When looking to get your photographs printed, bear in mind that companies print in specific sizes so you need to adjust your prints to fit the ration, otherwise you may find that your photos come back cropped in a way that you wouldn’t necessarily want them to be.
Ratios of photos from DSLR camera are 3:2, so anything measuring 6″x 4″, 7.5″* x 5″, 9″x 6″, 12″x 8″, 15″x 10″, 18″x 12″ etc. won’t need any cropping.
(*NOT 7″ x 5″)
Other proportions / ratios:
- 1:1 = square
- 4:3 = old TV screens, point and shoot cameras
- 4:5 = old large format cameras
- 9:16 = widescreens
In Photoshop, you can select the ratios at which you wish to crop and then move the photograph until you have selected where you want to crop. In the example below, you can see that a ratio of 1:1 has been chosen and Photoshop is prompting you to select a square area to crop@
Resolution is to do with how you store pixels. Note that the pixels per inch ( ppi) (eg. 72ppi, 300ppi) has nothing to do with the quality of your photograph. It jut means that there are more pixels in your photo.