Every sensor has a certain aspect ratio. In SLR cameras it is usually 3:2 (based on the classic 35 mm format 24×36 mm), in mirrorless system cameras it is often 4:3. If the camera offers the option of setting different aspect ratios, then the entire sensor area is not used to capture the  image. Instead, only the part of the sensor area that corresponds to the set aspect ratio is “cropped”.

Ehm, I beg your pardon?

Let’s assume that the camera’s sensor has an aspect ratio of 4:3 (the whole image in the example above). If the camera is set to 3:2 aspect ratio, only the area between the red lines will be used for the image; if the camera is set to 16:9, only the area between the yellow lines will be used. So if you have your camera set to 16:9, but later need a print in 4:3 (green crop), you can only make another crop from the 16:9 format. There is not much left of the original sensor area. Accordingly, only a few pixels are available and the maximum size of the print is limited.

When should you set the aspect ratio in the camera?

From my point of view, this only makes sense if you are quite sure that you definitely only need the images in one aspect ratio. If you only want to present your images on the TV, the 16:9 setting is of course a good choice. This has the advantage that you can already see the final image frame when looking through the viewfinder or on the display and thus find the optimal image composition right away. This saves a lot of post-processing on the computer.

When should you shoot in the original aspect ratio of the sensor?

Always when you don’t know in advance what will happen to the images later. This way you always shoot with the maximum number of pixels of the camera and have all possibilities in post-processing. In particular, you can optimize the image frame for the different aspect ratios and thus have only minimal pixel losses. In addition, you can try out different variations.

And the compromise?

If you want to show your images primarily on the TV, but want to keep the option of other formats open, then you should simply shoot RAW files and JPG files in parallel. When set to 16:9, the JPGs are then optimized for the TV and the RAW files remain in the original aspect ratio of the sensor. The best of both worlds, so to speak.

As always, I’m looking forward to your comments.