Kenko extension tubes
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- Paul
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To maximize DOF try around f16
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- David
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I've got some of the cheapo tubes (£7) a set and was wondering if there was anyway of setting the aperture when they are on. Obviously there's no electrical connection and the camera just shows f/00. Do I set the aperture before I take the lens off the camera?
Keenbfb
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- Karl
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There is a trick to this and I'm sure someone will correct me if I'm wrong as it's been a long time since I tried this.
Turn on the camera and set the aperture to your required setting now press the dof preview button and keep it in, then press in the button you use to remove the lens and give the lens a half twist to break the electrical connection, now turn off the camera and you can also release the dof preview button.
Put the extension tubes on the camera along with the lens and you can now use the lens with the aperture you slected. It will still show as f/00 on the screen as the lens has no electrical connection with the camera but the aperture will be retained by the lens.
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- Richard
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It's exactly the same as with a macro lens of similar focal length. You may find this website of interest http://www.texasmothman.com/tutorials/macro_method.asp
I have a set of Kenko Auto DG tubes for my Nikon and find that they work remarkably well when used in conjunction with the AF-S 70-300 VR, especially between 70 and 150mm where that lens is particularly good and it's a much cheaper alternative to either the Nikon 105mm f2.8 VR macro or the much respected Sigma 150mm f2.8 macro!
I find that focussing your lens at it's closest distance helps reduce the need for stacking and you soon get to know which tube(s) to use for a given distance with your lens of choice. Try to avoid stacking where you can as multiple interfaces impairs the perpendicularity of lens/sensor.
Considering that it's fairly normal to use a macro lens at small apertures to achieve a decent DOF, so lens diffraction starts to dominate resolution, so the differences between tubes and a dedicated macro lens are really quite small. It is important however to use a lens that has a decent flat field performance, such as a decent mid range telephoto or tele-zoom, as field curvature is best avoided at macro distances, macro lenses are specifically designed to perform well in this respect, try to avoid "standard" zoom or wide angle lenses.
Also, being relatively small and light, I find the tubes easy to fit into my bag(s).
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