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Automated focus stacking in microscopy with Helicon Remote

A useful cross-platform software tool to enhance image quality and depth of field 

Helicon Remote is a tethering software utility designed for both Wi-Fi- and USB-connected photography, enabling remote camera control (mainly for Canon and Nikon models). The camera is placed on a motorised microscope stand and is controlled via the software from a PC, Mac, Android or iOS device. The Helicon software suite also offers convenient time-lapse capabilities, alongside focus stacking and exposure bracketing. Additionally, its Live View display features options for image rotation, horizontal and vertical mirroring and displaying grid lines and rulers in the live image.

Focus stacking is a photography technique where multiple images, each taken at different focus points, are combined to create one perfect composite image with an extended depth of field. The Helicon software suite consists of two modules: The Helicon Remote module controls the camera and the focusing rail (z-axis). After the stack has been created, it can then be processed with the Helicon Focus module. The two modules are interlinked, allowing the user to switch between them with a single click, which creates an efficient, user-friendly workflow.

The automated capture of a series of microscope images taken at different focus distances significantly enhances the overall image quality in terms of depth of field and resolution. To get a perfect single image, professionals often compile and process a hundred or more individual frames.

Helicon Remote: a brief description

Helicon Remote runs on different operating systems (PC, Mac, Android or iOS) and is designed for controlling and displaying the Live View feed of modern mirrorless system cameras and DSLRs. It supports an extensive array of camera models – a detailed compatibility list is available on the Helicon website.

This report will focus specifically on the PC and Mac platforms, as the full suite of Remote and Focus can be run on them and they are most commonly used in professional settings.

Both the camera and the motorised staged are connected to the computer with a USB cable.

Wired communication via USB facilitates minimal delay and maximum image quality when viewing the camera’s live image. A wired connection via Wi-Fi is possible, but comes at the cost of lower data transfer speeds, image quality and data security.

For routine operation, we recommend using a USB cable for the connection to the computer.

Once the camera is attached to the microscope or macroscope, the Helicon software has been installed successfully and the USB connection to the computer has been established, a large live image is displayed on the computer screen.

The right side of the screen shows the camera status and the main camera settings: exposure control, ISO settings, brightness and image quality, including resolution and file format (JPG or RAW). Below, a histogram shows the brightness distribution for the three primary colours (RGB).

Further down, there is a window for adjusting the focus points along the z-axis of the motorised stage.

Once the camera connection has been established, the next step is to configure, integrate and start up the motorised stage. The Helicon software is able to communicate directly with popular focus rails, such as those from StackShot, Trinamic or Wemacro, which typically feature a stepper motor. Important settings can be accessed in the menu.

The time interval [s] between two shots is an important input parameter, as it has a direct impact on image quality: every movement of the stepper motor along the z-axis causes minimal vibrations of the entire photographic unit. To avoid motion blur, a brief pause of a few seconds after each movement is advisable.

In our example application, we used the highly popular and efficient StackShot focusing rail.

Clicking the arrow buttons on the computer display moves the unit up or down.

<<<  or >>>   Large step size

<<  or >>       Medium step size

<  or >           Small step size

The [A] button sets the upper and the [B] button the lower focus point. The number of images in the focus range can be set in the [Shots] menu item. Typically, a number between 20 and 100 is selected.

Once the key parameters have been configured, the focus stacking sequence can be started by clicking [Start Shooting]. The individual shots are then automatically saved to a designated folder on either the PC or Mac and can be further processed in Helicon Focus with a single click.

The screenshots below outline the key settings of the software:

Brightness:

Basic settings:

Additional settings can be configured in the “Image Saving” section, for example the folder where the images will be saved after shooting and the type of file storage.

For more information about the Helicon software suite, please visit the manufacturer’s website. A demo version is also available, which can be downloaded directly from the website.