Extender EF 1.4X blurry pictures with EOS 90D and EF 100-400mm lens

[Dmcd3055]

I have a 90D and am using the EF100-400 f/4.5-5.6L IS IIUSM lens. I added the 1.4x extender to get greater distance. My concern is that I am not getting any pictures in sharp focus. Has anyone else experienced this? Whats the "fix" ??

[johnrmoyer]

The additional blur from adding the EF 1.4x III extender, if that is the one you have, will come from:

1. smaller aperture (small aperture diffraction blur can often be fixed with digital lens optimizer in Canon DPP software if you have the camera save a raw file)

2. A faster shutter speed will be needed because a small movement will cross more pixels on the sensor

3. Greater distance means that variation in the density of air will cause distortion and blur

4. Adding more glass will slightly reduce the sharpness

5. There will be a little less contrast for fine details

If you have a different extender, the problem is likely the extender.

If the blur problem is really a focus problem, then it may be because your camera is only able to use a center focus point when you have the extender on. If that is the case, then it will focus better in live view mode than when using the viewfinder.

[p4pictures]

Adding the extender reduces the effective aperture of the lens to f/6.3 to f/8 and f/8 limits the number of the camera AF points that work well as there is less light on the AF points. This is assuming you are using the viewfinder, not live view.

Depending on the model of extender the number of AF points that provide cross-type detection changes. 

• If you are using the Extender 1.4x Mk I or Mk II only the central AF point is capable of AF at f/8
• If you are using the Extender 1.4x Mk III the central block of 9 points will be cross-type AF points and two blocks of nine points to the side of the central block will also work as AF but only detect horizontal lines of contrast. 

It's best to look at the EOS 90D supplemental information document where this is covered. 

[normadel]

The fix is to read the manual for the lens:

https://gdlp01.c-wss.com/gds/6/0300017486/01/ef100-400f45-56lisiiusm-im-e.pdf

It tells you, on page 17, that AF is not possible with the extenders, and to use Manual focus.

[johnrmoyer]

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@normadel wrote:

The fix is to read the manual for the lens:

https://gdlp01.c-wss.com/gds/6/0300017486/01/ef100-400f45-56lisiiusm-im-e.pdf

It tells you, on page 17, that AF is not possible with the extenders, and to use Manual focus.

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The manual was not updated when newer cameras were produced. While I do not have the EOS 90D like the original poster, with my EOS 80D auto focus works using the center point at F/8 which is wide open and works using multiple points in live view. The EOS 90D has better autofocus than does my EOS 80D.

For example, this photo was auto focus through a bus window. EOS 80D, EF100-400mm f/4.5-5.6L IS II USM +1.4x III, distance about 200 meters, F/8.0.

From exiftool:

• [MakerNotes:Camera] AFPointsInFocus : 17
• [MakerNotes:Camera] AFPointsSelected : 17

A Grizzly Bear (Ursus arctos), also called Brown Bear, was pausing on the tundra while crossing a mountainside in Denali National Park, Alaska, United States on August 9, 2019.

https://www.rsok.com/~jrm/2019_Alaska/2019aug09_bear_IMG_9332c.html 

EDIT: I found the old raw CR2 file and edited it with a newer version of Canon DPP

A Grizzly Bear (Ursus arctos), also called Brown Bear, was pausing on the tundra while crossing a mountainside in Denali National Park, Alaska, United States on August 9, 2019.