Canon 1.4 Teleconverter
Back in 2005 I picked up a Canon 1.4x teleconverter and I've been using it
with my 300mm and 100-400mm zoom lenses. Teleconverters increase the
focal length (magnification) of a lens (in the case of the 100-400,
the increase is to 140-560mm - a nice little bump)
The teleconverter itself is quite small and attaches between the lens and the camera body. As it places more glass in the light path, there is a loss of light. In this case it is a full f-stop (quite expensive in terms of shutter speed). This loss of light also means that, on some len/camera combinations, there are issues with the autofocus system.
Except on the "1" series cameras, Canon’s autofocus system shuts itself down when a lens reports itself to be slower than f/5.6 - that means that the autofocus system does not work with my 100-400mm lens and teleconverter combo on my 20D camera ... unless I cheat.
In reality the autofocus system can be tricked into working with this lens/converter/camera combo as long as the light is fairly bright. It may seek a bit more than usual and at times it does fail to lock in a good focus but it can work.
The trick is to tape over some of the electical contacts between the lens and the camera body. This prevents the camera from being aware of the teleconverter's presence and therefore it doesn't realize that it has lost a stop of light! This trick also prevents the proper reporting of focal length but such are the costs of cheating.
The 300mm lens that I own is f/4 at it's maximum and has no problems focusing with the teleconverter as the combination is only f/5.6 - which is acceptable for achiving autofocus.
If you would like to try the tape trick yourself, here are the instructions:
Looking at the side of the converter that connects to the camera, rotate it so that the contacts are at the top. Place a small piece of tape (transparent is easiest to work with) on the 3 leftmost pins of the converter. Easy!
The 1.4x teleconverter is designed to be used only with certain telephoto lenses. It has a projection on the lens side that prevents its coupling with most lenses. In general, it will not work with non-Canon lenses. Towards the bottom of this article is a quote from the Canon website as to which lenses will work properly.
The image quality when using the teleconverter is still very good. Casual comparisons of photos with and without the teleconverter will not reveal any obvious differences.
Canon's offical word on this little item is below:
Extender EF 1.4x II
Lens Extender
This tele extender can be used with fixed focal length lenses 135mm and longer (except the 135mm f/2.8 Softfocus lens), and the EF 70-200 f/2.8L, 70-200 f/2.8L IS, 70-200 f/4.0L, and 100-400 f/4.5-5.6L IS zoom lenses. Superb optically, it preserves the image quality of the lens it's mounted to and multiplies its focal length 1.4x. Effective aperture is reduced by one f-stop; autofocus is possible on any EOS camera when combined with a lens having an f/4 or faster maximum aperture. The new version II maintains the outstanding optics of the previous version, and adds enhanced weather-resistant construction, and improved anti-reflective surfaces in the barrel.
The teleconverter itself is quite small and attaches between the lens and the camera body. As it places more glass in the light path, there is a loss of light. In this case it is a full f-stop (quite expensive in terms of shutter speed). This loss of light also means that, on some len/camera combinations, there are issues with the autofocus system.
Except on the "1" series cameras, Canon’s autofocus system shuts itself down when a lens reports itself to be slower than f/5.6 - that means that the autofocus system does not work with my 100-400mm lens and teleconverter combo on my 20D camera ... unless I cheat.
In reality the autofocus system can be tricked into working with this lens/converter/camera combo as long as the light is fairly bright. It may seek a bit more than usual and at times it does fail to lock in a good focus but it can work.
The trick is to tape over some of the electical contacts between the lens and the camera body. This prevents the camera from being aware of the teleconverter's presence and therefore it doesn't realize that it has lost a stop of light! This trick also prevents the proper reporting of focal length but such are the costs of cheating.
The 300mm lens that I own is f/4 at it's maximum and has no problems focusing with the teleconverter as the combination is only f/5.6 - which is acceptable for achiving autofocus.
If you would like to try the tape trick yourself, here are the instructions:
Looking at the side of the converter that connects to the camera, rotate it so that the contacts are at the top. Place a small piece of tape (transparent is easiest to work with) on the 3 leftmost pins of the converter. Easy!
The 1.4x teleconverter is designed to be used only with certain telephoto lenses. It has a projection on the lens side that prevents its coupling with most lenses. In general, it will not work with non-Canon lenses. Towards the bottom of this article is a quote from the Canon website as to which lenses will work properly.
The image quality when using the teleconverter is still very good. Casual comparisons of photos with and without the teleconverter will not reveal any obvious differences.
Canon's offical word on this little item is below:
Extender EF 1.4x II
Lens Extender
This tele extender can be used with fixed focal length lenses 135mm and longer (except the 135mm f/2.8 Softfocus lens), and the EF 70-200 f/2.8L, 70-200 f/2.8L IS, 70-200 f/4.0L, and 100-400 f/4.5-5.6L IS zoom lenses. Superb optically, it preserves the image quality of the lens it's mounted to and multiplies its focal length 1.4x. Effective aperture is reduced by one f-stop; autofocus is possible on any EOS camera when combined with a lens having an f/4 or faster maximum aperture. The new version II maintains the outstanding optics of the previous version, and adds enhanced weather-resistant construction, and improved anti-reflective surfaces in the barrel.