Focus Stacking... what is it ?
Focus stacking for macros is a method to compensate for the very shallow depth of field using multiple images, with different focus.
If I’m honest, I didn’t know about focus stacking until a few days ago. Nor did I need it until now. But now that I bought a Marco lens, the topic of focus stacking became interesting to me.
Depth of field
Especially in macro photography, the depth of field is very shallow. This is due to the long focal length and very short distance to the object. To illustrate, if you photograph a fly frontally, the eyes are sharp, but the body or wings are barely visible. To further illustrate this problem, you will find an image example below.
On the picture example you can see two photos. Both pictures were taken from the same position. Neither ISO, aperture nor focal length were changed. Only the focus was set differently. Here you can see how short or narrow the focus is in macro photography. To get the whole object in focus, you need a trick. Better said a technical help.
You photograph the object several times, depending on how large / spatial it is. My final composition was made of 10 individual images. Each of these individual images had a different focus. The important thing here is that the object does not move during the shots. At least not significantly. That the camera should be on a tripod or similar is as important as a remote release. I put my camera on a chair and used the Canon app to determine the focus and trigger.
Once you have taken all the pictures, now comes the actual stacking. For this you use a software.
Known representatives are:
- Adobe Photoshop (I used)
- Helicon Focus
- Zerene Stacker
- Combine ZP (freeware)
On the page www.drs-informatik.de or Traumflieger.de you can also find a test of all programs with strengths and weaknesses. Adobe Photoshop then actually does almost everything automatically. On the linked Youtube video by Patrik Spiesecke the approach is explained very nicely and in detail. For those of you who don’t want to watch a whole video about it, here’s what it says in a nutshell.
Photoshop imports the images as layers and aligns them according to the motif. This way all image motifs are exactly on top of each other. After that Photohop looks in all layers for the sharp areas, masks them and hides the rest. In the end, you have a composition that combines all sharp areas from all images/layers and provides an almost completely sharp image of the main subject. Slight touch-ups are still possible, of course, but my photo didn’t get any further touch-ups.