Extension tubes are hollow accessories that fit between the camera body and the lens to alter the minimum focusing distance. The practical result is that we can get closer to what we want to photograph, project a larger image onto the sensor and thus achieve a more detailed photograph.
These accessories are sold in the form of combinable sets of, usually, two or three pieces of different lengths. They can be used with any type of lens, prime or zoom, although care must be taken when working with wide angles because the minimum focusing distance can be found inside the lens.
Extension tubes with electronic contacts for Sony A (Minolta AF)
Some models have electronic contacts that allow the camera to communicate with the lens, and some do not. It is important to remember that if they do not have contacts, you will lose control of the aperture from the camera and will only be able to use the lens at its maximum aperture, unless it has an aperture control ring. As this is a very cheap accessory, buying extension tubes without connections and therefore without the possibility of aperture control, autofocus or saving of EXIF data seems to us to be a great way to waste money.
Some brands make their own sets of extension tubes with complete electronic contacts. As far as we know, there are no tubes made by Sony for their A-mount system, so you have to turn to third party brands.
Since extension tubes are only spacers and do not contain optical elements, it is much easier for these third party brands to sell Sony A extension tubes with electronic contacts of reasonable quality.
Magnification ratio
Roughly speaking, extension tubes offer a magnification ratio of between 0.2 and 0.4. Simplifying, a magnification ratio of 0.3 will mean that the size of a 1cm object will be 0.3cm on the camera sensor at the minimum focusing distance. If you are photographing large insects or flowers, for example, which are already larger than the sensors, that magnification ratio will be more than enough.
FAQ
- Cost: Extension tubes are a mere fraction of the price of a macro lens. They seem like the most logical choice if you’re unsure whether macro is for you and just want to try them out.
- Compatibility: Tubes with electronic contacts do not present compatibility issues with any camera or lens model (with the exception of wide angles), although communication between lens and camera is somewhat slower.
- Image quality: Loss of quality is minimal due to the lack of optical elements, although they can cause vignetting.
- Difficulty of use: None, although using the tubes causes a significant decrease in light reaching the sensor and changes the effective f-number.
- Expected results: Magnification ratio between 0.2 and 0.4.
- Size and portability: They are light and easy to transport. They do not need to be specially protected.
Examples of photographs taken with extension tubes
Buy macro extension tubes for Sony Alpha (A-mount / Minolta AF)
Fotodiox
Compatibilidad con:
Minolta 7000, 9000, 5000, 7000i, 5000i, 8000i, 3000i, 2xi, 3xi, Qtsi, GT, 5xi, 7xi, 9xi, 300si, 350si, 400si, 500si/550si, 505si, 600si, 650si, 700si, 800si, Dynax 9, Dynax 7, Dynax 5, 40, Maxxum 5D, Maxxum 7D; Sony A900, A850, A99, A99 ii, A100, A700, A200, A300, A350, A230, A330, A380, A500, A550, A450, A290, A390, A560, A580, A33, A55, A35, A65, A77, A57, A37, A58, A77 ii, A-68
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