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The DFK 72BUC02 USB2 C-mount camera from Imaging Source tested on a microscope 

After the many test reports on DSLR cameras, we were also keen to try out a USB2 camera on a microscope and review the advantages and disadvantages of this camera type in more detail based on a specific example. 

We chose the DFK 72BUC02 from Imaging Source as our test camera. It is a C-mount colour camera for industrial use and falls into the lower end of the price scale (currently around € 320.00).

The camera is very small and light (70 grams) and also very well built. The application software and drivers come with the camera as standard equipment. Overall, it offers a very good price/performance ratio in comparison with specialised microscopy cameras. 

In our tests, we mounted the DFK 72BUC02 to the camera port of the Nikon Alphaphot microscope (image on the left), using our LM RelayLens05TC and a TUST38C.  

If you want to use the USB2 camera on the microscope’s eyepiece tube, you need the LM RelayLens05T instead of the LM RelayLens05TC.

Now for the technical details: The sensor on the DFK 72BUC02 is 1/2.5" in size and has five megapixels. This is the equivalent of a 5.7 mm x 4.2 mm sensor size with a dynamic range of 8 bits per channel. The sensor’s signal-to-noise ratio is satisfactory. Power is supplied via the USB cable. The colour depth is 24 bits for all three colours (RGB), which is not optimal since for microscopy applications, the colour depth should be at least 36 bits. Current DSLR and system camera models with APS-C sensors have a sensor size of 23 mm x 15 mm. In most cases, the colour depth is 42 bits. A higher colour depth makes differences in colour and light intensity more visible, thereby generating detailed, high-contrast images and videos. 

The DFK 72BUC02 does not have a mechanical shutter. This means that the exposure time for moving objects (microorganisms, live specimens, sperms, etc.) is not brief enough, which may lead to motion blur – an undesirable effect which can only be reduced by using a flash.Camera systems with a mechanical shutter can achieve short exposure times without having to use a flash. 

At full resolution (2,592 x 1,944), the DFK 72BUC02 transmits up to six frames per second to the PC. In most cases, this frame rate is not high enough to accurately capture the image, as you are simply too slow. However, if the resolution is reduced to 1,280 x 960, for instance, up to 19 frames per second are transferred to the computer. 

The bandwidth of the USB2 interface is not sufficient to send HD images to the PC in real time. USB3 or HDMI ports can manage these requirements effortlessly. Unfortunately, the DFK 72BUC02 comes with neither of these. However, many branded microscopy cameras – which are a lot more expensive – also lack this feature.

The software provided with the camera is easy to use and has many important functions.

The zoom can be selected by clicking the mouse, 

 and the captured images and videos are easy to save.

Setting the resolution is likewise not complicated at all.

The available drivers are very extensive (Net_Library, Lab_View, Matlab, etc.) and enable integration into a variety of different systems. This is a great advantage of the DFK 72BUC02 over DSLRs, which do not offer such a wide range of options. This feature makes the camera interesting for specialised applications, such as long-term monitoring, or if a camera needs to be integrated into an existing system.

Conclusion: The DFK 72BUC02 is a handy, low-cost USB2 camera which is ideal for all applications where the image quality is of minor importance. The broad range of software integration capabilities for a variety of different systems makes this camera an interesting solution for longer-term applications, such as monitoring and observations over a period of several days or weeks. However, for use with moving objects, we can only recommend it to a limited extent. 

19.04.2013