Aspect ratios in photography refers to the ratio of the width to the height of an image. An aspect ration might be 4 to 3 (standard DSLR image) or 1 to 1 which gives you a square image.
I was watching one of Scott Kelby’s videos, not sure which one as they sometimes seem to blend together. In the video he was talking about what was the proper aspect ratio for a panorama. While there isn’t any real rule for the perfect pano, he did come up with an aspect ratio of 2.39 to 1. To transform you image into a panorama you need to change the photo’s aspect ratio. To set up a custom Aspect Ratio in Light room select a photograph and press the R key or click on the dotted line box under the histogram when in Develop mode.
Next to the lock is the current crop ratio (2.39 x 1) in this instance. To add a custom ratio click the up/down arrows between the current ratio and the lock which will pop up the select an aspect ratio menu. There are some standard ratios already defined for you. You would use the 1 X 1 ratio to crop to a square.
When you click OK the aspect ratio will be saved and can be used any time you want. Remember it is an aspect ratio and is not related to at actual pixel counts of the crop. All the 2.39×1 aspect ratio says is for every 1 pixel high the selected area is it will be 2.39 pixels wide.
And here is a standard D600 full frame image cropped down to the saved panorama aspect ratio.
While panoramas most often bring to mind landscapes, this aspect ration can be used with a still life too.
I think the 2.39 x 1 aspect ratio is quite pleasing. It’s a good place to start if you have an image with a boring sky or maybe to much yawn inducing foreground.