New (to me) EF 85mm 1.2 picks it's own focus point

[mattplatts]

I recently picked up a used EF 85mm 1.2 L II to use primarily on my R6 mk2. I've found that it tends to focus somewhere other than where I point it. When I use Spot or 1-Point AF, it seems to be looking around to find maybe the closest object, or maybe the highest-contrast object rather than what I have the focus point aimed at. It doesn't matter how much light there is - this can be in broad daylight or in low light.

As an example, taking a picture of a plant pot - I put the AF mark on the leaf or bloom that I would like in-focus, but the camera focuses on another leaf or bloom. I've tried opening up the AF options to larger areas, and that just broadens where it looks... and rarely focuses on what I intend. My expectation with Spot or 1-Point AF is for the camera to focus on that spot each and every time, assuming there is adequate light, which there is.

I've tried two different adapter rings, and that doesn't make a difference. I've also tried the lens on my daughter's Rebel Ti, and it works better there. That camera only has a few focus points, and the lens focuses on the point I select each and every time. Could there be an issue with the lens, or maybe this EF lens just doesn't talk well to an RF camera's new focusing system? I can send the lens back and try another one, but I thought I'd check to see if this is a common issue for this lens (or camera settings?) before sending it back.

Hoping that the community can clue me in on what I might be doing wrong!

[deebatman316]

The camera will always focus to something that's closer to it than further away. Also DSLR & SLRs use dedicated AF sensors for each AF point. This doesn't exist on mirrorless cameras the AF points are an illusion. The image sensor handles AF on a mirrorless camera. With mirrorless the AF system works differently than a DSLR or SLR camera do. You will need to adapt to using the AF system on a mirrorless camera. My first time using a mirrorless camera it didn't do what I wanted it to do. I had to relearn how to use the AF system on a mirrorless camera. The EF 85mm F/1.2L II USM lens is a very specialized lens and it takes time to learn it. Its not a fast focusing lens its known to be slow. It also doesn't support DPAF (Dual Pixel Autofocus) since its an older lens. This lens uses a Ring Type USM AF motor but with a twist. It has an Electronic Focus ring unlike most Ring Type USM which use a clutch under the focus ring to provide manual focus override. If you would like to use Full Time manual focus the camera must be set to One Shot. The focus ring is ignored with the camera set to Servo AF. Also Manual Focus After One Shot must be enabled in the camera menu. By default its set to disable and the focus ring won't work since the focus ring is electronic. EF 85mm F/1.2L II USM lens Manual 

[Tronhard]

I have a R6II  but not the lens you specify, however that should not be significant as focus point selection is really a function of the camera's focusing settings.
I too shoot single point focus, but as Demetrius said, left to itself, the focusing system will seek to find the closest object to the camera.   
Using button customization in the menu (Orange group 2nd from right, P3, item 4 on the list), you can assign a button to actually centre the AF point while focusing - so place the point you want to focus on in the centre of your view.  Because, in my case, I have that assigned to the SET button, I press SET and it should bring the AF point to the centre of display.  
This is from P967 of the Advanced User Guide: any button with a circle under it can be selected to centre the focus point, anything with a  - cannot.

[ebiggs1]

"Hoping that the community can clue me in on what I might be doing wrong!"

Yes hopefully we can.

 "Its not a fast focusing lens its known to be slow. "

First know the lens does not do the focusing. The camera does. So either you or the camera is not telling the lens when it is in focus or what it is focusing on. First I would reset your camera and after select just the center focus point and try it. Try not to be misled by confusing suggestions and keep it simple to begin with. As you said, "... Rebel Ti, and it works better there." A more simple camera.

[Waddizzle]

“ I recently picked up a used EF 85mm 1.2 L II to use primarily on my R6 mk2. I've found that it tends to focus somewhere other than where I point it. When I use Spot or 1-Point AF, it seems to be looking around to find maybe the closest object, or maybe the highest-contrast object rather than what I have the focus point aimed at. It doesn't matter how much light there is - this can be in broad daylight or in low light. “ 

Perhaps you have misspoken.  As has already been noted, lenses do not decide where to focus.  Lenses are controlled by cameras, and cameras are controlled by the photographer.  

What other lenses do you use with the R6 mark II?  Do you have any focusing issues with them?

What are you trying to focus on?  Are you using One Shot drive mode or Continuous Shooting drive mode?  The EF 85mm f/1.2L II USM is not a fast focusing lens.  It is not compatible with the high frame rates the camera is capable of using.  The lens sacrifices focusing speed for focusing accuracy.

The advanced subject tracking features almost demand fast focusing lenses.  The lens is also probably not fully compatible with the advanced tracking features of the R6 mark II, either.  

The Rebel camera body does not focus very quickly.  So, the lens may feel right at home on the older Rebel body.  

