5D MkIII/100-400L lens/2.0X III extender?
I have a Canon 5D Mark III and Canon EF 100-400/4.5-5.6L lens. I am looking at Canon's EF 2.0X III extender. The Canon website says the extender is compatible with this lens but it says you should check your camera body manual for specifics on using with your specific body. I searched the manual and can find where autofocus works with the 100-400 lens but I don't see it listed with the extender like it is for some other lens.
Does anyone else have this combination? Does it work? Does it autofocus?
the lens and extender are compatible. you loose phase detect autofocus (regular autofocus) but can use live view in ok light. the image quality will generally be poor. you are also starting at f11 wide open.
...For instance you might appreciate the review in this url, namely the 2nd and 3rd paragraphs (all the content is good though).
the lens and extender are compatible. you loose phase detect autofocus (regular autofocus) but can use live view in ok light. the image quality will generally be poor.
What's even more poor is shooting the same subject from the same distance, with the same shutter speed, 1/4 the ISO, the same physical aperture, and no TC, assuming that focus is achieved in both situations.
you are also starting at f11 wide open.
Other than the AF issues, that's irrelevant. The same amount of subject light is collected as with f/5.6 and no TC; in fact, if you shoot at f/11 at ISO 400, and f/5.6 and ISO 100, AOTBE, you get more subject-level noise at ISO 100 without the TC, with Canon DSLRs; almost 4x as much subject-level read noise. At the higher end of the ISO range, say starting at ISO 1600 f/5.6 vs ISO 6400 f/11, the quantity of subject-level read noise is the same, but the quality is different in that the f/11 with TC has finer subject-level noise, both read and photon.
Also, relative to subject size at the same distance, using the same shutter speed and physical aperture size, with a TC,
- the DOF is the same.
- diffraction the same.
- the Bayer CFA pattern is finer.
- the radius of the AA filter is smaller, so an AA that is too strong has less influence on the subject
- an insufficient or absent AA filter will give less aliasing.
A TC is used to spread the subject over more pixels to get more detail, to have more relevant metering, and to see the subject better in the viewfinder.
A TC is not for getting maximum "image" quality or "pixel" sharpness; it is for maximum subject quality.
The 2xIII is a very good TC with very little loss of contrast or haloing; the only significant subject quality loss one may encounter is failure to focus manually due to a lack of experience, or you may miss a shot completely because live-view AF is too slow. I have used two 100-400s over the past 9 years, and have probably taken 1/2 million shots, mostly with manual focus. I do not regret learning how to MF early on.
If the OP wants to use PD AF, I would suggest getting a Kenko Pro 300 DGX 1.4x (must have the 'X' - not the DG), which somehow tells the camera to AF because it's not there, but reports itself anyway to the camera and EXIF (IOW, it will say f/8 on the camera, and in the EXIF, but the camera will PD AF the lens). A 2x will not allow PD AF an f/5.6 lens at all, I would think, except maybe the 1D cameras that officially AF at f/8 in the center point. 1 stop is about all that you can cheat the official limits of the cameras; beyond that, AF is not just slow, but non-existent, with endless hunting that passes right by focus without even noticing it.