Author Topic: CZR Bowen ribbon-frame cameras  (Read 1154 times)

Offline Jim

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CZR Bowen ribbon-frame cameras
« on: 08/20/2024 09:26 pm »
Who knows anything about CZR Bowen ribbon-frame cameras?

Offline edzieba

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Re: CZR Bowen ribbon-frame cameras
« Reply #1 on: 08/21/2024 11:43 am »
Attached document contains a description of the operation of ribbon-frame cameras in general, and diagrams of some example layouts (for rotating-prism and slit-shutter variants). Sort of like a Fastax but with a focus on metrology rather than image stability.

Offline edzieba

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Re: CZR Bowen ribbon-frame cameras
« Reply #2 on: 08/21/2024 12:04 pm »
Attached is E. E. Green and T. J. Obst, "Bowen ribbon-frame camera," Jour. SMPE, vol. 53, pp. 515-523, Nov. 1949. which contains development history of Bowen cameras and of the CZR-1 specifically.

Offline Jim

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Re: CZR Bowen ribbon-frame cameras
« Reply #3 on: 08/21/2024 06:04 pm »
looking for info on the setup and calibration of the camera for launches.

Offline Jim

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Re: CZR Bowen ribbon-frame cameras
« Reply #4 on: 08/21/2024 06:09 pm »
Attached is E. E. Green and T. J. Obst, "Bowen ribbon-frame camera," Jour. SMPE, vol. 53, pp. 515-523, Nov. 1949. which contains development history of Bowen cameras and of the CZR-1 specifically.

thanks

Offline Remes

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Re: CZR Bowen ribbon-frame cameras
« Reply #5 on: 08/21/2024 08:44 pm »
I'm more in computer vision, but from what I read:

- there isn't much to be calibrated in the camera in the field
- timing comes from the 60Hz power net frequency
- I assume the reticles and the 3 light dots have close to zero drift and don't need any setup (at least not in the field)
- I assume they would calibrate lenses the same way as it is done today: Film a pattern with known dimensions.
-- https://docs.opencv.org/4.x/dc/dbb/tutorial_py_calibration.html
-- that delivers camera parameters like principal point, focal length, ...
- Not sure about this 3 projected light points. If they are really low drift and constant, they can be used to calibrate the system after the campaign
- Then the distance to the target would still be required. That might have be done with external equipment or by using objects of a known size. But measuring distances is a well understood topic in the military.
- The rest is done under a custom "microscope" and doing a lot of calculations with the measured points

For the setup:
- Loading the camera is done most likely the same way like magazines of film cameras have been loaded for decades: something like a glove box. But the box is a bag and everything is opaque for uv to infrared.
- the mount needs to be set up (long axis of the image is parallel to the expected flightpath)
- with more cameras and overlapping areas they most likely placed some objects close to the cameras to align them
- use the amount of slits and the frame with the right size for the slits
« Last Edit: 08/21/2024 08:44 pm by Remes »

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