Photography Hack a macro lens from a zoom lens

I decided to make a more permanent macro lens.

The improvised one here was just too crazy to use. Everything had to be held together with tape, string, and luck.

It turns out its pretty easy to hack a macro lens, if you already have a short zoom lens you dont 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 Im using is a canon EF 35-80mm zoom. I got it for free from someone who paid around $5 for it in Japan.

 The first step is to find some screws that might let you get inside.

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.

Removing the sticker revealed 3 screws.

The sticker is useless after you remove it, so dont try this unless you want the change to be permanent.

Thats the wrinkled corpse of the sticker in the background.

Undo the screws.

This allows the top lens element to be removed.

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.

In my lens, it wasnt possible to remove the lens from the plastic surround, so I had to cut it off.

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.

Im 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.

The lenses are of no use, but the plastic surround is very useful, because it has a screw thread to take filters.

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.

There was an extra hole that I filled with a screw to keep everything light tight.

A clear glass filter, and its all done.












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 thats 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 Id call a total success.

120 Things in 20 years - If canon just made the front lens element removable, I wouldnt have needed to do this lens hack to convert a zoom lens to a macro. 

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Stirling engines Balloon Power pistons

My original balloon power piston looked like this.

It had a connecting rod glued to the centre, and the other end of that rod connected to the cam shaft. The result was that as the air was heated in the chamber with the displacer, it expanded, filled this balloon, and pushed up the connecting rod.





I think it also pulls as the air cools and contracts, but that isnt very obvious either way. In that video (see link in first sentence) you can see the balloon inflating and giving the connecting rod a little push.

Im amazed that the air can expand and contract at such a high frequency. Im amazed these things work at all.

My power piston design was a little rough, and to be honest I was lucky that it worked at all.

The balloon kept slipping around under its rubber bands, making the connecting rod feel some resistance as the balloon reached its limits of free movement. The result was some extra friction where it wasnt necessary.

What I need is a bit more room for error.

With that in mind, I did some research and found what I think might be a useful design, and also came up with one myself that might work pretty well.

I found this one in use already and mine was made from a balloon neck, and a plastic bottle top.

To start with I created a plastic disk around 25mm in diameter by trimming off the sides of a plastic bottle cap. 

It was pretty easy to do with scissors, and a cut that went in a spiral gradually cutting away the side.

I also have a copper elbow that will be the power pistons basic form.

This will take the place of the ungainly plastic bottle with the hole hacked into the side as seen in the top-most picture on this post.

I cut the neck off a balloon and inserted the plastic disk. The connecting rod would be glued to the centre of this disk at the top.

The cut end of the neck is stretched over the copper elbow so that it looks like this when at its highest. (this would be the end of the power stroke)

And like this at its lowest.

It looks quite neat, and this is probably the design Ill use unless it proves to require too much air expansion to fill it.

My design includes the same section of balloon neck, and a cable tie to secure the top.

I tightened the cable tie with pliers  and then cut the rest of the balloon away with scissors.

It looks like this at its lowest. Or near its lowest.

It might be the case that this design will prove useful when used entirely at the low end. It requires much lass change in air volume to move 10mm up or down from its pictured position.







I have no idea if it will be of any benefit to use this (green) design, but It should be easy enough to try both with my adjustable cam shaft.




120 Things in 20 years - When it comes to balloon power pistons for Stirling engines, I have standards above which, I will not go.

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