Page 4 - F Stop December 2017

Aspect Ratios
By Randy O’Hara
Have you ever taken a photo to get developed? Then when you look at it some of it is cropped off, or there is white showing along one or more edges? Chances are you are using the wrong aspect ratio.
The width and the height of the sensor have a numerical value. This set of numbers is in direct proportion to the sensor (or film) size. And is displayed always as the width and its height and separated by a colon. 3:2
Although there are many aspect ratios available such as 5:3, 5:4 and 1:1 (square format), the most common aspect ratios available are 4:3, 3:2 and now becoming popular is 16:9.
Below is a breakdown of ratios.
1:1
This format is available in some digital cameras. Originally in the days of film this was a popular size with twin reflex lens cameras. Often referred to as medium format, the film negative was 6cm x 6cm in size, known as 1:1.
3:2
When we use to buy film for our cameras, it was in this format, the classic 35 mm film size. The physical dimensions were 24mm x 36mm and in the digital, is commonly known as "full frame".
4:3
This is often referred to as the Four Thirds system, or Micro Four Thirds. It is also referred to as the digital medium format. The four thirds are very commonly used in point and shoot
cameras. The popular 4:3 digital format was developed to match the then prevailing digital displays of the time, 4:3 computer monitors.
16:9
This format was developed for HDTV. Its roots go back to the sensor size 30.2mm x 16.7mm. Becoming popular, images shot in this format fit the new monitors very well. Some cameras that shoot video most likely shoot in this format.
Besides aspect ratios, we also have the terms Full frame and APS-C. As I mentioned above, full frame size is 24mm × 36mm and is the same size as the original 35mm film. APS-C is another format known as APS and the "C" is a reference to classic. This sensor is smaller at 25.1mm x 16mm. Oddly enough, this retains the same classic aspect ratio of 3:2.
So what does all this mean?
If you go to a print shop or camera store to get a 35mm picture enlarged and you want to put it in an 8x10 inch frame, a significant portion of the image will be missing. In order to get the whole image you would need to print it 8x12.
A 35mm film negative measures 2.4 x 3.6 cm, giving it a 3:2 aspect ratio. Standard size prints of 4 x 6 inches conform to this 3:2 ratio, so the prints you get match the negatives you see in the sleeves.
But no standard enlargements match the typical aspect ratio of a negative. The 'normal' sizes of 4x5 in, 8x10 in, and 16x20 inch enlargements all have a 4:5 aspect ratio, effectively chopping off 1/6 of your picture. So basically an 8 x 10 was cropped from the 8 x 12 and this causes a loss of some of the image. If you want the whole image you will need to buy a custom 8x12 frame, or at least have a matte cut to fit the image then place it in a common frame. I hope this explains a little bit on ratios and you can use this when you decide to print your image.
Source: Wikipedia