CMOS Video Camera
by Jean-Marie Cavanihac, France
|Results : I have taken different sorts of images to test resolution and color rendering. Note that chromatic aberrations now become visible in these color pictures!|
|Marine petritrichs. (They behave like vorticella but all individuals retract at the same time). x15 objective.|
|Image of Pinnularia diatom taken with a x40 objective, showing details of the frustule.||
|The image left below was taken with a x15 objective of onion leave stomata (eosin stained): note pseudo 3D effect. The right hand image with a x40 (dry) of a Coscinodiscus diatom clearly shows the pores (around 1 µm diameter) in the frustule. In dark field, lighting is too low to obtain good contrast (but can be probably improved with a lower diameter patch stop; the one I have used is adapted for a built in illuminator in my M20).|
|Dynamic images show the metabolic movements
of marine euglena (real time) and spirulines. Here the
colors are also realistic. (See video clip).
If you use an infra red LED instead of white LED you obtain black and white pictures.
In conclusion: Perhaps a 450 lines camera would provide images with increased resolution, but its price increases more quickly than resolution, reaching 600$ or more. It's nice for me to take pictures showing the true colors of diatoms allowing to me show the colour of chlorophyl and xanthophyl! Some ideas for further experiments: Use frosted glass to better distribute the LED light, use a lens on the LED and move it away from the condenser, try polarized ligthing and improve dark field ...
All the pictures in this article, even non microscopic views, have been taken with the CMOS camera.
Below : Gallery of various images in true colors:
Comments to the author Jean-Marie Cavanihac are welcomed.
All photographs © Jean-Marie Cavanihac 2001
Published in the January 2001 edition of Micscape Magazine.
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