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 Post subject: Pentax K110D
PostPosted: Thu Oct 29, 2009 8:33 am 
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Joined: Mon Oct 12, 2009 6:47 pm
Posts: 1268
Location: Bolton
I bought this 6-megapixel Digital SLR in October 2007 (as it was on special offer, and compatible with my numerous existing Pentax SLR lenses and accessories), and it wasn't long before I tried astro-imaging with it (see my Comets section in our Gallery). Comet Holmes (a large bright object) was an ideal target for it, so I had some early successes :-)

I've used it with a couple of different telescopes and several camera lenses - here's a summary of my experiences:
  • It's more convenient to use than my MX5C system (which needs a PC beside the telescope);
  • Focussing was aided by taking a series of short images of a bright star, and zooming in to the image on the camera display;
  • The built-in 30-sec max exposure time is long enough when imaging through a portable telescope - you really need a fixed scope (with precise polar alignment, and auto-guiding) for much longer exposures;
  • When imaging with a camera lens (for wider-angle pictures), exposures of 2-4 mins are more useful, so I built an electronic timer to control these;
  • The charge in my Hybrio rechargeable batteries doesn't last long when the camera is imaging out in the cold, so I built a DC converter to run it off a big 12V battery;
  • After a few minutes' imaging, the heat developed within the camera causes the "elecronic noise" in the image to increase noticeably. My current solution is to use the camera's "noise reduction" (dark-frame subtraction) feature, but this means that I can only image for half the time;
  • The internal IR-blocking filter on the camera's CCD drastically reduces its sensitivity to hydrogen-alpha light.

In conclusion, this camera can certainly be used for astro-imaging, but it's not a good choice for long-duration imaging of emission nebulae: a Canon with its CCD filter removed will give much better results.

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