Photo Resolution

[m_lpz]

Hello,



My question is regarding the resolution of the pictures. With my Digital Rebel set on maximum quality I used to get 180ppi (show by the image size specifications in Photoshop) with my new 20D set on jepg format I’m getting 72ppi.

I know the 20D it’s a better camera than the Digital Rebel, but I don’t understand why I get only 72ppi. In Graphic Arts the quantity of points per inch is very important for the quality of the printed final product, but I’m not sure how that works on photography.

I’ll really appreciate if you can explain me how the resolution works and what’s exactly the difference between 5, 6, 8 MegaPixels (do you get more points per inch? bigger picture size? or what???)

Thanks a lot!

[tim]

http://photography-on-the.net/forum/showthread.php?t=62098
http://photography-on-the.net/forum/showthread.php?t=60338

[japangirl]

Hello!

I have the digital Rebel its a 6.1 megapixel. I always shoot at best quality and I get 8x10's at 300 dpi wich is very good. My advice to you is always shoot best quality you never know when you'll want to print it or crop.


see ya!
:lol:

[CyberDyneSystems]

And welcome to the Forum Japangirl and m-lpz :)

[jobber73]

The 20D takes 8 megapixel photos. They are 3504 x 2336 pixels.

PPI or DPI is only relevant to the output size.

At 72dpi that 8 megapixel image is slightly larger than 32x48 inches.

Go into photoshop and change the resolution without resampling the image. No matter the resolution the file remains 3504 x 2336 pixels (or 8 megapixels) - all that changes is the output size. For example:

At 150dpi the output image would be just shy of 16x24.
At 300 dpi the output image would be a little larger than 11.5x7.5 inches.

Does that make sense?

Essentially ppi or dpi only affects output size.