In my previous post, I explained my post processing workflow of macro photographs. In this post, I shall explain one of the important techniques in macro photography — Focus stacking.
What is Focus stacking?
Focus stacking is a technique used to extend an apparent depth of field in a shot with post production. This works especially well for macro and landscape shots. It will be more useful when the highest F stop is often insufficient to render everything in focus.
Why do you need to use Focus stacking?
When we require more depth of field (or more area in focus), we typically increase the f stop setting. Choosing a higher f stop increase the necessary exposure time, and in extreme cases it can also reduce the sharpness due to diffraction (see the table below)
If you don’t know about f numbers, read: Introduction to Aperture in digital Photography
Below are the 4 things you should do before focus stacking
1. Use Sturdy Tripod
A tripod is the supreme image control device, allowing you to compose the picture perfectly. Using a tripod is also the only convenient way of shooting multiple frames exactly the same picture at different focus area, allowing you to choose the rendition you prefer in terms of depth of field
2. Choose Manual Focus mode
Manual focus means that you are in full control. You can’t blame the camera for an out of focus shot; it is only about your skills and interpretation of a scene. Range of focus area should be chosen manually according to the size of the subject which in turn helps to stack the images perfectly.
3. Use live view mode
The Live View shooting mode available on your camera removes the element of doubts like focus area and outcome of exposure settings. It effectively turns the camera’s LCD screen into a giant viewfinder, giving you a live preview of the image. Once you activate Live View mode, the mirror is locked up, allowing light to constantly hit the sensor. It helps to predict the focus area according to the aperture you set.
4. Apply common settings
Aperture, Shutter speed and ISO play a major role in focus stacking, and it controls the details of the entire frame. Right choice of settings should be applied according the lighting. If you are stacking ten images, all the images should have the same EXIF details except focus area. Otherwise, the output will be very clumsy, and spooky colors will be show up in the photograph. Below is a typical example of how you should focus stack an image.
If we stack the images with different F-numbers, output will be like above mentioned example. So, it’s better to apply the common settings for all the images to be stacked.
To keep the entire frame in focus, number of images to be stacked vary according to different F numbers (see the table below)
Focus stacking Software
• Helicon focus(highly Recommended)
• Adobe Photoshop CS5 or above.
• Zerene Stacker
I hope you will find these tips useful. I would suggest you to follow this before focus stacking any photograph. In my next post, I am explaining focus stacking tutorial in photoshop.
More from Srivatsan Sankaran:
- 2 things you should know before post processing macro photographs
- Step by Step Photoshop tutorial on post processing a Macro Photograph
- 10 tips for shooting macro droplets on flowers