Mike Westkamper wrote: > > You may be well aware of these issues, however I'll mention them just in > case... > > The CCD imaging of astromical objects adds some interesting problems to > imaging in general... > > Stability - You will need to grab many fields and integrate them to produce > a good image. In that time the imager must be tracking the object and be > very steady. That includes electronically. You need a good low-noise > converter and a pretty good camera. And good cabling soas to keep noise as > low as possible. There are some folks doing some real interesting work with USB cameras using Windows code. I don't have a Windows box anymore... anywhere... so I've got to look elsewhere. Long exposures appear right out unless I start revamping code, so multi-image integration is it. Tracking (mechanically) is achieved by using a 4.5-inch Newtonian reflector with computer controlled motor drive. If I have to dedicate a 2nd camera to off-axis guiding, I guess I will. > Spatial accuracy - You will need to use a pretty good lens too and to > compensate between fields in the frame. While in astro the trig says the > difference in array rows has only a small effect the interlace in most > cameras must be handled properly. Placing the CCD array at the prime focus is an acceptable alternative. If that fails, I'll sacrifice a lens to the imaging gods. What I may have to do is acquire the 3 interlaced images and use something to reassemble them. Or, come up with a mechanism to take them to three-field FITS data. > Color - Here the rendition is only important if you are interested in color. > If you are you should know the color curves for the camera and that of your > final output device. This is a complex subject by itself. While I intend to do untouched color acquisition initially, as I get more serious with this, I expect I'll use a filter wheel and acquire in monochrome, then integrate the filter-wheel images. It will be interesting to characterize the color curves for the cameras I have to play with -- all cheap USB devices, to start. > Do not compress your images anywhere along the path. In astro you are > looking for the detail. Thanks. Good point. > There are a lot of good references, and some commercial products, that will > help make it fun and useful. Most of the commercial products are 'way too expensive for me at this point. Further, few have even looked at a USB interface, and I don't have much that'll allow me to run a machine with a decent parallel port or scsi port that far. > As far as 4l or 4l2 the choice should be 4l2 only because it will offer > better reliability and control. Thanks for the tip. > Good luck... Indeed. Thanks for the info. Still looking for anyone else with ideas, too! Regards, Gerry -- Gerry Creager -- gerry@xxxxxxxxxxx Network Engineering Academy for Advanced Telecommunications and Learning Technologies Texas A&M University 979.458.4020 (Phone) -- 979.847.8578 (Fax)
