Extension tubes - What are they and what exactly are their purpose?

[BenjaminJ]

Ive seen people mention having them but no idea what they are or what they are used for.

 

[Overread14 2]

Extension tubes are a clear (no glass) tube that is fitted between a camera and lens. The result is that the lens reduces both its maximum and minimum focusing distance. This renders the lens incapable of focusing further away (distance varies depending on the focal length and the amount of extension tube added; but can be to several feet down to millimeters).

The reduction in minimum focusing distance lets the lens move and focus closer to a subject and is thus the prime intent of most uses of extension tubes as it allows an increased close up magnification. It's a cheap way to getting to macro photography.


Note tubes come in two basic types, those with and those without metal contacts. The lack of contacts makes the tubes ultra cheap, but means that you've no control over the lens AF (not a problem as most macro is done in manual focusing) and lens aperture (big problem as using a smaller aperture than wide open is often needed for macro due to the small depths of field).

 

[BenjaminJ]

Thanks Overread.

 

[minicoop1985]

They were way more common in the days of manual focus film cameras, since all they had to be was a metal tube with a male mount on one end and a female on the other. For that, they're incredibly useful, actually. Here's an example:

Tiny forest by longm1985, on Flickr

Done on my Hasselblad with 40mm extension tube.

Basically, what I'm saying is, get an AF one, use your lens in MF, and control your aperture.

 

[iKokomo]

I got some extension tubes for 10 bucks on amazon and while you need a full manual lens for it! But if you can do that? They work amazing well!