Michael Shoemaker recently wrote : >I hope no one considers this off topic, but I was hoping someone would >be able to give me some advice about my recently acquired KT&C-350BH CCD >video camera. Since you plan to use it for observing artificial earth satellites I think it can be safely said that this is not "off topic":-)). At the risk of ruffling some feathers video is THE way to track satellites :-)))) (but then Im biased!) >to do the same, but I don't fully understand the camera functions, and >the instruction manual was not very helpful. the so-called "Manuals" that come with the type of CCD cameras we can afford are normally useless. The cameras were basically designed for business surveillance purposes and when we use these cameras for tracking we are outside the realm of the "Manual". Even after using my MINTRON camera for about 16 months now I still have not found my "optimum" settings and I have several "manuals" for this camera from different sources. >First of all, I'm connecting the camera to my StarMax 90 mm EQ Orion >telescope. When I point to some stars, say, and view the video feed on >my TV set, the image of the bright stars looks very bright, but it's >almost as if they overwhelm any surrounding stars. It sounds like you are using a telescope with a narrow field of view and the brightness of your bright stars is affecting the automatic gain control (AGC) in your camera. This allows the camera to view the bright star as a "normally exposed star" and actually reduces the sensitivity of your chip so that faint stars will not be seen. This AGC comes under several names - ELC ( electronic light control), ALC (automatic light control), manual AGC etc. Ideally you should switch the AGC OFF - if you can. Secondly bright stars will always appear pretty large . The size depends on magnitude, pixel size, focal length etc and also the quality of your camera lens. I had one lens which produced such enormous images it was impossible to use the lens at full aperture. In many cases it will pay to close down one or two "stops" - eg if an f/2.8 lens then close the aperture down to f/3.5 or F/4 (or f/5.6). However since you are presumably working at the focal plane of your telescope you cannot do this very easily - perhaps cut down the size of your telescope aperture with a cardboard mask. Most probably your telescope is already working at f/5 or more (eg f/8)so there is no need to reduce your aperture. My comments about changing aperture really refers to camera lenses. Some stars will appear to have nice bright halo's - these are red stars which show up very well on our infra-red sensitive cameras - in fact you can usually see red stars that are two to three magnitudes fainter than a blue or white star. If you see a star with this halo you will usually find it is a variable star. >Does anyone know what the Auto Iris Lens connector does on the back of >this particular (or similar) camera? What about that little "CC Level" >screw in the back? The thought of having to solder cables to the back >of my brand new $200 camera scares the crap out of me... >Any advice for a novice like myself? Maybe "CCD cameras for dummies"? forget about the auto iris lens connector- this usually goes to a lens that has the ability to change its aperture under control of the AGC of the camera. Since you should not have this type of lens for astro work the circuit should be open and thus nothing to worry about. Im not familiar with the "CC" control but it could be as others have commented, ie "CONTRAST CONTROL" - Ive never seen it before as you normally set your contrast and brightness on the monitor. It MAY be what is called the GAMMA control - something similar to changing contrast.If it is then there is no harm in fiddling it but do so at your own risk in case I am wrong. Ill look up your camera on the Internet over the weekend as its not one I am familiar with and will come back to you if I find out anything useful or have anything else to add. Please fell free to contact me direct if you wish and Ill help you as much as I can. Cheers Greg PS Any relation to THE Shoemakers? ------------------------------------------------------------------------- Subscribe/Unsubscribe info, Frequently Asked Questions, SeeSat-L archive: http://www.satobs.org/seesat/seesatindex.html
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