Removing the infrared filter on the Sony CyberShot DSC-P72

This modification will make the camera suitable for infrared photography.

1. Take out batteries and leave the battery flap open. Take out the memory stick also leaving the flap open.

2. Take out the 4 external screws, one of them is in the memory stick slot.

3. Starting from the battery side, pry the two halves of the case apart. The back half has a ribbon cable attached to the main camera body. Leave all the flat ribbon cables connected, resist the temptation to pull them apart or separate them.

4. Next to the shutter button there is a small plastic catch (see picture below) that holds the front of the case, unhook that and the front part of the case slips out a little. Do not try to pull it all the way out, see next step.

5. Next disconnect the ribbon cable shown in the picture below as “Pull this” by pulling it out of the white socket.

6. The front of the camera should slip out all the way and the camera separates into three pieces. Note that the back piece is still attached via a ribbon cable to the middle piece.

6. Unscrew the 3 silver screws and the two black screws marked with arrows in the picture above at step 5.

7. Carefully and with the camera lens pointing down (so as not to lose the filter), slip the camera lens assembly away from the PCB

8. The picture below shows where the filter goes. If you tilt the black camera lens assembly slowly, the filter will drop out. Also a square gasket may fall out that fits between the filter and the lens.

9. The picture below shows the original filter at left. I measured it at 1.5mm x 8mm x 9mm however simply taking the filter out and putting the camera back together will not do as the camera will not focus properly especially at the widest zoom setting. I didn’t have any special coated optical grade glass lying around so I experimented by cutting a piece of clear plastic from an old CD case. The thickness was about right and the CD case was crystal clear and free of scratches. The camera auto focus should compensate for small variations in the thickness of the replacement filter. In the picture below middle and right shows the top and side view of the piece I ended up with. The CD case is really fragile and I found that the best way handle it is to break out of it a piece larger than needed then using a very sharp knife (box cutter/scalpel) scour straight lines across the piece and snap it across these lines (just like when cutting glass). Later you can trim the edges with your sharp knife to make them smooth/straight.

10. Pop the new clear filter in place of the old one and reassemble the camera by reversing the above steps. Make sure you press the ribbon cable all the way back into its socket.

So far the mod has been done with minimal (zero) cost and the camera is IR sensitive however the pictures it takes are still colour but red shifted. To turn the camera into a true IR you might have to actually spend some money. Below is a picture of a similar camera where a 30mm lens ring is glued to the front of the lens. This allows you to screw on standard 30mm diameter filters.

The filter on the left (that looks like a black lens cap) is an infrared filter perhaps a R100 and will allow you to take true infrared photos. The filter on the right is a color correcting IR blocker filter (like a Xnite CC1) and restores the camera to normal colour operation (it replaces the original filter that was removed from within the camera and restores the colour balance).

Testing

The following photos were taken with the modified camera but without any additional filter fitted to it. Each photo is followed by its greyscale version. There was no processing done to the picture except scaling them down by a factor of 3.2 (and of course removal of colour in the grayscale version). As an aside here, you could go into the camera menu and set it to take black and white pictures. This would save you having to do this in post processing however I wanted to see what the raw pictures looked like for my own edification. The first two photos were taken on a cloudy day with fine drizzle, the next three were later that day, still cloudy but no rain. Bear in mind that these pictures captured both visible and infrared light so technically they are not true infrared pictures.

The next two pictures were taken by holding a large 87mm diameter acrylic IR filter (best guess 900nm) flush against the lens. Each original (scaled down) is followed by its greyscaled version. The photos were taken on a dry overcast day. These are true infrared pictures, note the typical dark sky (through small hole in cloud) and the light coloured grass and leaves in the foreground.

The next step would be to aquire a 30mm threaded filter ring and glue it to the front of the lens, then purchase some suitable 30mm filters to experiment with.

Some nice to haves would be the Hoya R100, RM90 and RM72 which pass 1000nm, 900nm and 720nm IR light respectively and also an XniteCC1 IR blocker color correcting filter or equivalent in case I want to restore the camera to taking normal pictures without actually opening it.

Click here to see more full resolution infrared photos.