Determining Print Size ?

[billsh]

I am very new to the digital world, so forgive this very basic question. I am looking at images on screen trying to decided how big of a print I could make from this image and still have adequate detail, dof, sharpness, etc. When I view the image size in PS it indicates its approximately 48 X 32 inches. This I would assume is the image viewed at 100%. If I view the image at 50% and it looks good, can I assume I could make a print at 24 X 16? If it only looks good at 25% can I assume the print should be 12 X 8? This seems logical to me, but one man's logic is anothers folly.

I appreciate any help you can give me on this matter.

PS. I don't have access to nor am I inclined to print my own at this time. I intend on sending them out to a digital lab. I could just experiment by having some printed, but that would be rather costly I think.

[HJMinard]

You can't really make any assumptions based on what you see on a computer screen. Recommendations vary, but most print services can direct you to a chart or other information that provides a minimum recommended resolution for each print size. I've used Shutterfly on occasion, and their recommendations can be found on this (http://www.shutterfly.com/help/images.jsp#res) page. Most services have similar information.

Another way to get an idea is by changing the "pixels per inch" (PPI) of your image to a print quality PPI and then checking the resultant dimensions. Unfortunately there are also varying opinions on a minimum print quality PPI - I've seen anywhere from 180 to 300 plus. It may take a little trial and error (with actual prints) to see what level of quality looks good to your eyes.

[fdi]

Pixel resolution is not the only factor. A high quality (400 ISO or lower)3-Megapixal from the D30 is considered to be as good as film up to 11x14. A 3-Megapixal from a point & shoot may not look good at 8x10. A high quality 6-megapixal is considered as good as film up to 13x19. Other factors come into play such as sharpening and the algorithm used to res the image up before printing. I use Qimage and have been thrilled with 13x19 pics from D30 or significantly cropped images from my D60.

Mark Rogers
http://www.framedestination.com
http://www.pbase.com/lila161

[billsh]

Thanks guys. What I am understanding is since the resolution of the monitor and printing are not the same, you can't depend on what you see. I am using an 8 mp 20D and have been told I could expect to print 11X14 and 14X20 prints. I guess over time I will get a feel for what pictures I can push above 8X10 and 11X14. Sounds like being able to make your own prints is a big advantage.

Thanks again for your info.

[robertwgross]

I am using an 8 mp 20D and have been told I could expect to print 11X14 and 14X20 prints.

Yes, there should be no problem with that as long as you are shooting a maximum resolution image (RAW or JPEG or combined).

As a general rule, Canon cameras will stick an odd number in the file for DPI, and it doesn't mean much. When you get that into an image editor program, you can change it to whatever you choose. Note that for a given size in pixels x pixels, you will either fool with the DPI number or else the dimensions number to get what you what.

The goal for a print size of about 8x10 inches is to have 300 DPI for the print. The goal for a big poster size (20x30 inches) is less, maybe 180 or 200 DPI (because it will be viewed from a greater distance).

With my 6 MP camera, 11x17 prints come out nicely.

---Bob Gross---

[Hellashot]

To the poster: your dpi settings are probably set way low. Set them to 300 dpi. It will make a large size image from a Drebel/10D/20D print to 10.2x6.8 in. And I don't like to distort the image to bigger than what it says the image size is. Anytime you go bigger you lose quality.