rich_wardwell Posted December 31, 2003 Share Posted December 31, 2003 My brother came to visit this week and brought a very nice Meade LX200 10", 2500mm reflector telescope. After a number of trials and tribulations resulting in a whole slew of fairly mediocre pictures (vast learning experience), a repeated problem "exposed" itself with my new Digital Rebel. In long exposures over 2-3 minutes or so, a red patch begins to appear in the bottom left corner of the frame. As the length of exposure increases, so does the size and intensity of the red patch. I confirmed that this wasn't an artifact of the telescope by doing some longer exposures using the kit lens and a 50mm lense. This isn't normal is it? Link to comment Share on other sites More sharing options...
jon_stelly Posted December 31, 2003 Share Posted December 31, 2003 No, you've probably got some bad wiring or something near the sensor that's causing that portion to heat-up. I'd call Canon's tech-support and they'll probably have you mail it to them for service. Link to comment Share on other sites More sharing options...
jim_larson1 Posted December 31, 2003 Share Posted December 31, 2003 <b>But</b> long exposures on the 10D and 300D are problematic anyway because of "hot pixels". <p>In any event, a "hot zone" sounds like a warrenty problem. Link to comment Share on other sites More sharing options...
maureen_m Posted December 31, 2003 Share Posted December 31, 2003 You might want to call Canon (1-800-OK-CANON) and ask about warranty service, though "hot pixel" issues in other threads indicate that all they will do is remap the affected area with the camera's software to fill it in with the surrounding pixels' data.<p>If the hot pixels only show up in long exposures, they might not even acknowledge it as a warranty "problem" (that's my cynical side showing through my cold again). Of course, then you can ask why the camera features a "B" setting in the first place! Link to comment Share on other sites More sharing options...
charlie_vigue Posted December 31, 2003 Share Posted December 31, 2003 Try shorter exposures and stacking them. This guy uses a 10D. http://members.tripod.com/~ghonis/ Link to comment Share on other sites More sharing options...
josh_grant Posted December 31, 2003 Share Posted December 31, 2003 This doesn't really help with your problem, but I'd love to know what kind of setup you are using for astrophotography as that is something I would really, really like to start experimenting with. Any links/advice or comments are welcome. Link to comment Share on other sites More sharing options...
charlie_vigue Posted December 31, 2003 Share Posted December 31, 2003 Try this: www.meade.com Telescope and a T adaptor Link to comment Share on other sites More sharing options...
jeff_rothstein Posted January 1, 2004 Share Posted January 1, 2004 Josh, visit the websites for Sky & Telescope and Astronomy magazines, www.skyandtelescope.com and www.astronomy.com, respectively. You'll find many resources for a beginning astrophotographer. Regards and happy new year! Jeff Link to comment Share on other sites More sharing options...
rich_wardwell Posted January 1, 2004 Author Share Posted January 1, 2004 Thanks for the responses.... If it is a "hot patch", it's a big one. I start to notice the patch after about a 1 minute exposure. I've attached a 5 minute exposure with the lens cover on. I think I'll be calling Canon...<div></div> Link to comment Share on other sites More sharing options...
rich_wardwell Posted January 1, 2004 Author Share Posted January 1, 2004 Actually, that image is a 720 sec (12 min) exposure. I've noticed that it was much worse out in the 20F temperatures outside. This may have also been related to aperture although I doubt it. Link to comment Share on other sites More sharing options...
charlie_vigue Posted January 1, 2004 Share Posted January 1, 2004 12 minutes is pretty long. I'e only gone to 5 minutes on my 10D, and things are still good, but there is a start of some 'freckles' about that time. Maybe I'll try 10-15 minutes later today. Link to comment Share on other sites More sharing options...
mike sisk Posted January 1, 2004 Share Posted January 1, 2004 Although it may not apply to the problem with your Rebel (different circuitry, perhaps), here's a 778-second shot from my 10D at ISO 400:<div></div> Link to comment Share on other sites More sharing options...
rich_wardwell Posted January 1, 2004 Author Share Posted January 1, 2004 Yeah, it definitely appears that the large red-patch in the corner is NOT supposed to be there :) I can start seeing it after just a little bit over a 1 minute exposure. Canon support is off today for the New Years, so tomorrow it is. While it has already been answered by others, but for the person that asked - I particularly used a T-mount for a Canon EOS camera and a Meade T-Adapter which connects to the rear cell of the telescope )and to the T-Mount, and hence the camera). Lots of fun! Thanks for the responses! Link to comment Share on other sites More sharing options...
chris_dawson Posted January 3, 2004 Share Posted January 3, 2004 I have also experienced these "hot patches" with my 1D. With a 25 second exposure, the areas are quite pronounced, but are they because of the light reflecting off of some part of the lens. I was using a tamron 28-200 at f/11.<div></div> Link to comment Share on other sites More sharing options...
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