Stacking

I've been taking photos with a 'real' camera now for a few years. And looking back I can see improvement. Can't believe the photos I kept in the beginning that I would now throw away in an instant, so I also became a lot more critical. But fact remains, I'm still learning, and despite other people sometimes liking them, I feel I should do better.

By now I know a lot of the technical aspects, but actually putting that knowledge to good use to produce stunning photographs is a whole other story.

One of those techniques I have been dabbling with the last few days is called 'focus stacking'. It's a very simple principle and can be applied in different circumstances, but it's particularly useful in macro photography.

With a macro lens, the depth of field (DOF) becomes extremely shallow if you move the lens very close to the subject. That basically means that the portion of the image that will be 'in focus' or 'sharp' is very limited.

Think of depth of field as a square piece of glass, like you would have in a window. Now imagine holding the piece of glass in front of you, like looking through the window. Now imagine slicing that piece of glass through your subject, say a flower, straight down. Only within the thickness and boundaries of the glass will the image be sharp. Everything that falls in front of the glass is out of focus and everything that falls behind it is out of focus. Only within the thickness of the glass you have focus. And with macro lenses focused close up, the piece of glass becomes very thin. That's simply a given. Even a very high aperture is not always the solution. It doesn't increase the DOF (the thickness of the glass) enough, or there's not enough light to increase the aperture.

So, you take a picture of a bug, and only a tiny part of it is in focus. You can see that in the self portrait: Only the ass of the fly is sharp, the rest is blurry.

That's where focus stacking can come to the rescue.

What you do is take successive pictures of the same subject, but with each picture you shift the focus a little bit. Then in the end you run some software that's gonna combine the different pictures into one, picking only the in focus parts from every photo you took.

There's a catch: If your subject moves in between shots, the attempt fails, so it works best with subjects that are static. Insects are not very easy in that respect.

Here's one of the first results. Not a photo I particularly like, this was just a test subject.

It consists of nine photos. The first picture is the first of the nine, the second picture is the last of the nine, and the third picture is the stacked result, where more or less the whole flower is in focus.

First of the nine...

Last of the nine...

All nine combined...
Click on the photos for the larger version...