The improvised one here was just too crazy to use. Everything had to be held together with tape, string, and luck.
It turns out it's pretty easy to hack a macro lens, if you already have a short zoom lens you don't need.
There are a lot of canon kit lenses that came with the cameras floating around out there for only a few dollars. The best price I saw was $3.98 US.
The lens I'm using is a canon EF 35-80mm zoom. I got it for free from someone who paid around $5 for it in Japan.
The object here is to remove the front lens element.
My screws were found under a sticker, but different lenses hide the screws in different places.
The sticker is useless after you remove it, so don't try this unless you want the change to be permanent.
That's the wrinkled corpse of the sticker in the background.
This lens cluster does the focusing as far as I can tell.
At this point you can take a macro shot, but the lens will leak a lot of light onto your censor. The black plastic surround covers a gap between the outer lens casing, and the inner sleeve that controls the zoom.
If you were trying to do this as a temporary thing, and wanted to try it before you commit, all you need to do is cover the lens front with something light proof with a hole around 2cm in diameter in the centre.
I'm guessing gaffer tape would work well.
The main thing is to create a cover for the gap between the outer casing and the inner zoom sleeve.
A clear glass filter, or a UV filter will be the thing that keeps dust out of the lens.
The large black plastic thing is the bit we are keeping.
The results are pleasantly surprising. The original lens could zoom into around 6cm in width. This is closer to 1cm.
The focus ring no longer does anything, but the zoom still zooms.
There are two ways to focus.
Moving the camera or the subject until the scene is in focus is where you start. The distance from the lens that the subject needs to be is only around 5cm. Once you have the subject roughly in place, you can use the zoom to change the point that's in sharp focus.
The zoom also works as a zoom, and changes the field of view between 12mm and 25mm from one extreme to the other. ie at full zoom (as per the shot of the pencil, you can fill the frame with a 12mm object)
All in all, not quite as functional as a proper zoom lens, but for $5 it represents a pretty good compromise, and something I'd call a total success.
120 Things in 20 years - If canon just made the front lens element removable, I wouldn't have needed to do this lens hack to convert a zoom lens to a macro.