EOS 90D Autofocus Issues with EF 100-400mm L IS II USM

[canon_eos_90D]

I recently bought a Canon EOS 90D body.

Unfortunately I'm encountering focus issues when using the body with the Canon 100-400mm L IS II lens.

When I'm trying to focus (using OVF) on an object (like a race car for instance) that's coming towards to me, the camera/lens won't focus.

The settings on my camera are: Autofocus > AI Servo, shutterspeed: 1/1000 - 1/2000. Normally those shutterspeeds should deliver me a sharp picture. But that's not the case.

When I attach the lens to a Canon 6D or 5D Mark IV I don't have any problems at all; the focus issues don't happen with those two bodies.

I know when a subject moves closer to or further away of the camera, the sensor can have some difficulties in focussing. But with the fast shutter speeds I should get sharp images, which is not happening with the 90D body.

Anyone an idea how I can solve this issue?

[jrhoffman75]

Do you have a filter on the lens?

Some posters have reported problems that are resolved by removing the filter.

[ebiggs1]

This is worth repeating, "A fast shutter speed does NOT correct auto focusing issues."  In fact it may make it more difficult for the camera. IMHO, I would never use Ai-focus. Ai-servo can be of some help but it will fire even if focus is not achieved. Result, blurry photos! You might want to just use the reliable standard One shot and just the center focus point.

BTW, "Do you have a filter on the lens?"  If so remove it. The 100-400mm doesn't do well with filters even good filters. 

[canon_eos_90D]

Thanks for the info!

Will try with the fliter removed from the lens.

[jrhoffman75]

Can you post a RAW file that you designate as poor focus on Dropbox or One Drive and post the link here?

[canon_eos_90D]

Hello John,

Will do.

[wq9nsc]

For situations like that, your 90D MIGHT need to use a single focus point and the one in the center of the array is the desirable point for highest performance of the camera/lens combination.  If you can put and keep that single focus point on an area with some contrast, the camera is going to be able to provide its best AF performance in the extremely high closure rate situation you describe.

Every little delay where the camera has to "think" reduces your odds of getting solid AF lock in the short time interval it has to work with a rapidly approaching race car.  You know your subject is moving rapidly so do NOT use AI focus mode because that can create a slight delay for the camera to decide to switch from one shot to servo mode as it begins to find a focus target, AI servo is the proper choice for your shooting situation since the subject is always moving.  That is the same reason for defining explicitly the focus point the camera uses even though that does add to the requirement that you frame perfectly because otherwise the processor is trying to choose the best AF point out of the array and will often start switching AF points preventing focus lock in the short time period it has available.  It is a case of you having to work with the camera body to do the best both of you can do with a VERY difficult subject.

I have never shot a 90D but I have shot a lot of different sports with my 1DX, 1DX II, and 1DX III bodies which have the best servo AF performance that Canon can deliver and even with those bodies for tough shooting conditions I have to work with the camera to give it the best chance.  I use single point AF quite often and although I shoot primarily with the "great white" primes which focus extremely quickly, when possible I have the lens pre-focused at a good starting point.  This isn't something I can do all of the time with field sports but in many cases you can give it a good starting point since you know when and where the car will appear.  When appropriate, I use the focus range limiters on the lens to further improve system performance.

An approaching car at speed is an extremely difficult subject for any AF system given the speed of closure.  The 90D is a new body but it may still be lacking in AF performance to the older but more expensive 6D and 5DIV bodies.  A lot of road course shots are taken with cars entering and exiting turns and other "course features" not just for the drama but also because it is far easier for the camera AF system.  You may have to fine tune the AF servo settings for tracking sensitivity under the AF custom menu to make it more responsive to very high speed of closure situations, fortunately you can adjust and test those settings with traffic running at fast interstate speed to get a good feel for how the adjustment affects AF performance. 

Always start tracking the car as quickly as possible to give the servo system time to lock and adjust to closure speed before it reaches the spot where you want to capture images.  Based upon how far ahead you can track the vehicle and the type of track MAY cause you to rethink the sensitivity settings for the AF servo system under custom function II-2 and also the settings under the same tab for focus versus release bias.

Rodger

[canon_eos_90D]

Thank you very much Rodger.
That's something to read and experiment!

[wq9nsc]

You are VERY welcome! 

Most of the time when I shoot a different type of sport or at a new venue, I find that I will modify my expected setup a little bit during the pre-event warmup activities and a bit more if I shoot there again.  There are a lot of variables with the different bodies, lenses, events, etc. so iterating to optimal often takes a few times and suggestions in the manual and on the web are just a starting point.

Good luck with your setup!  And you will also need to experiment with which part of the car provides the most consistent focus spot for the camera.  I run into this issue in field sports where some uniforms provide a large area where AF works well while others require you to target a small area of the uniform for fast and consistent focus. 

With field sports, sometimes I can use a larger array of focus points but much of the time I need to be able to direct the camera to choose exactly which player in a dynamically changing group and that usually means a single point with more of the workload transferred to me.  I know that Canon is working once again with eye tracking technology to detect where the photographer is looking in order to automatically choose the focus point but I doubt if that technology is going to work well for most sports where you are constantly looking between what is happening now and what is probably going to be important next. 

I saw a humorous comment that the eye tracking focus really won't work well for boudoir photographers who may be staring where they shouldn't

Rodger

[ebiggs1]

"For situations like that, your 90D MIGHT need to use a single focus point and the one in the center ..."

Correct and why I usually recommend people use this set up.  A lot of the time we tend to over think it because our cameras can do so much when in reality the simplest solution is the answer. Its hard to beat One shot and the center focus point.

[ebiggs1]

"... which part of the car provides the most consistent focus spot for the camera."

This is also a good point. If the race cars are shinny it may not give enough contrast for the AF sensor to pick up on it quickly.

If there is lettering like sponsorship logos that might be a good spot to use.