It's been a long time since I took prints from my digital images .Can I ask someone to remind me which print sizes are full frame i.e. no cropping? I have 6x4 inches 8x6 and 10x8 in my mind and not others such as 7x5 inches? Thanks
Going to depend on camera. If as I assume you mean most 35mm cameras such as say my Canon 5DMKIII then its a 2:3 aspect ratio but some use the 4/3 now. Nor sure it matter though as it is what crop suits the image Anyhow 6x4 9x6 12x8 should all work without cropping (but if they don't tough I'm not offering a warrantry!)
Why not use PS or similar to work it out. Just resize the short edge to 10cm...and see what the long edge comes to. Or use any of your potential sizes....put in the short edge....see what the long edge comes out at.
You can of course set the cropping tool to any ratio you want and use that to play with your image to get the effect you are looking for.