Choosing Resolution Size on a Canon EOS Rebel T3 Series Camera
To decide upon a Quality setting (or photo resolution size) for your Canon Rebel T3 or T3i, the first decision you need to make is how many pixels you want your image to contain. Pixels are the little square tiles from which all digital images are made; pixel is short for picture element. If your photo viewer has a zoom tool that enables you to greatly magnify an image, you can inspect the pixels in your own photos.
The number of pixels in an image is referred to as its resolution. Your camera offers five resolution levels, which are assigned the generic labels Large, Medium, and Small (1-3) and are represented on the list of Quality settings by the initials L, M, and S (1-3). The table shows you the pixel count that results from each option. (If you select Raw as your Quality setting, images are always captured at the Large resolution value.)
|L||Large||5184 x 3456 (18 MP)|
|M||Medium||3456 x 2304 (8 MP)|
|S1||Small 1||2592 x 1728 (4.5 MP)|
|S2||Small 2||1920 x 1280 (2.5 MP)|
|S3||Small 3||720 x 480 (0.35 MP)|
In the table, the first pair of numbers shown for each setting in the Pixel Count column represents the image pixel dimensions — that is, the number of horizontal pixels and the number of vertical pixels. The values in parentheses indicate the total resolution, which you get by multiplying the horizontal and vertical pixel values. This number is usually stated in megapixels, or MP for short. The camera displays the resolution value using only one letter M, however. Either way, 1 MP equals 1 million pixels.
To choose the right setting, you need to understand the three ways that pixel count affects your pictures:
Print size: Pixel count determines the size at which you can produce a high-quality print. How many pixels you need depends on your photo printer, but a good minimum threshold is 200 pixels per linear inch, or ppi, of the print. To produce an 8 x 10 print at 200 ppi, for example, you need a pixel count of 1600 x 2000, or just less than 2 MP. For professional publication, you may be required to submit photos at a higher ppi.
Screen display size: Resolution doesn’t affect the quality of images viewed on a monitor, television, or other screen device the way it does for printed photos. Instead, resolution determines the size at which the image appears. Just know that you need way fewer pixels for onscreen photos than you do for printed photos. In fact, the smallest resolution setting available on your camera, 720 x 480 pixels (S3), is plenty for e-mail sharing.
File size: Every additional pixel increases the amount of data required to create a digital picture file. So a higher-resolution image has a larger file size than a low-resolution image.
As you can see, resolution is a bit of a sticky wicket. What if you aren't sure how large you want to print your images? What if you want to print your photos and share them online? Here's some advice, to keep you better safe than sorry:
Always shoot at a resolution suitable for print. You then can create a low-resolution copy of the image for use online. In fact, your camera has a built-in Resize tool that can do the job for you.
For everyday images, Medium is a good choice. Keep in mind that even at the Medium setting, your pixel count (3456 x 2304) is far more than you need to produce an 8 x 10 print at 200 ppi, and almost exactly what you need for an 8 x 10 print at 300 ppi.
Choose Large for an image that you plan to crop, print very large, or both. The benefit of maxing out resolution is that you have the flexibility to crop your photo and still generate a decent-sized print of the remaining image.