|"When I consider your heavens, the work of your fingers, the moon and the stars which You have set in place, what is Man that You are mindful of him?" -- Psalm 8:3,4|
Lumenera camera support into K3CCDTools
Lumenera company produces very interesting quality cameras. I had possibility to test Lu075M camera.
Camera has C-mount thread which enables to attach it
to lens or to telescope (by means of C-mount to 1.25"
barrel adapter). As I didn't have any adapter for lens or
telescope, I decided to construct a cardboard body for my
50mm SLR lens and camera until adapter arrives:
And here are my first testing picture. Light was very dim (shielded 11W neon light, the objects were in shadow on the oposite side of living room), but camera has good sensitivity. All frames were taken with 50mm F2 lens, exposure 133.5ms, gain 5.7. Camera produces high quality picture - USB2 delivers non compressed picture. Picture scan is progressive, so you cannot see any interlacing artifacts. I was very surprised with sharpness of image (remember - the optics was attached only to cardboard body and focusing was quite difficult because of not solid body!). When gain is set to 1.75 (default value), then its noise is not noticable - the produced streaming video looks like still picture!
I am very curious about tests with telescope when my adapter (C-mount to 1.25" barrel) arrives.
Lumenera cameras use USB 2.0 interface
and provide high quality uncompressed streaming video
with high frame rate.
I tested the speed of capturing in both stream mode and long exposure mode. I also tested how the speed is affected by using the Brightness Level Meter (I used the most demanding mode for computing power - Show Numbers, Show Histogram, Show History). I always captured a sequence longer than 2GBytes (120s - 180s capturing time). The frame size was always 640x480, the exposure time was always 15ms.
Here are the results of various tests:
Note: The first part of tests was done with K3CCDTools 3.1.4 which enabled 16-bit capture mode. Later, the 16-bit capture mode was replaced by the new 12-bit capture mode in new K3CCDTools 3.2.5 version (16-bit mode is still available via ini file settings if required - look here). 12-bit capture mode is faster and it captures the same amount of information, because Lumenera cameras capture frames internally in12-bit mode (i.e. in 16-bit frames mode only the higher 12 bits contain valid data).
If you want to achieve the highest frame rate, use the stream capture mode. If you have a slower processor, then switching the Brightness Level Meter off will help. Also you can try to set the less computing power demanding Level Meter mode - e.g. only levels, without history. In modern computers usually the bottleneck is a HDD. E.g. in 640x480 @ 60fps, 8-bit monochrome mode it requires the following speed:
HDD speed (08bit) = 640 * 480 * 60 B/s = 18432000 B/s
For 16-bit mode it is:
HDD speed (16bit) = 640 * 480 * 2 * 60 B/s = 36864000 B/s
For new 12-bit mode it is:
HDD speed (12bit) = 640 * 480 * 1.5 * 60 B/s = 27648000 B/s
Dropped frames in capturing process don't make AVI file size bigger - the dropped frames have virtually 0 size.
The static tripod enabled me to use maximum exposure 5
seconds, otherwise star movement became visible.
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Last Update: 21.12.2006