Welcome to the photography-on-the.net Teleconverter FAQ
The single most thorough informational resource on Teleconverters in the World ©
If you can't find your answer here, you didn't read it all!
Here you will find the Extender EF 1.4x II compatibility chart , the Extender EF 2x II compatibility chart SIGMA Teleconverter charts, and much more.
Be sure and check out our Image Example thread as well found here;
Teleconverter/Lens Combination Sample Image Archive
What are Tele-converters/tele-extenders (T-cons)?
T-cons are small lens attachments that fit between the camera body and lens. They are used to increase the focal length of the lens in use.
I: CANON Teleconverters
Canon now makes four T-cons, in versions MkII and the latest MkIII
Extender EF 1.4x III
Extending a lenses focal length by a factor of 1.4x, Extender EF 1.4X III incorporates phenomenal optical performance with minimal chromatic aberration and is a perfect complement to many of Canon super telephoto lenses. It features a built-in microcomputer for seamless communication among camera body, lens and extender; features careful lens placement and coatings to minimize ghosting and flare and even has a new Fluorine coating that keeps soiling, smears and fingerprints to a minimum. An integral part of many professional systems, Extender EF 1.4X III maintains high standards not only optically, but also in terms of rugged, dustproof and water resistant construction.
Extender EF 1.4x II
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. It 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.
Extender EF 2x III
Designed to extend a lenses focal length by a factor of 2x, the redesigned Canon Extender EF 2X III delivers optical performance on par with the finest Canon super telephoto lenses. It features a built-in microcomputer for seamless communication among camera body, lens and extender, features careful lens placement and coatings to minimize ghosting, flare and chromatic aberration, and even has a new Fluorine coating that keeps soiling, smears, fingerprints to a minimum. Extender EF 2X III meets necessary standards in terms of rugged, dustproof and water-resistant construction, and should be in every professional's camera bag.
Extender EF 2x II
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.
The EF 2x II doubles the focal length of any lens it's mounted to, and reduces its effective aperture by two stops. With the EF 2x II, AF is possible with any EOS body if the lens has an f/2.8 or faster maximum aperture, and compatible Image Stabilization lenses maintain the IS feature when used with any current EOS camera.
Mk I Vs. MkII Vs. MkIII Versions
The current models of Canon EF T-cons are the "Mk III" versions.
Differences between the MkIII and the MkII include the following:
- Both T-Cons have had new optical designs
- The MkIII T-Cons include new Flourine coating for added protection fo the glass
- They have been redesigned to match perfectly the latest Canon MkII IS Super Telephoto line
Differences between the new MkII and the older Mk I T-cons include the following.
- Weather sealing was added to both
- The 2X had a complete overhaul of the optics
- The 1.4X remains the same design optically adding only the weather sealing and some new coatings.
- The MkII 2X T-con has been redesigned to allow "stacking" of the 1.4X behind it. This was not possible with the Mk I 2X.
It is important to understand that the use of a teleconverter is subject to a number of conditions, including the following.
- 1: The T-cons listed in these charts can not be used with all lenses. Only the lenses listed in the charts will physically "fit" Canon and SIGMA T-cons. If it's not listed. It won't "FIT". The reason they will not "fit" is because the front element of the Canon T-cons protrude forward into a recess found only on specific telephoto lenses, for a true matched optic that works only with these telephoto lenses. Other lenses do not have the space behind there rear elements to allow this protrusion to fit into.
- 2: T-cons will decrease the effective aperture of any lens to which it is attached.
- 3: In many cases, the increased f/stop will result in a loss of Autofocus.
In some cases, the use of a T-con will result in use of only the center AF point for autofocus.
- 4. Additionally, EF Extenders reduce lens drive speed. The EF 1.4x or 1.4x II reduces lens drive speed by approximately 50~67% depending on the lens in use.
The EF 2x or 2x II reduces lens drive speed by up to approximately 75%.
This speed reduction gives the AF system more time to detect focus. This can be helpful since the depth of focus is reduced with the longer effective focal length and the chance of defocus increases. However, the reduced tracking speed and smaller maximum apertures caused by the use of Extenders can be a disadvantage with fast moving subjects, particularly in low light.
- 5. T-cons WILL degrade the final image quality of the lens in use.
(the degree to which this is perceptible varies depending on the lens with which it is used)
- 6. T-cons DO effect Minimum Focus Distance. However, they do not alter the lens's optical working distance. The change in MFD, measured at the sesor/film plane is only due to the actual change in physical length of the total Optic in use as increased by the length of the T-Con itself.
Requirements for Auto Focus
- Canon makes SLRs with TWO distinct Aperture requirements for Autofocus. (AF)
- A: The 1 series can AF with apertures as small as f/8
Models include; EOS 1D, 1Ds, 1DMkII, 1DMkIIN, 1Ds MkII, and film cameras EOS 1 and EOS 3
- B: All other EOS bodies require f/5.6 to AF
Models include D30, D60, 10D, 300D, 350D, 20D, 30D, and 5D
Film bodies = all of them except for the 1 and 3
Calculating Focal length and Aperture
The math is simple.
- Multiply the lenses focal Length in MM times the T-cons "X" (1.4X or 2X) to find the focal Length that will result.
The same is true of f/stop.
- Either Multiply the lenses Max Aperture times the T-cons "X",. or simply add one full stop when using the 1.4X or two full stops when using the 2X