[Waddizzle]

“ As an example, taking a picture of a plant pot - I put the AF mark on the leaf or bloom that I would like in-focus, but the camera focuses on another leaf or bloom. I've tried opening up the AF options to larger areas, and that just broadens where it looks... and rarely focuses on what I intend. My expectation with Spot or 1-Point AF is for the camera to focus on that spot each and every time, assuming there is adequate light, which there is. “

This sounds like a potential depth of field issue.  How close to the flower are you?  What aperture setting are you using?  Your description sounds like it has the potential to be a macro photography scenario.  

During macro photography, the depth of field can be significantly less than an inch.  If you are shooting handheld, then it is absolutely VITAL that you do not move after the camera has locked focus.  If not, the focus plane may move before the shutter fires and your focus may seem to have locked on elsewhere.

[mattplatts]

Thank you for the thoughtful replies. Several questions were asked, so let me try to clarify my "use case" to help narrow down what's happening. I'm in the back yard, aiming at and attempting to focus on individual objects to confirm operation. For these tests, I am not trying to make quick shots - I am being careful to not exceed the capability of the lens focus type/motor... this is non-moving, no-action shots of static objects like plants just because I have several to pick from as I walk around. In the "old days" with an SLR, I would be able to pick one particular leaf on a plant, focus (with back button) on that leaf, and then snap a picture.

Since reading and re-reading these replies, it did occur to me that I've blamed the lens when the issue may really be the camera or my expectations. I've confirmed that this morning while testing the same scenario with other lenses like the RF 28-105 F4 L and my old EF 70-200 F2.8 L. Both act the same unfortunately :-(.

A simple example that may help to explain my frustration is this: I'm standing on my lawn and aim the center focus point at grass that is 10' away, then 20' away, and then 30' away, pressing by BBF button each time. And each time, instead of focusing at the spot (or dance/plane) that I've selected, the camera picks another area of the lawn or maybe a fence in the distance (40-50' away). Do I have an unrealistic expectation of being able to focus within the plane that I've aimed the center focus point at?

Additional settings details:

Back-button focus is exclusively used
AF Area = Spot or 1-Point AF
AF Operation = One Shot
Drive Mode = Single Shooting
Subject to Detect = None or Auto (both tested)
Aperture is set to 1.2 (M or Av, both tested)
Object distance while testing is generally 10-40', sometimes closer but limited by minimum focus distance of the lens.

Again, thank you for helping me to sort this out! At this point, I'm just trying to confirm whether or not my gear is working correctly, or if my expectations for this lens/camera combo need to be reset. Maybe true “single point focus” is gone… but I hope not. I enjoyed the days of being able to put the center point on someone’s eye, focus, recompose/reframe, and then take my shot.

[Tronhard]

As I have written I use single point focus and I do so via the back button too.  I have explained that the focusing system, by default, seeks the closest object, single-point or otherwise.   Particularly with single point, it doesn't know what you want to focus on, so you direct it with the centre focus feature that I have explained the use of and shown you how to assign it to a convenient button.   I would encourage you to try it.
So, my sequence would be:
1. Point the centre of the viewfinder at the point you want in focus and press the centre focus location button
2. tap the back button focus and sort out your exposure, if necessary
3. Recompose and shoot.

[deebatman316]

The camera will ALWAYS focus on the closest thing to it. You must intervene and tell the camera what you want it to focus on. The camera doesn't know what you want to focus on. Also why are you shooting at F/1.2 that will cause the picture to have a lot of bokeh. This will also make it seem that the picture isn't in focus but it is. F/1.2 has paper thin depth of field. So please take @Tronhard's advice. An SLR or DSLR camera will act the same way if you don't tell the camera what to do. It will also focus on the thing closest to the camera. There's no avoiding this unless you tell the camera what to focus on. 

Gear: EOS 40D, EF 50mm F/1.8 STM, Settings: Tv 1/1000th, Av F/1.8, ISO 100EOS 40D Sigma 17-50mm F/2.8 EX DC OS HSM @ 50mm F/2.8Gear: EOS 5D Mark IV, EF 85mm F/1.8 USM, Speedlite 470EX-AI Settings: Tv 1/1250th sec, Av F/1.8, ISO 400, High Speed Sync Flash

[wq9nsc]

So when you are looking through the viewfinder, is the selected focus point staying in one spot where you selected or is it moving around?  When you look at the image in DPP, where does it show the focus point (where you selected or on the point actually in focus)?

I really like my 85 f1.2, it certainly doesn't focus quickly like my other glass but nothing is better at making the background fade away into blur 🙂

It shouldn't matter whether DSLR or mirrorless, if you select a specific single focus point and have that on a specific item in the scene then it should focus on that point if focus is possible.  It should definitely not be focusing on some random part of the scene just because it is closer if you have selected a single focus point.

Rodger