Photoshopstar
http://www.photoshopstar.com/photo-effects/how-to-duplicate-professional-camera-filter-in-photoshop/

September 13th, 2009
How to Duplicate Professional Camera Filter in Photoshop

This article talks about duplicating professional camera filters in photoshop. The author states that photographers use several filters that are in their camera to make some effects in the photo. But, the author explains what to do when there ISN'T any professional equipment to help you. Photoshop can help in making cool effects, but first you have to duplicate the image once and select light sources. He says to change the layer mode to Screen and duplicate that layer again. Start applying a professional lighting effect

I thought this article was quite interesting, but he used photos to explain, therefore if I write a summary (like this one) it might not be as clear as looking at the article itself. The author could've been a little more specific, but that's just my opinion. I think it was quite good in all, I will use this information in the future when I become more experienced with photoshop.