Improve close ups / macro capabilities of a lens

Using the kit lens (or with a telephoto lens) we can produce a closer image without having to invest to much in a macro lens, one possibility is to get a close up filter or use macro extension tubes. This kind of techniques allows you to get closer to the subject expanding the imagem, a magnification by close up and not by zoom.

Close up filter

A macro filter is a converging (positive) lens (positive meniscus or concave-convex), the graduation is proportional to the magnification power. With this filter, the focal length of the lens is smaller, allowing the camera to be closer the subject and therefore the image appears larger.

Comercial close up filter and sample image

The optical effect of using a close up filter

With one lens, something to support it and glue (or just the lens and an hand...) it's possible to build a close up filter. A lens is not more than curved glass :)
I was not happy with the result of a +2 close up filter, and since a lens with 10 diopters was not expensive, I decided to build my own close up filter. A 10 dopters filter supported by a cokin filter ring's.
If the glass quality is poor is possible to see some optical issues, such as chromatic aberrations.

My filter of 10 diopters

Test image

Real photo using the close up filter (click to enlarge)

Extension tube

An extension tube typically (the cheap version) consists in several rings screwed in together to make a tube of 65mm that can be placed between the camera and the objective, there are no optical elements inside it and don't have electrical connections between the rings, this means that we don't have chromatic aberrations from the lens (since don't have any) and is impossible to use the autofocus and control the lens aperture.

Extension tube

At first I tried to put the tube into a telephoto lens, however the result was not the ideal.
With a telephoto lens I need to put the lens close to the subject, use all rings and the maximum zoom to get something interesting. This is not so good because we are too close (almost touching it); we are using zoom without a stabilizer (no wired connections in the tube) and if hand-held we need to use a smaller exposure time; and we have less light available.

All rings of the extension tube in a telephoto lens and with a macro filter / An example photo (click to enlarge)

I found interesting the result when using the smaller ring with 23 mm and photograph at 55mm with the kit lens, Canon 18-55mm.
This set is good because the lens is shorter and has less weight than 18-200 with rings...

Canon 18-55mm with one ring of the extension tube

Inverting the objective

One way to greatly enlarge an image is using the lens inverted, we just need an inverter ring for our lens. This kind of ring is screwed into the lens filter and atached to the camera bady, the eletronic contacts are exposed. To avoid problems we need to find a way to protect the lens, we can build a rear filter from a rear cap and a small piece of transparent glass or plastic.
In conjunction with the inverted lens we can put extension tube to increase the magnification power.
Since the image is greatly increased it's necessary that the camera be as stable as possible, using a tripod.

Exemplifying image of how works and results of an inverted lens (click to enlarge)

Without electrical connections between the camera and the objective we can set the aperture of the objective before dismount it. In Canon is possible to leave the objective with the aperture we want, you just need to press the "preview" button (when the camera is on) to set the aperture chosen in camera, at the same time we remove the objective.

Seting the aperture on a lens