If you are a hardcore Holga fan or have already taken the time to look up some sites featuring Holga mods and hacks (or to take apart your camera for that matter), you will know that the Holga, despite sporting a switch for two different aperture settings for sunny and cloudy conditions, only features one aperture. This is due to the fact that switching from cloudy to sunny causes an arm to slide in front of the lens opening, the area of the hole on that arm (which is supposed to allow less light in) is larger than that of the aperture; i.e. the amount of light remains the same.
See what you can do with your Holga when you DON'T use the 12 or 16 mask. It's naked, leaky, and overlapping fun. I have been using my Holga without either the 12 or 16 frame mask and have been getting some really nice results. I love the exaggerated vignetting and light leaks that occurred on every picture. These pictures all came from The Art of Waiting roll from September 2010, shot on Fuji Velvia.