ronjay Loc: york Pa.

After looking at the properties /details of the exact shot Nikon is 300 dpi while the Canon is 72 dpi. When printing a 8x11 both have the same image quality. Why the different DPI number ??? This occurs also on the Canon D70 and T3i (72) dpi

GoofyNewfie Loc: Kansas City

Because PPI doesn’t matter in this case...most cases, actually.
(And it’s PPI- Pixel Per Inch, not DPI -dots per inch)
What matters in this case is the pixel dimensions.

lamiaceae Loc: San Luis Obispo County, CA

Digital resolution is in ppi (pixels per inch) for sensors and monitors. Printer resolution is dpi (dots per inch). They are not the same but they do get used interchangeably (actually incorrectly). And optical resolution (lpi) is lines per inch for lenses or film.

Both your cameras are correct and both should have the same resolution, standard is 300 ppi (though Adobe products may say dpi (incorrectly)). Both are probably 14-bit from the cameras. They are copied to your HDD by ACR or some other loading app. to either 8-bit JPG or 8-bit or 16-bit PSD, TIF or some other working file format. The difference is it seems your Nikon is displayed as say a 8"x12" 300ppi image (like my Pentax Cameras), and your Canon as 33.33"x50.00" 72ppi images (or something like that). They both contain the same number of pixels and same amount of data if the cameras have the same "resolution" in MPs. You can probably change either the 300 or 72 for either camera (for many others the default is 92 dpi) in the software somewhere. But it really does not matter. As was pointed out by others the linear dimensions are what is important, in pixels.

MichaelH Loc: NorCal via Lansing, MI

Here is a link to a DPReview post on this topic and explains it well. DPI in this case is an EXIF tag like the tag that shows what camera and lens was used to take the picture. And as others have said - it is meaningless until you are printing and then it can be changed.
https://www.dpreview.com/forums/post/29164590

Fotoartist Loc: Detroit, Michigan

Height + width + resolution (in ppi) = total pixel dimensions (file size). This is an equation. If you change one factor the others compensate and the file size remains the same.

rehess Loc: South Bend, Indiana, USA

Huh?

Height * Width = total pixel dimensions

Height * Width * Resolution = total physical dimensions if anyone actually pays attention to Resolution

Fotoartist Loc: Detroit, Michigan

Go check my post. That's exactly what I said.

rehess Loc: South Bend, Indiana, USA

No, you said


You have plus signs instead of multiplication

You say that resolution is included in calculation of total pixel dimensions

Fotoartist Loc: Detroit, Michigan

I see now. I was just trying to state the simple concept that this plus this, plus this equals that. I can see the confusion. I shouldn't use + and = signs when speaking colloquially about an equation. You are right. Makes sense. Thanks. What I was trying to say is an important concept though. It needs to be said without confusion.