Aspect Ratio Quick-Tip

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I had someone who was looking at purchasing their first dSLR ask me what the Aspect Ratio was and why it mattered. This is a good question and I thought it would make an excellent Hustedia.com Photography Quick-Tip.

The aspect ratio in its most basic form is used to describe the relationship between two sides of a rectangle. Obviously, a square has 4 equal sides so the aspect ratio is always 1:1 in. However, in a rectangle, it’s the ratio of one side compared to the other (Length vs. Width). It has nothing to do with the actual size or measurement of the rectangle, only the ratio of its sides when compared to one another. Let’s say you took a picture that resulted in an image size of 1600 x 1200. If you divide by the largest common denominator, in this case 400, you would get a ratio of 4:3 (1600/400 = 4; 1200/400 = 3). Another example would be that you had an image that resulted in 1280 x 1024. The largest common denominator is 256 which would result in 1280/256 = 5; 1024/256 = 4 for a final ratio of 5:4. I happen to shoot with a 4:3 ratio camera as I shoot the Olympus brand which is a member of the Four-Thirds standard for digital imaging.  However, a vast majority of dSLR camera sensor today are in the 3:2 ratio format.

Which ratio is best? None of them. There is no ‘best’ in my opinion as there are variables to consider whether you buy 3:2 or 4:3 ratio cameras, in particular when it comes to printing. Let me explain briefly why this is the case.

One of the more common print sizes for images is 4×6. Obviously, this lines up perfectly with the 3:2 aspect ratio because 3×2 = 6 and 2×2 =4 so the image can easily be printed without cropping out any of the image. This is also the case with 12×8 size prints since 3×4=12 and 2×4=8, so the image can again work without any cropping. The problem arises when you want to print some of the larger sizes such as 5×7, 8×10, or 11×17. For example, if you take the 3:2 aspect ratio and multiply it by 4, your result is 12×8 as mentioned above. This does not align with a 10×8 print size as the longest sides do not match.  In order to print a 10×8 of your 3:2 aspect ratio image, you will have to crop the image in order to get it to fit. You are going to lose 2 inches from your original image. If you did not do this, your image would be distorted and all bunched together or spread out. Have you ever taken a standard definition television signal and ‘stretched’ it out to fit your new widescreen HD TV? It’s a very similar concept!

With a 4:3 aspect ratio sensor camera, a print size of 4×6 would result in a necessity to crop the image because there is no way to make a 4:3 ratio equivalent. However, even though you will still have the need to crop the image to print at 5×7 or 8×10, the amount of image lost is significantly less than if you were using a 3:2 aspect ratio sensor. Personally, I love to print 12×9 size images, so the 4:3 ratio works extremely well for this as 12×9 results in a 4:3 ratio (12/3 = 4; 9/3 = 3). Although there are many other issues to consider before purchasing your dSLR, including other criteria related to sensor sizes, if you plan to print larger images, you “may” want to consider a 4:3 aspect ratio camera.

Until next time!