Optimum DPI for Prints

[WorldCountries]

I read on one picture book publisher website that they want 300 dpi images for printing, but I see that on my Smugmug "Buy this Photo" interface that the Smugmug printers will take a 3504 x 2336 pixel image (30d image) and print ship a print up to 36' x 24", which works out to be about 97 dpi if dots per inch equates to pixels per inch, which I'm not sure about either.

What is the largest print you would want to make from that size jpeg?

[Jonathan H]

It's primarily dependent on the printer. As you correctly stated, most printers' ideal input resolutions are right around 300 ppi (more is not necessarily better). Note that I said "ppi" and not "dpi" -- PPI = pixels per inch. DPI is an output resolution - how many dots the printer will lay on the piece of paper in a given inch.

It's mostly semantics, but can help to clarify the thought process. An image, from a 30D (for instance) shot in RAW has pixel dimensions of 3456 x 2298 pixels. This means, that at 300 PPI, you would expect the native 100% output to be 11.52 in x 7.66 in. To increase your output size at 300 DPI, you would need to interpolate the image and "create" pixels that don't actually exist. Of course, the need to interpolate is dependent entirely on the output medium. Printing on canvas, for instance, that same file which allegedly has a max size of 11.52" x 7.66" would almost certainly look wonderful on a 36" x 48" canvas, as long as the printer operater is skilled.

So the short answer to your question is... there is no answer... you could ostensibly print a 20 foot billboard off that same file. There are too many variables to accurately answer your question.

Hope this gave you a little more insight into the printing process. Feel free to ask for clarification.

[wlescall]

Jonathan types faster than me. :oops:

[WorldCountries]

Actually, I believe it does, thank you very much. It tells me that the 30d images are going to have more than enough resolution, which means anything shot with the new 5d will be definitely in the ballpark for about anything I want to do with them. Is shooting RAW absolutely mandatory for good printing?

[newbie_photog]

I know a few pros im my area shoot only in JPG mostly large fine but one claimed to have made a 20x30 print from a small JPG. If you are going to shoot them you just have to make sure your exposure is spot on, I shoot Raw for safetys sake.

[PhotographerS]

I know that when I shoot for several large puclications, I will use a Large RAW File with my 400D. I shoot with this RAW file so I can return to the image during post processing and correct the White Balance, Exposure, etc, etc...... (all hour or more per photo.. I know, I kmow).
And I so far (Knock on wood) have had any problems printing out my images (using a pro printing comapny) up to the poster size of 20" x 30". ( I have one image that I would love to make larger but It starts costing to much $$$$$$ any larger than a 20" x 30") :-(
And also (yes i know bad grammer starting with the 'and') how ever when I am shooting photos for the school yb and the newspaper we try and get our images above 300dpi and i have used a large RAW file (converted to JPG w/ no upsizing and no croping) to cover a spread. And it turned out fine. -Ill try and post a copy if I can find it- :-)
TGIF