The 1.4 EX is placed between the lens and the camera, and it allows the photographer to use the 70-200mm f/2.8 lens as a 98-280m f/4 lens, and the 300mm f/2.8 lens as a 420mm f/4 lens; the high optical performance is maintained and the AF speed is not affected.
Usable Lenses and Combinations
Sigma APO Tele Converter 1.4x and 2x are dedicated Tele Converter lenses, which should be used with listed lenses only.
AF function of Pentax mounts cannot be used with SFX/SF7 cameras.
Do not use the APO Tele Converter EX on top of another APO Tele Converter, or any other kinds of converters.
To check compatibility on the Sigma Website, click here.
Attaching the APO Tele Converter to the Lens
First, attach the APO Tele Converter EX to the master lens. Then, attach the lens and the Tele Converter to the camera body. If you attach the Tele Converter to the camera body first it may cause a malfunction.
If using a lens with a MINOLTA AF and attaching the APO Tele Converter EX to the camera body first, it may cause the AF mechanism to run idle.
On the lists, the lenses marked "AF" will retain auto focus operation when used with a Tele Converter. The lenses marked "MF" can only be used for manual focus.
Some lenses will operated in AF even though the list of MINOLTA AF, NIKON AF, PENTAX AF mentioned "MF", however, be aware that these lenses cannot focus precisely by auto focusing. Therefore, please use such lenses in MF mode when a teleconverter is attached.
*1 With 1.4x APO Tele Converter, AF can operate between infinity and 1.2m. If the subject is closer than 1.2m, only MF is available.
*2 With 1.4x APO Tele Converter, AF can operate between infinity and 0.52m. If the subject is closer than 0.52m, only MF is available.
*3 When the Tele Converter is attached, the zoom range will be restricted to between 100mm to 500mm.
Using the APO Tele Converter EX decreases the effective aperture by one F-stop (with 1.4x Tele Converter) or by two F-stops (with 2x Tele Converter).Regardless of exposure mode, correct exposure can be obtained.
If using a lens which has "o" in the list, the camera's display will indicate the converted exposure information. If using a lens which does not have "o" in the list while using a hand-held exposure meter, you should increase the exposure reading by 1-stop for the APO 1.4x Tele Converter EX or by 2-stops for the APO 2x Tele Converter EX.