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Equipment Discussions >> Video and Electronically Assisted Astronomy

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Ira
Carpal Tunnel
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Reged: 08/22/10

Loc: Mitzpe Ramon, Israel
The $25 Raspberry Pi new
      #5665587 - 02/06/13 04:14 PM

Ok, video hackers. Let your imaginations run riot. What can you do with this thing?

http://venturebeat.com/2013/02/06/raspberry-pi-camera-module/

/Ira


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ccs_hello
Postmaster
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Reged: 07/03/04

Re: The $25 Raspberry Pi new [Re: Ira]
      #5665852 - 02/06/13 07:03 PM

It uses OmniVision OV5647 type-1/4" 5M pxl CMOS imager.
The pixel pitch is so small 1.4um*1.4um thus BSI type is selected.
It can do 5M still or various format of continuous (motion picture) read-out.

http://www.ovt.com/download_document.php?type=sensor&sensorid=66

I would not recommend using it for astro application except for very bright objects, i.e., solar system imaging.

P.S. IMHO, not a good fit for this astro video forum.

Clear Skies!

ccs_hello


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mattflastro
Vendor - Astrovideo Systems


Reged: 07/31/09

Loc: Brevard County , FL
Re: The $25 Raspberry Pi new [Re: ccs_hello]
      #5666103 - 02/06/13 09:57 PM

The old Meade LPI has a sensitivity of 3v/luxsec . This one only 0.7v/luxsec . So bad even for solar system.

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Ira
Carpal Tunnel
*****

Reged: 08/22/10

Loc: Mitzpe Ramon, Israel
Re: The $25 Raspberry Pi [Re: mattflastro]
      #5667723 - 02/07/13 07:36 PM

Too bad. So sad.

/Ira


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Larry F
Carpal Tunnel
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Reged: 05/24/04

Loc: Westchester, NY
Re: The $25 Raspberry Pi new [Re: Ira]
      #5668409 - 02/08/13 07:26 AM

Even if you set it up for solar imaging, it records in H.264 which Registax doesn't like, so you'd have to convert the file, which is a pain.

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ccs_hello
Postmaster
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Reged: 07/03/04

Re: The $25 Raspberry Pi new [Re: Larry F]
      #5668461 - 02/08/13 08:23 AM

That module does not pump out compressed video. The compression is done by the software within Raspberry-Pi itself.

Clear Skies!

ccs_hello


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benula
super member
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Reged: 04/27/11

Loc: Stillwater, MN
Re: The $25 Raspberry Pi new [Re: ccs_hello]
      #5961886 - 07/09/13 09:34 AM

The sensor supports 2x2 binning. Could that make it a little more usable?

-Ben


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ccs_hello
Postmaster
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Reged: 07/03/04

Re: The $25 Raspberry Pi new [Re: benula]
      #5963039 - 07/09/13 09:40 PM

I am going back to the device datasheet and here is what I found:

- OV5647 is not using the parallel bus (DVP mode) to send digital video to Rasp Pi's main ARM CPU but instead using the high-speed serial bus (MIPI's CSI-2 interface) to send to Rasp Pi's integrated SoC GPU Broadcom VideoCore IV (same package as in the CPU ARM11 core). Omnivision image system chip requires a NDA to get the full spec.

- Rasp Pi's GPU receives the digital video then compress down to H.264 in video mode
The firmware is close-sourced.

- OV5647's DPC module seems to be only doing Defect Pixel Correction, as opposed to similar chip OV5642's image processing module (can perform simple compression as well)

- OV5647 can do 2x2 binning on the like-color pixels. Binning, oddly, is stated as voltage averaging (not using the term "summing") which happens before A/D conversion. It does not state it is summing in charge domain but already in Q -> V converted voltage values in voltage level. As a purist, charge-domain summing is better.

- However, in RaspPi wiki of the camera module, the functions of: windowed capture, binning mode, etc. are not exposed to be user controllable.

My view, I wouldn't spend time further on it.
There are more exciting image systems out there.

Clear Skies!

ccs_hello


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