I want to print out either of these two Milky Way Photos on a 12x18 size photograph (Or vice versa if it is horizontal).
The problem I'm worried about is the amount of grain which would show up. The photos look fine on my laptop (MBP Retina) but I'm not sure about them being almost twice the size. Due to them being astro photos, grain is just part of their nature. Even with stacking etc. I've never printed a photo this large before and do not want to spend all the money to have it show up with a lack of detail. Do any of you have any advice for printing them? I'd appreciate any ideas. (Photoshop, printing services, canvas vs paper)