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The Arcminute Rule

Well, so my blog isn't entirely about data networking and beer, here's something practical. I decided to try to find an online service where I could upload some photo I took and have it printed out and framed on canvas using those fancy canvas printers. so far makes sense, right? Well I wanted something big like 72 inches wide for the bedroom, so I then thought hmmmm I wonder if my photos are hi enough resolution but ( just like in Latency! Sorry for the data network testing reference!! ) resolution is meaningless, utterly, totally useless, a word like flim flam or hoosiwatsit. We need to know how expensive a camera you need to buy to take photos that print out on 72 inch wide canvas with acceptable viewing, and, more importantly, if the photos I took in 2001 with whatever mid-range cheap camera that fitted into an underwater housing back then was able to do. And, again, I am pretty useless at most things but I sure am good at searching the web so I came up with the coolest thing, the kind of thing you'd have to take a photography class (and a good one at that) to find, an amazing bit of information - and not a web page, not a PDF, just an individual post in a thread in some forum, the source is this and the post is this, my plagiarism flagrant as usual but if something is valuable, I archive it here like a historian, and will take it down if the owner wants or will pay them if they want, for whatever it is is worth, but you'll appreciate not having to click on a broken link when you need to print out a big canvas photo - now, bear in mind, this blog is for geeks - if you don't like crunching numbers go back to reddit, here you go, from MacRumors http://forums.macrumors.com/archive/index.php/t-884993.html and posted by "anubis" (and of course, owned by the poster)

"In general the human eye can resolve details that subtend one arcminute or .00029 radians.

For something 12 inches away that corresponds to a spot subtending .0035 inches. So for example, if the sensor is 3000x4000, and the print size is 9x12 inches, then each pixel would correspond to a spot on the print .003 inches.

This assumes perfect printing, perfect vision, and other nonsense. People blow things up much larger than that though, especially if the print is to be viewed on a gallery wall and people will be at least 3-4 feet away. You can use the one arcminute rule to determine how the print will look given a certain number of megapixels and the viewing distance."

OK so now armed with this information, and some New Belgium "Dig" seasonal ( and boy, have I ever been digging today ( literally ( in the garden ) ) ) here is my conclusion about my 72" wide print that I hope to.

Inputs: distance of the viewer, I think 4 feet is plenty. Let's go with 4
Dimensions of print: 24" high x 72" wide
My Camera MP in 2001: about 2MP
Conclusion: will look like a Matisse that got rained on before it dried.

BUMMER