poster print quality

[Lize]

I want to make some poster prints of photographs, but with 300 DPI (which is recomended by most photographers and printers) it won't be much of a poster (the pictures are 10 megapixels). When printing at poster sizes, lets say 28 by 41 inch/ 70 by 105 cm, how low can the DPI get? Posters aren't going to be looked at really close, but it shouldn't look reeeeally bad up close either...

I have mailed a company that prints some nice posters of the size I want, most of them are from photographs, and they're all printed at 300 DPI (so they say)... what kind of camera's do those photographers have? they can't all have 40 MP sensors, right?

This sort of stuff gets me really confused, I would just try and print some sizes, but my budget is too limited for that. I'd love to hear from people that have experience with large prints!


UPDATE: I had some 75 x 50 cm prints made from the pics, and they turned out great

[dcclark]

Dirty little secret here: almost no poster sized photos are ever printed anywhere near 300 dpi. To print a 24x36 inch poster at 300 dpi, you would need a 77 MP camera -- ain't gonna happen! (This is assuming you use a digital camera, which -- if you're here, you probably do!)

But, you don't need 300 dpi on such a huge poster. Viewers will be standing 3, 4, or more feet away to view them, and they will be looking at the whole poster -- not trying to taste it.

A 10 MP camera can print 24x36 at 107 DPI, and that will probably look just fine. For comparison, a 24 MP camera (approximately a Nikon D3x) can print at the same size, at 166 DPI. The difference would be hard to see without a jeweler's loupe.

So the answer to your last question is: photographers shoot with whatever cameras can help them make dramatic, eye-catching, interesting photos. The photo itself will vastly overshadow details of 100 vs 200 vs 300 dpi.

BTW, my credentials: I have printed many poster-sized prints for clients. Some of them have come from my 10 MP D40x, some even came from my handy dandy 7.1 MP Sony pocketcam. I've never had a complaint.

Edit: if you want to check my numbers, here's an easy formula:

DPI = SquareRoot( MP * 1,000,000 / (w*h) )

where MP = megapixels (e.g. 10 or 12) and w*h = width times height, in inches.

[OsmosisStudios]

I've done several 20x30 and 24x36 prints from my D80 (10mp). They came out great!

The only real problem is when you start printing at about twice that size. anything less than screen resolution (approx 75DPI) will look a bit pixelated up close, but generally those sizes are seen from such distances that it really doesnt matter.

[Lize]

thanks, that makes me a bit more confident to try those poster sizes out. I'll update when they arrive!

[zarquon]

Just wanted to chime in and thank you for the information, this is something I've always wondered about. I have a photo of an old poster I wanted to get reprinted, I took it with a D80, and I wasn't sure how big I could get it.