Extension Tubes

What are extension tubes?
Extension tubes extend the lens away from the camera body, so increasing the possible closer focus of any given lens. Primarily, these are best used with a standard/short telephoto lens.

How many do I need?
Often extension tubes are sold in sets containing two or three tubes, depending on manufacturer. Some may be made for just one lens, eg the Nikon PK13 which is designed to fit a Micro-Nikkor 55mm lens F3.5 + F2.8 enabling it to focus at 1:1 life size magnification which means that the size you see on screen is the size it is on the sensor or film plane.


Extension tubes for Micro Four Thirds, Micro Nikkor and Nikon autofocus

Most extension tubes, these days, are capable of being fully automatic and will not only convey the autofocus but also the metering to most camera bodies. Best check this out before buying them. So in many ways this is a win-win scenario for people wanting to explore close-up photography.

They have the main advantage of being affordable, also they may fit with a lens that you already own. They are generally small in size, lightweight and easily fit into a camera bag.

You’ll either fall in love with them, use them occasionally or not at all. I am an occasional user. If I am going out with a small kit for day photography I may leave my Macro lens at base. Some people I know find that they can be a bit of a fiddle to use. You put them on the back of the lens first then mount them to the camera body. However on my Panasonic with its focus peaking they are very easy to use. Once fitted to your lens, they limit the field of view to a small area. Only this view will be captured.

You will inevitably need to increase your exposure due to the lens being further from the image forming plane (sensor or film) plus being closer to the subject and therefore reducing the light available. Your Depth of Field is also extremely limited. You will be having to use an aperture of F16, F22 or even F32 to have any real DoF.

Micro Nikkor fitted with PK13

What else would be useful?
Personally I would highly recommend a good tripod and a cable release of some sort. If you don’t have a cable release use the camera’s self-timer. If you are shooting bugs, pray they don’t fly away. Flash is another tool that you can use. It’s not for me because it’s yet another expense and more to think about and carry around with you.

Is there a down side to them?
Yes, like most things. You may reduce the amount of light hitting your subject because you personally are closer to it. If you get too close to bugs and things they may fly away. You could end up on top of your subject, being just a few centimetres away from it.

What is the plus side of extension tubes?
The cost of them is really good compared to a true macro lens. As there are no glass elements in an extension tube I personally don’t feel a need to be brand loyal which results in a big financial saving as well. If you can get the lighting and Depth of Field correct then you should hopefully have a very different view of the subject. Size and portability for me are a big plus.
Both Colin and myself have a PK 13 extension tube for our Micro-Nikkor 55mm lens.
M

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