Weatherizing a Raspberry Pi Camera with a Microscope slide

Sticking a Raspberry Pi camera exposed to the elements doesn’t do it any good over time, resulting in the hazy crazed lens problem.

Flare on the camera lens after a year in the open

The solution is to put some glass in front of the lens – and indeed this is exactly what this commercial outdoor spec little lipstick CCTV camera does

it's hard to see, but there is a round glass against an O ring in gront of the camera lens on this weatherpoof camera, which has spent several years outside and still works well — it’s hard to see, but there is a round glass against an O ring in gront of the camera lens on this weatherproof camera, which has spent several years outside and still works well

I discovered this when I took it apart to unscrew the lens a bit to make a close focus. And then cracked the glass refitting it as the lens stuck out too much. If you ever need a flat round piece of glass, search for watch crystal on ebay and they are to be had in lots of diameters. A watch crystal is apparently a term for the glass on a watch as well as the 32,768 Hz timing quartz crystal. A flat watch crystal repaired this camera.

The direct exposure of the camera lens to the elements is the biggest weakness of the now-defunct PICE weatherproof Pi case. But it is easily rectified now, using a piece of flat glass fitted with Sugru or Milliput putty. I used sugru and a cut down microscope slide, since I didn’t want to buy another watch crystal when microscope slides are optically flat and cheaper. It is a lot easier to cut glass under water, and you can remove the viciously sharp edges using a cheap diamond sharpening stone to smooth the cut edge and chamfer the corner.

Microscope slide fitted with Sugru to shed the water and seal the camera from the elements

I smoothed the Sugru using some plastic plumbing fitting, hence the embossed text that I didn’t spot. Hopefully this saves me from the crazed lens problem – this is a time-lapse camera to see how many weed seeds spring from my compost.

Raspberry Pi image of compost and control

The Pi does time-lapse photography easy as falling off a log – basically in crontab

# For more information see the manual pages of crontab(5) and cron(8)
#
# m h  dom mon dow   command
30 13 * * * /home/pi/takestill.sh >> /home/pi/crontest.txt

and takestill.sh is

#!/bin/bash
/usr/bin/raspistill -o /home/pi/image-`date +%g%m%d-%H%M`.jpg

the aim of all that garbage after date is to make the filename carry the date, in a way that will rank properly in a file listing, like

image-150717-1330.jpg

For some reason this wouldn’t work calling /usr/bin/raspistill directly from cron

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