Ok, so here I was working on this new effect I had in mind. I was just experimenting a bit when I found out I don't understand the layer blending in PS. After all those years!
Here's my problem: I want to work with two layers. The bottom one would be the background and the top one would be some kind of adjustment layer to draw on and then apply those drawings to the background in a blending mode of choice. I was trying this with color burn, but then I noticed that it looked different from directly drawing onto the background with a color dodge brush.
In the picture you see a simplified version of what I was trying to do. In the middle you see the brush I was using. On the left I have used the brush directly on the background layer with the blending mode set to color burn and the opacity to 70%. On the right I painted on a new layer with the brush set to normal and 100% opacity. After that I changed the blending mode of the top layer to color burn and set the opacity to 70%.
Now, in my mind both sides should look the same. But, as you can see, they don't... :(
Can anyone please explain to me what's going on here??