Printing to canvas

[Alter_Ego]

Hey everyone,
I'm just wondering I've been shooting all my photos on raw with a 21mp camera.
I want to get them printed on canvas but most of them are only 12-13" x 18-20" but i need them to print on 18 x 24 or 24 x 36.
Is there a way i can stretch them without losing too much quality?

 

[KmH]

You don't have to stretch them at all.

You should however be mindful of that your 5D MKIII makes images that have a 3:2 aspect ratio.

You will have to crop your 3:2 images to make a 18x24, but not a 24x36 - because 24x36 is 3:2.

Don't forget to allow for the canvas wrap dimensions specified by whoever does the printing, but after you crop to the aspect ratio of the print let the service bureau handle the sizing using their RIP software.
The Digital Print: Preparing Images in Lightroom and Photoshop for Printing

As it is, canvas has so much texture that it's pretty hard to lose to much quality.
Wonder about what kind of inks they use. Dyes need to be over-coated and don't last as long as pigments, which don't need to be over-coated.
Not all canvas printing places actually use canvas. The cheap ones often use textured plastic.

The 22.3 MP 5D MKIII makes image that have pixel dimensions of 5760 x 3840 pixels.
5760 px / 36 inches = 160 pixels per inch which is sufficient for a canvas print.

 

[Alter_Ego]

Thanks for clearing that up for me
Really appreciate it!

 

[Big Mike]

You have one of the best, high resolution DSLR cameras available. You could produce very large prints.

Keep in mind that only a few years ago, most DSLR cameras were only 6-8MP....and photographers were selling 16x20 (or larger) prints for people to hang in their homes (and thousands of other uses).

Part of the equation that you have to keep in mind, is that the larger the print, the further away you're supposed to view it from. You could create a billboard sized image from an 8MP camera...it would look terrible from 2 feet away, but it looks fine from 50 feet.

Here is the canvas gallery wrap that I have on my wall at home. It's 50" x 30" with a 2" wrap. So the printed image was just over 54" x 34". The photo was taken with an 8MP camera.

 

[KmH]

As a guideline, the viewing distance will be 1.5x to 2x the diagonal of a print.
To calculate the diagonal of a print - a[SUP]2[/SUP] + b[SUP]2[/SUP] = c[SUP]2[/SUP], take the square root of c[SUP]2[/SUP], times 1.5 or 2.
So a 20 x 30 would have a diagonal of 36 inches and the viewing distance would be 4.5 feet to 6 feet.