Astrophotography - When Things Go Wrong
We have all produced some, perhaps many, bad images. The images on this web site might give the false impression that it is easy or that only very accomplished if not professional astrophotographers can produce such images. That is not true. It is true that most of us have learned many things the hard way but experience and "how to" can be shared. This page provides actual images taken by members of the club which show common errors that most of us have made and overcome. We continue to make some of these errors but modern digital photography yields immediate results and the ability to try again. These examples are provided to let you identify a problem you may be experiencing and provide some basic hints to correct or avoid the problem. Under each image we have provided the name (email contact) of a club member who is willing to mentor you on the problem and how to correct or avoid it.
Alt-Azimuth Mount Field Rotation |
Click on image for details. |
Bumped the Mount |
Excessive Thermal Noise |
Click on image for detals. |
Overheating |
After shooting several frames of M57 I switched to M27. The first image was fine but subsequent images showed an increasing red glow in the lower left quadrant. I checked for stray light sources or light leaks and found none. Finally, more by accident, I noticed my battery power was dropping fast. Upon taking the in-use battery out, it felt quite warm. Subsequent shots with a fresh battery were fine. I can only conclude the battery was going bad and got hot. Its proximity to the focal plane or other vital electronics must have caused the problem. The next night I used only the replacement battery and had no problem with any of the frames I shot. Canon Rebel T5i: The red glow in the lower left quadrant was no longer present after switching to a fully charged backup battery. Richard Edmonds |
No Filter |
No Filter Image of M-45 the Pleiades taken with a simple achromatic or doublet refractor. Though visually stunning through the same telescope, the more sensitive sensors of a DSLR will quickly reveal that a doublet lens is not fully color corrected, giving the stars a multi-color psychedelic appearance. Adding an astronomical narrow band pass filter would have minimized that problem, but not fully. This is not a problem, however, with a true apochromatic triplet or quadruplet lens refractor, and any SCT, Newtonian reflector and quality camera lenses, where very little if any residual colors around such astronomical objects is evident. Klaus Brasch |
Jupiter Incursion |
Jupiter Incursion This was a first or 'framing' shot of the Eskimo Nebula (NGC 2392). The colorful rainbow effect was produce by Jupiter, a very bright celestial object, being slightly off axis and out of the telescope's field of view. The issue was resolved by installing a dew shield on the scope to block or prevent the light from Jupiter striking the optical coatings on the forward corrector plate. Equipment" 10" Meade f/6.3 Schmidtt Cassegrain Telescope, Canon Rebel XTi (DSLR) camera. Richard Edmonds |
Out of Focus |
Focus is critical. There are various methods to focus prior to a photography session. One way is to focus before nightfall on a distant object. Another method is to focus on a bright star or other light after dark. During a long session focus may change because of a temperature change of the telescope and re-focusing may be required. |
Out of Focus - Lunar |
Bad focus may be caused by not having the lens or telescope properly focused. Because the moon is moving relatively fast a slow shutter speed may also cause a blur that looks like bad focusing. |
Over Exposed |
Use the histogram either on the camera or the software used to take the exposures. To eliminate this try to increase the exposure or ISO until the view in the histogram (shown below) shows a slight gap, it doesn't need to be very much, to the left side of the histogram. |
Under Exposed |
Under Exposure
Normal Exposure
|
Light Polluted Skies |
Light Polluted Skies Image of the Rosette Nebula taken under heavily light polluted skies. The overall yellow hew on the image is due to various light sources in and around any urban setting, even in Flagstaff where low pressure sodium street lighting is common. Although image processing can reduce such effects, a narrow band pass filter that excludes most of the offending wavelengths, would be far more effective and produce a higher contrast and better color balanced image. CheckNebulae Gallery 4in the Photo section of our website for an image of the Rosette taken with a similar telescope and an IDAS LPS-V4 narrow band pass filter. Klaus Brasch |
Target Off Center |
The target in this image is in the upper right of the frame instead of in the middle. During setup do some test images with the ISO turned up to 3200 or greater to make the target easier to see or increase the exposure time and check you target is centered. |
Astrophotography on the CAS Website
Astrophotography on the Web
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