When I worked in photo lab many years ago there was one issue that came up time and time again. Customers would bring in a roll of 35mm film to be developed and and receive 4×6 prints. After looking through the prints, many times they would select one or two of their favorite images to get enlarged as a 5×7, 8×10, or larger. This is when the problem arose.
35mm film, just like nearly all Digital SLRs today, has an aspect ratio of 2:3. That is how we get 4×6 prints, 2×3 prints would be too small for us to enjoy in a frame. To enlarge an 4×6 without cropping and losing information you need to add 2 inches to the 4 inch side and 3 inches to the 6 inch side. By doing this you would get print sizes like 6×9, 8×12, 10×15, 12×18, and so on. The problem is most frames are made for print sizes such as 4×6, 5×7, 8×10, 11×14. To get prints that will fit in these frames your image will be cropped. I just don’t understand with how long the 35mm aspect ratio has been around, and how common it is, why there is still this discrepancy between print size and frame size.
Here are some images to help you understand what I am try to say.
The original 4×6 image with no cropping (this is also how an 8×12 would look):
Here is the image cropped to be printed as a 5×7, not much is lost:
If the image is cropped as a 8×10 you start to cut off important parts of the image which is unacceptable:
There are a couple of options that I would offer the customers when they faced this problem. They could buy an 8×12 frame, which are not as widely available and not made in as many styles as 8×10 frames, or they could get a 6×9 printed on an 8×10 piece of paper.
Here is an example of a 6×9 image on an 8×10 piece of paper. I added a sloppy border to make it more interesting.
I hope this helps you understand the problems and choices you have when ordering enlargements. Please feel free to contact me with any questions.