K100D on the ocean floor

Started May 16, 2009 | Discussions thread
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bensheppard Forum Member • Posts: 73
K100D on the ocean floor

Hi there,

This is my first time posting in the Pentax forum. Your help/brainstorming would be greatly appreciated!

I'm an undergraduate engineer at Cambridge University. This year I've been building a vessel to take photos kilometres underwater, for under £1000 ($1500). More details can be found at:


My idea was to fill all the electronics with a non-conductive, incompressible liquid. This would prevent them from collapsing at the high pressures found underwater. However, filling a camera and lens with oil introduces many problems!

Pentax kindly supplied me with a K100D, which I have modified by removing the mirror assembly and shutter (as they didn't work properly when surrounded by oil). I have built a mirror lens that is specifically designed to be filled with oil instead of air.

Yesterday I tested the camera and lens in oil, and it worked quite well for a "home-made" lens!

However today, (after the camera has been sat in oil for 24 hours) the image quality for a near identical experimental setup has dramatically fallen.

If anyone has ideas of what could have happened I'd love to hear them. I'm supposed to be dropping it into the ocean early next week, so have very little time left to work out what has happened!

One idea I had was that yesterday the oil didn't displace the air pocket behind the blue glass in front of the sensor, but slowly seeped in overnight? (If that's the case then there's not much I can do to improve the image quality back.)

Looking forward to hearing your ideas!


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