Images look grainy

[ShockTop]

After watching many tutorials on Youtube and seeing a few of my friends using Photoshop I have finally realized that something is not quite right with mine. Whenever I zoom in to work on small details my image becomes rather grainy and the detail deminishes substantially. I'm not sure if this is normal or not, any feed back will be awesome. Thanks! These two pictures I are at 100% and then 740%
I'm not sure if they will appear the same when I screenshot them as how they appear on my screen.

 

[Hoogle]

All depends on the resolution of the picture your zooming in on.

If it is already a low resolution compressed image then your zoom details will get worse quicker even from 105%

If you are zooming in on an uncompressed 20 MP image then you can zoom in to 300% and not really notice any detail lost and are more likely to be able to zoom in to 500% and more,

 

[MikeMc]

Are these jpeg from the camera or were they taken in RAW ?

 

[ibclare]

Yep, looks like low resolution photo to me.

 

[peta62]

It is not grainy, these are sharp pixels. For grainy push ISO to max and compare the result.