How to increase depth of field in a photo and what is focus stacking

Effective blurring of space outside the field of focus is called “bokeh”. The beautiful visual effect has become a popular photographic technique. Today such a mode is in the camera of any smartphone. But in scenarios that require as much of the space as possible to be in focus, blurring has to be dealt with. In the material we will get acquainted with one of the most effective methods of such a struggle.

What is the problem?
As we already know , focusing distance is one of the parameters that affect the depth of field (DOF). The relationship is direct: the shorter the distance to the subject, the narrower the area that comes into focus.

This often becomes a problem with product photography. If the subject of the photo shoot is small, it fits completely into the field of focus.

If the dimensions are larger, changing the diaphragm helps. Typically, for subject shooting, values ​​in the range of F / 8 – F / 16 are used.

The method has several disadvantages:
Most optical systems lose sharpness when shooting above f / 10.

The subject may not fit entirely into the field of focus, even at the maximum aperture closed. In this case, you will have to go further and crop the edges of the image in the editor. If the matrix of the camera is 24 megapixels or less, there is a possibility that the resolution will remain too low after the crop.

By adjusting the DOF with aperture, you lose an important tool for adjusting exposure .

At F / 16, little light enters the sensor. As a consequence, this setting places increased demands on the light sources.

How do we shoot?
A series of shots with different focusing distances – focus bracketing – will help to avoid problems. This is an easy way to increase the depth of field.

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But here, too, there are limitations. During shooting, the camera body must be stationary. This requires a tripod and a remote control (or any other means of remote camera control).

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In order to eliminate shaking, photographers often use an in-camera shutter release timer. With focus bracketing, this option is not convenient, since one series can have 20 frames or more. Even with a timer of a couple of seconds, the shooting will take more than a minute, which will greatly increase the labor intensity of the work.

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In order to obtain a series of images, you must:

Install a suitable aperture in the chamber. It should not be too open, otherwise there is an increased risk of out-of-focus areas. Better to use values ​​from F / 5.6.

Mount the camera on a tripod, choose a shooting plan.

In manual focus mode, aim at the end of the subject closest to the front lens.

Take a series of shots, removing focus as long as the farthest part of the subject remains in focus.Modern mirrorless cameras have software tools for manual focusing: peak focusing (focus peaking), zooming a selected area. Focus peaking highlights the peaks of sharpness with color, this helps you navigate what the lens is focusing on right now and when you can stop shooting.

Scaling will allow you to more accurately focus the first frame. Further, it will only interfere.

In some cameras (Canon EOS R, Nikon Z6, Nikon Z7, Nikon D850) the manufacturer provides the ability to shoot several frames with a focus shift. In this case, it is enough to adjust the focusing step and the number of frames, and then focus on the near edge of the object. The camera will do the rest automatically.

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The choice of the focusing step depends on the aperture: the more the aperture is open, the smaller the focusing step should be and the more frames must be taken.

What do we glue?

After the photo session, we will get several series of 5 – 15 shots, if not more. This material needs further processing. It is necessary to combine areas with different focusing distances, crop the edges and compensate for “Focus Breathing” – the change in focal length depending on the focusing distance. Let’s consider programs that simplify the process.

Adobe photoshop
Among the functions of this photocombine, there was a place for gluing series with a “walking focus”. To open multiple photos as layers, you need to use the command: “File” => “Scripts” => “Load files into stack”.

In the window that opens, clicking on the “Browse” button, select the required files (or the entire folder). For automatic alignment, check the box next to the “Attempt to auto-align source images” setting.

When exporting files from Lightroom, select the images you want and execute the command: “Edit in …” => “Open as layers in Photoshop”. Select all layers and apply the command: “Edit” => “Auto-blend layers”. In the window that opens, select “Stacked images” and check the box for “Smooth transitions of color and tone.”

After completing the process, a mask will appear next to each layer, which can be manually adjusted with a brush. White will add areas, black will remove. No intervention is usually required. Now the photo can be saved using the command: “File” => “Save As”.

The main advantage of Photoshop is its versatility. But there are also a couple of downsides:

A small number of staking options.
Long time to complete the process: depending on the number of files, their resolution and the power of the PC, the merging will take from 3 to 15-20 minutes.
Photoshop is a good option as long as you don’t have to process many series. Otherwise, you should take a closer look at specialized programs, the most popular of which is Helicon Focus.

Helicon Focus
The software has a simple interface: all the necessary elements are located on the main screen.

To work, just drag a series of photos onto the interface area or use the “File” => “Open Images” command . Importing is instant. After that, they appear on the right side of the program interface.

Now it remains to choose one of three processing methods and start the process. Each algorithm provides the user with a unique arsenal of possibilities for solving specific problems. One cannot be recommended. Let’s look at the result of all processing options.

Working with glare was better given the second algorithm. Differences in the elaboration of fine texture are negligible. And yet the results in methods “A” and “B” look a little more textured. A uniform surface was best treated by method “A”. B and C have color noise.

To select the most successful option for each situation, there is a visual table on the official website.

The advantages of the program include good optimization, efficient allocation of PC resources and, as a result, a multiple increase in the speed of merging photos. The latest versions have added the ability to work with RAW files without prior conversion.

The example shows the actual processing speed of an image stack of 19 files (PC: Ryzen 3600 + RTX3070).

Helicon Focus allows you to save the result in uncompressed Tiff or DNG – containers that leave the maximum amount of information for further editing. The size of such files with a resolution of 42 megapixels reaches 120 Mb.

Focus bracketing is a simple and effective technique that does not require expensive equipment and serious experience from the photographer. At the same time, it opens up new possibilities in subject photography.

In addition to the subject, the technique is used in macro photography and landscape photography. In these scenarios, it is more difficult to use due to the possible movement of the subject, but after a few training sessions on stationary objects, you can try something more serious.