions will be greatly appreciated.

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