How can I find the source of an image?

[What]

I've been using tumblr for the past year and a half and I'm sick and tired of seeing people reposting things that I know they didn't actually make (especially when they repost MY things) and it simply goes against my principles to promote thieves, I want to reblog it from the original artist/poster or dont reblog it at all. Also, I find lots of posts that i think are really cool and sometimes I just want to ask if the artist could tell me how they did a certain technique, but I can't do that if it wasnt posted by the artist. I've tried asking reposters where they found the images without mentioning that theyve stolen someone's artowork, you know so its not hostile or anything. still, no answer. they either dont post my ask/message me back or they just avoid telling me. SO my question is, how can i find the original source of an image? The very first time the image was posted online (assuming it wasnt deleted or lost in any way since then, of course)? Please don't tell me to use google image search, it doesnt work as well as everyone says it does. Unless that's the ONLY way and otherwise impossible to source an image, I really dont want to hear it...

[Sam]

There's no way you can onow who's the original poster of that particular image/post/video UNLESS you go through the notes and patiently load through the past notes until you get to know who really posted it.

[Christa Lenz]

http://saucenao.com
also use google, go to images and upload/click and drag the image whose source you want to find