Analogue video output (AV) versus the digital HD output (HDMI) of digital cameras (digicams)
In search of the last iota of image quality in digital microphotography!
With the new full HD flat screens in
conjunction with HDMI cameras with Live View it is now also possible
for extremely good image quality to reach the monitoring screen. The
analogue video output is only a stopgap for digital systems and was
designed primarily for analogue video cameras. The digital image
information is converted to analogue format in the digital camera and
transmitted to the monitor via a 2-wire cable. Once it arrives, the
analogue signal must again be converted to a digital signal. As a
result of the conversion from digital to analogue and back again, the
image quality suffers a great deal.
The analogue standards for PAL and NTSC video transfer were devised over 40 years ago and only support resolutions up to 768 x 576 pixels with minimal colour depth.
There is no reduction in image quality with a digital transfer via HDMI from the camera to the monitor.
The HDMI output offers a considerable
advantage when using a digital camera at the microscope. A high degree
of image quality on the monitoring screen enables the user to focus the
image very precisely. In frequent cases, selecting the optimum focal
plane is not all that easy, and the focus setting is always done
manually via the microscope. Using a monitor is a quick and simple way
of optimising the image quality. However, other optimisation methods
are available: „for example, controlling the camera via PC or using the
magnifying function on the camera’s own display.
Conclusion: When buying a new camera, it should definitely come with an
HDMI output. For live presentations and discussions in particular, a
large HD monitor or projector rewards the user with excellent image
quality.
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