RF 100-500mm F4.5-7.1 L IS USM, Auto Focus focuses too close

[carl_schnurr]

I just returned from a great week in the rainforests of the OSA peninsula in Costa Rica.
I took a lot of photos of birds and monkeys high up in the trees.
I had difficulty as the the AF seemed focus very close.  I had to manually focus farther out before I could get the AF to zero in on my subject.  Alternatively I could find something close to focus on and gradually raise the camera so the subject gets progressively farther away, until I was pointing at the subject.
This issue eliminated any Bird in Flight photos for the entire trip.

Here is my set up.

• R6 Mark ii
• Manual Mode, Auto ISO, with max set to 6400, typically wide open aperture.
• AF set to Animal Eye detect, Case1.
• RF 100-500L lens, with buttons set to 3m to infinity, AF ON, Stabilizer ON, Stabilizer Mode 1.

I tried varying the following camera settings but didn't notice any difference

• ONE SHOT and SERVO AF
• Different AF area shapes
• Whole Area tracking Servo AF ON/OFF
• Back Button Focus ON/OFF

Here a couple things that were different.

• Before leaving I thoroughly cleaned the front and back lens elements, both sides of my UV filter and the electrical contacts on the lens and camera
• The heat and humidity were fairly high, the first time shooting there was a build up of condensation on the back lens surface which evaporated immediately when I removed the lens for a minute.
• This is my first time using a USB charger for the camera batteries, and they appeared to fully charge as desired.

I also took a RF24-70 f2.8 lens which did not show any of these problems.

Since returning I have been trying to trouble shoot this issue.
I set lens to 500mm, f7.1, with camera touchscreen closed to avoid any errant touch screen focusing.
I tried several ISO/Av combinations with the same results.

With camera set to ONE SHOT, I am able to turn the focus guides ON; and they become visible when I manually adjust the focus ring.  When I have the lens focused on an object far away and then aim the AF point an object 7m away from the camera, it cannot achieve auto focus, and the focus guides are grey until I manually focus to get close to the subject being in focus.  Similarly when focused on object 7m away, and then aim the AF point at an object 4m away, it cannot achieve autofocus; and the focus guides are grey until I manually focus to get close to the subject being in focus.

Camera set to SERVO AF, focus guides are not visible, (should they be?)
Essentially the same result, except instead of focus guides being grey, the focus point is coloured Red, until I manually focus to get close to the subject being in focus and it turns Blue.

The lens needs to be fairly accurately dialed into the correct focus distance for the AF to kick in.  Do you recommend getting it repaired, or is there something else I can try?

[deebatman316 · Accepted solution]

A UV Filter is not necessary on digital cameras. There is one built into the image sensor of every digital camera. Focus Guides are only used in MF. I would turn off Preview/ Continuous AF off. Then enable lens drive when AF Impossible.

[March411]

Hi  Carl, welcome to the site and sorry to hear you are having challenges with the RF100-500mm. I run the same gear so hopefully I can offer some helpful assistance. 

To start with I would have to agree with deebatman316 and remove the UV filter. Once removed please look at the front and rear elements to ensure that there is no streaking or residue. Also, what did you use to clean the lens. 

Like I said I shoot the R6 MkII and the RF100-500mm and so far (knock on wood) it has been flawless. Since you used the RF24-70 f2.8 without issue it really does point to the RF100-500mm having some type of issue. I would remove the filter, make sure the elements are clean and try some test shots. 

For what it's worth, and I am not saying these are the best settings but this is what I use on my R6. It has worked very consistently for me. 

AF setting

Tab one
AF operation to Servo
AF Area to spot but when the lenses struggle, I will change it to nine points. High skies for birds in flight this becomes more accurate
Whole area tracking servo to off
Subject to detect Animals
Eye detection Auto

Tab 2
Case A auto when I shoot wildlife
Case 4 if it’s strictly birds

Orange camera Menu
Go to customize buttons
Shutter – meter only
AF on button (next to joystick) set it to eye AF, looks like an eye with AF written on top
* Button set to metering and AF start

I set my ISO, shutter speed and aperture to my desired base settings, go the wrench menu and save it to one of the custom shooting modes.

