Is it wrong to use photos [or other samples] to learn drawing?

why would it be wrong. most art is based of samples. looking at landscape and painting it is the same thing. or a building or the ocean etc etc. its not like your tracing it. if its the copyright laws your worried about then if their your pictures you took it doesn't matter. in fact if you drew something your friend took a picture of they could not sue since its your own rendition.