This article is featured on the Makezine.com blog...
'Success? Failure?' Rating: ★★★★★
I'm about to embark on an epic (for me at least) hiking expedition, and, in the name of minimising pack weight, my SLR is staying at home and my compact camera is coming out to play. But one thing I was potentially going to miss was the ability to use a polarising filter (most compact cameras have no ability to mount filters on them and my Canon Ixus 900Ti is no exception). I wanted to find a way to hold a filter in front of the my compact's lens in such a way as to: eliminate reflection from the rear of the filter; ensure the holder avoided blocking any of the sensors on the front of the camera, and; still be able to rotate the filter (a key requirement for using a polarising filter).
The obvious KISS solution was a cut-off cone that matched the diameter of my filter at one end and the lens surround at the other (loose enough so as not to impede the lens in any way). The depth of the holder needed to be great enough to clear the lens at it's shortest/widest and longest/narrowest zoom. The holder was to be made of thin, black (to reduce reflectivity) plastic (waterproof/durable). The whole thing would be held together with black insulation tape, which is strong, but removable, if I ever want to recover the filter.
Filter Holder Calculator
The first issue to solve was how to accurately construct the section of black plastic. The maths involved is relatively straight forward, but I decided to write a 'calculator' to work out the numbers, and to get it to spit out SVG code that can be printed via your favourite vector graphics package (I use Inkscape). Please refer to the image accompanying the calculator to see what the numbers refer to.
SVG Code To Copy...
Once you've printed out a filter holder template (the grey bit in the resulting image) for your camera, stick it to some thin, black plastic and cut around the template. Join the straight edges with tape, and then tape the filter of your choice (in my case a polarising filter) to the appropriate end of the holder (I'd also recommend cleaning the filter before sticking it on). I found that the black plastic needed some reinforcement along the seam to keep it in a circle shape.
To use the holder simply slip it over the camera lens and hold it in place with your hand. Ensure that it does not interfere with the lens in any way (i.e. is loose enough around the base and allows the lens to assume any zoom position without making contact with the filter).
Filter Holder Case
The next problem was how to protect my new filter holder whilst out on the trail...
I found a tupperware-style container that closely matched the dimensions of my filter holder. The 'filter' end of the holder was padded with a wafer of foam stuck into the container. The 'base' end of the holder was held in place with a ring of foam stuck into the lid. The result grips the filter holder tightly and prevents it from rattling around inside the container.
One further addition I wanted to add to the case was a camera tripod screw. The idea here is that the case will act as a stable 'foot' for the camera when I want to sit the camera on a wet or irregular surface.
I hot-glued a camera tripod screw (salvaged from an old tripod) to the case, and surrounded result in another foam ring. The foam ring supports the camera when it's screwed onto the case.
Attaching the screw resulted in a serendipitous blunder - I neglected to ensure the screw was perfectly perpendicular before the hot glue set. At first I thought that this was bad, but upon attaching the camera I noticed that I could correct for off-horizontal surfaces simply by turning the camera. And when sitting on a horizontal surface there are two places on the screw where the camera is horizontal (one pitched slightly forward, and one pitched slightly back). The sum total of which is a vastly more useful 'foot' than one where the screw is perfectly perpendicular!
Pros: A very simple solution.
Cons: A very simple solution.
Enhancement Suggestions: A 'hands free' option (i.e. some way to temporarily attach the holder to the camera that doesn't block the ability to rotate the holder).
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