Camera Obscura for Canon PowerShot ELPH115IS

Just in time for me to use it for [Worldwide Pinhole Photography Day](http://pinholeday.org/gallery/2016/index.php?id=819), here's a rather large attachment that allows a Canon PowerShot ELPH 115 IS to be used to capture pinhole images. To be more precise, it allows that little Canon to capture whatever image is projected onto the 150mm diagonal screen built-into the unit, and the front section described here makes that screen the target of a pinhole obscura.

Now you're probably wondering why