A couple things to keep in mind, if the camera goes to sleep you will lose any changes you made to ISO, shutter speed and aperture. I keep extra batteries with me always and my sleep setting is 5 minutes. When shooting wildlife, I really want the camera ready when I bring the viewfinder up to my eye.

My lens settings rarely change unless I mount my rig on a tripod and then the IS is shut off.

Normal lens settings
Always on Full – it will slow down the AF but allow me to track wildlife regardless of distance
AF-MF normally AF unless I am shooting subject very close
Stabilizer On/Off – Always on unless mounted on a tripod
Stabilizer mode - 1

Good luck, if you continue to have issues I would reach out to Canon support at this number 800-652-2666

[carl_schnurr]

Hi Demetrius,
Thanks for yoru reply.
While in Costa Rica, I tried removing the UV filter but it had no impact. I repeated it as part of my trouble shooting and it found the same.
Yes the focus guides are intended for use only in MF. But I as a troubleshooting tool, I found I could use them with the AF turned on as I could manually adjust focus into the ball park and then let AF kick in.

[carl_schnurr]

Hi Marc,
Thanks for yoru reply.
While in Costa Rica, I tried removing the UV filter but it had no impact. I repeated it as part of my trouble shooting and it found the same.
I use a lens cleaning kit purchased at a camera store, including a blower, brush, cleaning 'pen', lens cleaner and micro fibre cloth.
I placed a drop of lens cleaner on the glass, and cleaned with a microfibre cloth.

[carl_schnurr]

I now believe this is some sort of intermittent issue.  It was constant in Costa Rica, but first thing this morning, I repeated my troubleshooting with a fully charged battery, and the AF was bang on.

There are a few rabbit holes I'm going down to investigate

• affect of battery % charge, SLEEP/WAKE cycle, and USB vs 120V wall charger
• condensation / cleaning
• The AF3 setting 'Lens drive when AF impossible'

It will take me a couple days and I'll keep you posted.

[March411]

Hey Carl, I have to ask, where did you stay in Costa Rica. We recently did Nayara Springs and I am hoping to go back and do it again. The country side and forest are some of the most beautiful I've ever seen!

Anyway, it sounds like you made some progress. The lens does have two Nano USM motors for its auto-focus and I have seen mine struggle when the battery gets low. 

When you do additional testing you may want to keep track of the battery you are using in the camera. If you have multiple batteries one may be going south on you. 

And good luck on further testing. 

[carl_schnurr]

We have been to Costa Rica twice and stayed in the OSA peninsula each time.  It is truly gorgeous.
Our first trip in 2008, we stayed at a El Remanso Rainforest Lodge.  We really liked it.  This year when we wanted to return to OSA, we looked into it and the prices are way beyond our means.

My wife found a place called OSA Conservation Campus, overnight visitor.  Its definitely not for everyone.  We were over the moon with this place but it is rather niche.  Its essentially a ecological research facility /turtle hatchery.  They have staff and researches doing their work.  On the side they two types of accommodation,

• Exclusive OSA Nature Retreat, which is 6 separate beautiful homelike units each with their own private pool
  
  
• Conservation Campus Overnight Stays which is not your typical tourist experience.  There are 3 cabins each with 2 baths and 3 bedrooms.  The rooms are rented out individually.  The cabins sit in the middle of the campus, meals are provided in the same dining area with the ecological staff, interns and volunteers.  No bar, not much fuss, very much a self directed experience.  We loved it.
  

[March411]

Sounds like a very cool experience. Like you said it may not be for everyone but my needs are pretty small when traveling. I appreciate the information!

Now, when do we see some images 😉

[Waddizzle]

The advice to stop using the UV filter is sound.  If you feel the need to cover or protect your front element, then use a high quality Clear filter.

I strongly suggest that you stop cleaning your gear with fluids, especially inside your lens or camera. Solvents are for the exterior.  Experts are for cleaning the interior.

Photographing wildlife surrounded by leaves and branches is most often quite challenging, as you seem to have discovered. The camera has natural tendency to want to lock focus on the nearest subject to the camera. 

Every difficult scenario is a little different.  There will always be a scenario where you cannot get the shot you want.