DIY Camera Filter Swap on a Canon Powershot

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I wrote a few weeks ago about testing out a Schott BG3 filter on an SX260 for detecting vegetation stress remotely. That post and the results of this conversion are posted here. We’re now selling both those filters individually as well as pre-modified cameras at Event 38 for those interested in testing them out, but be aware before you grab one that the processes related to setting the right white balance, calibrating imagery to compare results from different pictures and even post-processing are not yet finished. We’ll be working on improving these but I wanted to make available what we have right away because there are some people interested in getting started right away. The process shown below will work just as well for any other filter you get anywhere else.

Before you start, it’s good to have a good selection of screw drivers, a brush, an air puffer, a marker and tweezers close by.

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To start, remove the back section of the camera by unscrewing 1 bottom, 2 right and 2 left side screws.

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Once the back is loose, pull it off gently and remove the flex cable by sliding it upwards out of the socket.

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Next, remove the bracket holding the right side of the LCD in place by removing the single screw at the top.

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Now the LCD is loose. Slide it a bit to the right so it clears the lip on its left side and then pull it up on the left side. There is a flex cable in the upper right corner that can’t be pulled too hard or it will come out. Accessing it to replace it is very laborious so be careful not to put too much stress on that cable! I use masking tape to keep the LCD up and out of the way while working beneath it.

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We’ll be unscrewing the 3 screws on the back of the sensor in a moment but first we need to remove the glue holding the sensor plate down. The glue is pretty tough, so I use a really sharp exacto knife to scrape it away bit by bit. Quick, light cuts work better and are less likely to damage something else than pushing hard so be gentle. Use a brush or air puffer periodically to remove the debris.

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Once the glue is out of the way, mark each screw’s position using a marker before unscrewing them. Make sure to set the screws aside in a way that you know which position to return it to later.

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Take the screws out and gently remove the sensor plate. Clean the area again to remove any dirt/dust that has fallen in. The reddish piece of glass in the center is the IR-block filter that normally keeps out all infrared light. Remove the rubber placeholder holding the filter in place.

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Remove the filter glass carefully using tweezers and set it somewhere safe in case you need to put it back in later.

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Clean the entire area again.

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Now carefully drop in your filter glass.

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Replace the rubber placeholder and then the sensor plate on top.

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Replace the screws in the right order and screw them in until the marks match up as closely as possible.

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Close the camera back up by replacing all the screws and brackets and don’t forget the flex cable on the back of the case. Finally you’ll want to check and make sure there’s no dust on the sensor or inside of the lens. Put the camera in Aperture priority mode and open up the aperture as wide as possible. Zoom the lens in all the way and focus the camera on something far away by half-pressing the shutter button. Now aim the camera at a clear sky or a white piece of paper and make sure it fills the entire screen. Take that picture and then look at it to make sure there are no black spots, below is the image as it came out of the camera used in this tutorial.

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If your image came out clean too then you’re all set! If you’re using a Schott BG3 filter, a quick and easy way to start processing images for vegetation stress is to set the camera’s white balance to the cloudy preset. This will allow you to process a vegetation index that represents vegetative cover and growth, although the results don’t yet cover the full scale of values as they would using a traditional multispectral camera.

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Comment by Jack Crossfire on August 24, 2013 at 4:59pm

The new cameras are a lot easier to get into than the ones 3 years ago.  That would explain the revival of IR hacks.


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Comment by Randy on August 24, 2013 at 6:29pm

very interesting.

You say, "although the results don't yet cover the full scale of values as they would using a traditional multispectral camera", I wonder how close it is..is it going to be good enough that it tells the farmers enough that they're happy with the lower-cost (vs a multi-spectral camera) or do they need the full range for it to be useful?  I just don't know enough about how useful this data is for farmers.

The canon cameras also have the chdk which is the most likely method used in the future to allow better interaction with the flight controller (i think).

Comment by HeliStorm on August 24, 2013 at 8:01pm
I have an older Canon point and shoot I have been considering doing an IR conversion on, but haven't worked up the nerve to open up. I got popped by a flash cap while repairing a camera for a friend a little bit ago, and it has left me a little gun-shy.
Comment by HeliStorm on August 24, 2013 at 8:07pm
I buy the Canon cameras for CDHK...good stuff. I got a point and shoot for less than $50 used to put CDHK on for a specific project attempting automated lightning photography. Amazing cameras for the price really. And many people sell them cheap on craigslist, etc.
Comment by Jose Pillich on August 25, 2013 at 8:17am

have you figured out a way to bring in the image into a remote sensing software package for analysis?

Comment by Jeff Taylor on August 25, 2013 at 11:44am

Randy you bring up a good point. Right now at this price point I think it's enough of a start even to just detect quickly if any particular area of a field suddenly dies or fills out faster than the rest. Later with a fuller range NDVI perhaps it will be useful for comparing different plots with different crop strains or different fertilizer density.

The flash cap is luckily not exposed on the SX260, at least for as deep as we have to dig in this case. :)

Comment by Jeff Taylor on August 25, 2013 at 11:45am

I've experimented with various custom white balances but haven't found one that gives a full range index yet.. will keep looking and maybe will have to change the filter in the end.

What software do you use for analysis? I'm just processing these in Fiji and viewing them there. Actually I just realized Fiji likely doesn't copy over the EXIF data containing the location so the output file is probably not even georeferenced right now.

Comment by Patric Millar on August 25, 2013 at 4:11pm

Great how to.  Anyone done it for a GoPro?

Comment by Gary McCray on August 25, 2013 at 6:43pm

Excellent how to.

It definitely makes it practical to convert yourself and is really nice that you have the filters and converted cameras available.

Do you also have or have access to a compatible filter that only passes near IR?

Comment by Jeff Taylor on August 26, 2013 at 11:46am

Not sure about GoPro - I think the filter glass on a GoPro might be mounted directly on the sensor. Anyway you can't use GoPro for mapping because of the wide angle lens.

I'm sure we'll be adding various filters including NIR-pass in the near future, I'll announce on Twitter/my blog when that happens.

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