Please explain resolution for me so I get it :)

[coffee]

All this time, and all the reading in trying to figure this out, but still can't rap my head around it.

Everything I see a tutorial on something, a resolution of 72 is used. But I was always under the impression that a res of 300 is what one should be using, and have always done so.

I was hoping that this could be explained as if you were talking to my 5 year old Daughter. hehe Including the basic explanation, I would love the following questions addressed.

1. When creating in PS, or editing an image, when should one use a res of 72? or 300? and why?
2. How does this affect printing?
3. Why is an image in 72 so much larger in physical size than 300?

I'm begging you, if I can't figure this out I might have to go postal on my cat.

[sandrac]

Oh I am subscribing to this because I would like to read the answer

[glenafton]

Joseph,
I have looked up the answer to your problem in the Photoshop CS3 book.
The number of pixels per unit length in an image is called Ïmage resolution" usually measured in pixels per inch (ppi) An image with high resolution has more pixels (and therefore a larger file )300 ppi or higher than an image of the same dimensions with a low resolution 72 ppi or 96ppi.
I hope this helps you

[Kaye]

....JUST WONDERING IF THIS THREAD BY JOSEPH WAS FORGOTTEN BY THE TUTORS??

Joseph, here is something that has intrigued me for a while:

I believe that most DSLR's take images with a res of 300ppi. My old P&S always took images with 72dpi.
Images I have taken with my D90 (300dpi) ..... If I view these in my Windows folder, let's say a landscape orientation.... then I rotate my image to portrait orientation, then look up the properties, the dpi drops to 72dpi, but if I rotate the image in Photoshop, the dpi remains at 300dpi. I am not sure why this happens. I have just learned to not touch the image until I am in Photoshop.

As far as 72dpi being larger in physical size, I have an idea in my head, but don't know how to explain it. I think I'll leave it here... too much for the brain