How big can I print this?

Someone with good eyesight is said to have 20/20 vision. This means that at 20 feet they can distinguish two dots separated by a visual angle of one arc minute, 1/60 degree (roughly 2mm I think). Dots placed closer together will seem to merge. This definition translates to a person with 20/20 vision viewing, a 10” print, at a comfortable reading distance of say 12” can distinguish 286 dots per inch. From this derives the 300 dpi resolution with which we are so familiar when printing.

Now lets make a larger print,

if the print is now 20” long the eye can not take it all in at 12”; the comfortable viewing distance increases with print size and so mathematically the required number of dots per inch reduces. At 24 inches the required dpi is 144 but a full frame DSLR camera, be it Canon, Nikon or Leica, produces an image file that can be printed 36” wide at 144 dpi.

Follow this to it’s logical conclusion which is, that a sharp, well-exposed photo from full frame camera can be printed as large as you want or can afford and if you don’t believe this go up to a large poster on a wall and check out the dots; get close enough and you cannot see the picture just the dots, walk back across the street and you can see the picture but the dots are no longer distinguishable. The poster may well have been taken on a larger format camera and hold extra detail and sharpness but this is no different to the extra resolution a 6×6 transparency gives over a 35 mm slide. If you ever shot on a medium format camera you will know what I mean; those slides were to die for.

Anyway next time you have a really good shot have it printed 20 x 16 (that’s feet of course) and paste it on the front of the building across the street so you can enjoy it every day from your front window.

I have on my office wall a 20 x 30″ acrylic print from 3/4 of a frame from my M9, this was printed by Whitewall (check them out – superb prints) and the largest dimensions they would print from this file of 3918 x 2607 pixels is 70″ x 46″

In addition you can always up-size the file and if that’s the way you decide to go buy Perfect Resize, it’s wonderful!

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