I have a Canon 60D (18mp, 22.3 X 14.9mm sensor). I plan to start having some of my images printed. Although I understand that there are a variety of factors that will affect maximum print size, I am trying to come up with a guideline (or better yet, a reference chart) to determine maximum print size without visible pixelation at "normal" viewing distances. I might add that I shoot in RAW format at ISO 100-200 (whenever possible). Also, dpi would be 240-300.
Thank you kindly for any guidance.
Hi Kit,
It mostly depends on the quality level you need, based on visual acuity, and viewing distance.
I've released
a free web-based tool to calculate things like that (and much more).
Section 1. of my tool is all you need to answer your question. Basically you can print your 60D files at 45x30cm (17.7x11.8 inch) size when you need to allow close (normal reading distance) inspection, and e.g. 150x100cm (59x39inch) when viewed from 1 metre (3.28 feet) distance. This assumes uncropped images and normal 20/20 vision.
For the actual output file size, and before output sharpening, you need to use a good resampling tool and resample to the native resolution of the printer that's going to be used, usually 300 or 360 PPI, or even 600 or 720 PPI. Sharpening at that output resolution will give the highest quality results, but do check the actual printer specifications if you use off-site printing facilities.
Cheers,
Bart