Modifying a Pentax K110D for Astrophotgraphy (2024)

My long story of modifying a Pentax DSLR for Astro or InfraRed photography will be of limited interest unless you are considering astrophotography, IR imaging, or Pentax Repair Service.

I bought a Pentax K100D DSLR in part because of the number of "K" lenses we own. I was aware was limited support for Pentax in the Astroimaging world. I love the camera, but was concerned about all the handling going from daytime photos to nighttime imaging. I was constantly blowing out dust from all the lens/telescope changes. I was also concerned about the camera’s poor response to red nebulas.

When I spotted the K110D on sale for $349 I decided to buy a second Pentax DSLR for nighttime work. I also wanted to remove the "IR Filter" found in front of most camera sensors which attenuates visible Red light at 656 nm which is emitted by many nebulas. The camera was low cost enough to dedicate to astro photography and the IR photography I would like to explore. Once the filter is removed, the images are too red to reasonably color correct. I could not find anyone who provides this modification for any camera except, "The Big two."

I tested the new camera 4 days then opened it up. It took a bit over an hour to reach the filter, which is easily removed from a K110D. I suspect the movable sensor of the K100D would be more difficult. Unfortunately once re-assembled the camera did not work. The top display would come on for a second, then the camera would go dead. I recognized the symptoms of "memory card door open" but could not find the door switch. After numerous openings of the case I realized the switch lever was broken off the circuit board so there was nothing for me to find. By then I had done too much damage to the board to continue.

I boxed up the camera and threw myself at the mercy of Pentax Service in Colorado. I shipped the camera with a note explaining what I had done, why I did it, and how I want the camera returned with the filter still off. After 3 weeks with no response I called Pentax, worked my way through the menus to a person, and asked for status. He said the quote was $211. It was more than I hoped, but to get a working Nikon or Canon modified for Astro costs even more. I said go ahead. I did not ask how long the quote was ready before I called.

All contact with Pentax was cordial. I was given a repair number so I could check status on line. I later emailed Support for a PIN number, both are needed for status checks. I got a prompt reply. Curiously the status showed quote approved but it took a week before it showed quote sent (I never got one).

It took two more weeks for the camera showed a ship date with UPS tracking number. Total time in Colorado was over six weeks. I’m glad I had the K100D to use in the meantime. When the repaired camera arrived I was concerned they may have ignored my request and put a filter on since the camera can’t be calibrated without it. I was delighted when my first photo of a neighbor’s tree looked bright red, even had the IR glow. For $349 + $211 I had a modified Pentax DSLR!

The night sky has not been clear since. The below link compares the K110D with the K100D on a night when I could not see any stars in the Southern Constellations around the nebula. The first two images are 3 frames stacked, dark subtracted, no flat, and minimum processing. The unmodified camera shows a very weak nebula and is oddly white when it should be red. The modified camera is too red but the nebula is bright. The third image is 22 frames stacked with dark, flat, and bias frames and some color correction so brighter stars look white. When the sky is clear it will look a lot better.

http://pages.cthome.net/astroleo/filterdemo.jpg

JPEG is 800 * 1800, be sure your browser shows it full size.

What is the bottom line? I’m very pleased with my modified camera. If I had it to do over I’d call Pentax first and see if I could convince them to remove the filter. It should cost less then $211 since my camera required a new board. If someone is crazy enough to try the modification themselves write me first and I’ll type up some notes. I also have a few photos of the open camera I wish I looked at sooner since one shows the switch BEFORE I broke it off.

Last edited by LeoTaylor; 05-26-2007 at 04:17 PM. Reason: Added comment about JPEG size

Modifying a Pentax K110D for Astrophotgraphy (2024)
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