Lumenera company produces very interesting quality cameras. I had possibility to test Lu075M camera.

1, Making the camera housing
2, Daylight picture quality tests
3, Frame rate and capturing speed tests
4, Simple Deepsky test

1, Making the camera housing

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:

It was really funny to make a cardboard body for almost $1000 camera :-)
Anyway it met my requirements and it produced high quality picture.

2, Daylight picture quality tests

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!

Raw frame

Stack result - 44 frames stacked, no other processing

Processed stack result - 44 frames stacked, gamma 1.30, unsharp mask 1,0,400 (processed in K3CCDTools). I have never been able to produce such image quality with webcam!

Raw frame

Stack result - 44 frames stacked, no other processing

Processed stack result - 44 frames stacked, gamma 1.30, unsharp mask 1,0,250 (processed in K3CCDTools). Remark: The DVD player was not perpendicular to the optical axis, that's why it was not possible to have focused its whole body.

I am very curious about tests with telescope when my adapter (C-mount to 1.25" barrel) arrives.

3, Frame rate and capturing speed tests

Lumenera cameras use USB 2.0 interface and provide high quality uncompressed streaming video with high frame rate.
I did several tests with K3CCDTools 3.1.4 which supports Lumenera cameras. I tested K3CCDTools 3 on 2 computers:

• Desktop Pentium 3.0GHz, 1GB RAM, 250GB HDD Hitachi 7200rpm
• Notebook Pentium Mobile 1.86GHz, 512MB RAM, 60GB HDD 5400rpm (SpeedStep power saving was active)

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).

Conclusion

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

Note

Dropped frames in capturing process don't make AVI file size bigger - the dropped frames have virtually 0 size.

4, Simple Deepsky test

I was curious about a deepsky performance of the Lumenera camera, so I put this simple cardboard camera setup on static tripod.

The static tripod enabled me to use maximum exposure 5 seconds, otherwise star movement became visible.
I think that the result is very interesting - with regard to fact that I used objective lens with diameter 25mm:

90 x 5s exposures, 12-bit mode, gain 10.0, SLR lens (focal length 50mm, F2) Captured and processed in K3CCDTols 3 (using the Field Rotation Input Filter)

Back to AstroPhotography page

Computer generated images, real images, drawings and texts are property of the author and may not be reproduced or used without permission of author.

Last Update: 21.12.2006