What is the largest size print I can produce from 5D Mark III?

[tdehan]

I shoot only in raw and work on my images in LIghtroom 6.  I export the images typically as a .tiff and sometimes as .jpg at the largest size.  What is the largest print size I can produce?

Thanks!

[tdehan]

Been selling them for some time...

[TTMartin]

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@tdehan wrote:

Been selling them for some time...

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Given your 5D Mk III has the most megapixels of all the cameras you have listed and you've been selling 16"x20" prints for some time, why the original question?

[tdehan]

Because, in my ignorance I didn't realize that the max pixel size that is produced by the Mark III is less than the images I've been having printed.  And, I've noticed some issues on some of the prints, not all.  I was surprised to learn that the max pixel size produced by the Mark III was less than 16 x 20.  And again, probably because of my ignorance, but I display a lot of my images as my desktop background on my 30 inch monitor and they look terrific.

So, if I am to continue producing larger images (at least 16 x 20) or even larger perhaps do I need a different camera, a different process, or a different tool to enlarge (if even possible) my images?

[TTMartin]

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@tdehan wrote:

Because, in my ignorance I didn't realize that the max pixel size that is produced by the Mark III is less than the images I've been having printed.  And, I've noticed some issues on some of the prints, not all.  I was surprised to learn that the max pixel size produced by the Mark III was less than 16 x 20.  And again, probably because of my ignorance, but I display a lot of my images as my desktop background on my 30 inch monitor and they look terrific.

So, if I am to continue producing larger images (at least 16 x 20) or even larger perhaps do I need a different camera, a different process, or a different tool to enlarge (if even possible) my images?

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No you were not ignorant. People who told you 300 PPI regardless of print size are the ones who are ignorant. You have to take into account viewing distance, and visual acuity to determine, the actual PPI required. 

Someone already mentioned billboards actual only require 10-20 PPI. 

The larger the print, the greater the viewing distance to see the whole photo at once, the lower the PPI requited.

[TTMartin]

Back in 2006 New York Times technology writer David Pogue for the TV show 'It's All Geek to Me' took a photo and made 16" X 24" prints of a photo printed at 200 PPI (~13 megapixels), 150 PPI (~8 megapixels), and 100 PPI (~5 megapixels). He had the photos on display on Time Square in NYC. Of the people who stopped only 1 person in 20 could correctly identify which photo was printed at which PPI. 

That's why in my initial comment, that you're likely the only one who sees any difference.

edit: as a rule of thumb, when taking into account visual acuity and viewing distance, you don't need more than 8 - 12 megapixels after cropping, regardless of the size of the print. And that is why testing sites, will generally use those resolutions for their 'print' tests.

2nd edit: This was also why Canon was 'stuck' at 18 - 21 megapixels for all those years. There was no 'technical reason' to increase megapixels beyond that despite Canon being the first company having the technical ability to do so. It was only when market demand (due other companies marketing, not science) that Canon was forced to increase their cameras megapixels.