It’s a tough topic to understand. Shoot, took me a while to finally figure it out. But when I did, it became so simple. Here are the three (required) determining factors:
Pixel size of the photo
DPI (dots per inch), a measure of print quality
Physical size of the print
Asking “Do you shoot at 300dpi?” is similar to asking a bus driver if it’s going to be a long ride… Compared to what? Are you taking the bus home from work, or are you taking a bus from New York to Los Angeles? It’s like asking a cook if they made enough food to feed a classroom… Is it a college classroom with 350 grown adults, or is it my 11 year old brother’s classroom of 25 children?
Here is an example of a question that can be answered:
“Am I going to be able to print this photo in 5×7 at 300dpi?”
And the answer depends on the pixel size of the original photo.
Pixel size of the photo depends on the camera used to take it, and the settings on the camera at the time the photo was taken. Once the photo has been taken, there is nothing you can do to “enlarge” it beyond its capabilities. You can only reduce the print size from that point on.
Pixel sizes can range from 640×480 to 4752×3168 and higher. The point is that you can print any photo at 300dpi. Here are some numeric examples:
Pixel to Print Size @ 300dpi:
640×480 – 2.13 in. x 1.6 in.
1600×1200 – 5.33 in. x 4 in.
4752×3168 – 15.84 in. x 10.56 in.
There are many other factors that can affect the quality of a printed photo. This is just a basic pixel to print size explanation. I hope it clears up some of your confusion.