I just watched a brief series of videos on the "important basics" of Photoshop. It started well – Layers. Yes, layers are critically important, no argument there. Opacity. Ok, I guess opacity is important, in a way. Masking. Yes! Masking is really important, though most people don’t use it intuitively, in my opinion. (Article: The right way to use layer masks).
Number 4 – Blend Modes.
No, no, no, no, no.
I see the use of layer blend modes in post-processing very often on the beginner forums I visit. It’s sad how widely-recommended these methods are.
Blend modes are not for enhancing images. Try talking to a pro photographer, or going to the RetouchPro forum (where the real experts hang out) and mentioning blend modes. If you’re lucky, you’ll be laughed at politely, and gently pointed towards Levels and Curves tutorials. If they’re in a mood, you’ll be flamed mercilessly.
I understand why they’re popular among JSOs. They give a quick "wow!" to your photos. Without examining too closely, they appear to improve your photos. They even appear to give you control over your editing.
It’s an illusion.
Blend modes give very little control, and can’t be relied upon to improve your images under close scrutiny. A Screen layer lightens shadows, but blows out highlights. A Multiply layer darkens light areas, but it clips shadows. An Overlay/Soft Light layer creates midtone contrast, sure, but it brightens highlights and darkens shadows without control; and it does it uniformly, which is rarely desirable.
No, ditch them. Take genuine control. Read histograms, use Levels or Curves, master selections. You’ll never regret it.
If you have a question about this article, please feel free to post it in Ask Damien.