I'm having trouble nailing focus on canon EF 85mm F1.2 on my canon 6Dmk i

I have dreamt of owning this lens for a very long time and I finally bought one last year summer. I have problem nailing focus on this lense at f1.2 and even at f2, I still have lots of OOF shots

I wish anybody can help me on technique on how to use this lens

When it nailed focus, its absolutely phenomenal

Thanks in advance

I had that same combination. Love the lens, but if you're using anything other than the center focus point with that camera, getting stuff in focus will be a crap shoot.

First post! Welcome to POTN.

For any focus issues people will ask to see some examples.
You can post 2 images in a post if you upload or 8 if you embed, ie use a hosting site.

Obvious questions will be:
Are you familiar with MFA? (Micro focus adjustment)
As already mentioned, are you aware centre AF point on 6D is very good but others are not?
Have you determined if focus is off in the same direction? ie, front focused or back focused.
Do you get bad focus for stationary subjects or are they moving?
Are you sure it is focus error, not movement of either subject or camera? If something in the shot is in focus but not where you placed the AF point that indicates focus error.
Is your shutter speed high enough?

Testing is easy.
My EF 85 1.8 @ f2.
Centre focus point put on the bar code.

Notice shutter speed 1/4000 sec.
Notice also that I would call this a good result.
Look at the inch scale on the ruler. 22 is on the same plane as the bar code. 22 and 23 about the same sharpness.
21 and 24 also show similar softening. 20 and 25 also similar, 25 slightly better.
Because of slight parallax, I was shooting down at an angle, the barcode is actually slightly closer to the camera than 22 on the ruler. So the fact that 22 and 23 are about equally sharp makes sense.

I know I can put my lens on the camera and get good results. This test took a couple of minutes.
If I was having problems I would spend more time and use some different subjects. I'd elevate the ruler so it was more accurately on the same plane as the barcode.

It sounds like you need to micro adjust your focus. See page 314 of your owners manual to see the menu options to do this. Canon 6D Manual.

I have always done the adjustments using the dot tune method, but there are other methods as well.

Thanks for the uploaded images

How did u place the box and the ruler on the floor? Does it have to be an exact way of placing them to get accurate result?

The 85/1.2v1 and 2 are not AF friendly and challenging to focus manually wide open. The DOF is so thin when shot wide open that it’s easy to miss focus. I think that you compound the errors when shot on anything other than a 1Series or 5D body. As suggested, a micro adjustment may improve your keepers.

Charlesmyd wrote in post #19032358
Thanks for the uploaded images
How did u place the box and the ruler on the floor? Does it have to be an exact way of placing them to get accurate result?

Place it anywhere. I used a typical distance used for half body portrait.
You are testing the AF of the camera and lens combination, that's what you hope is accurate.
That was just a convenient subject, the barcode is a high contrast subject for the camera/lens to easily focus on.
Without the ruler, the tiles on the ground show where focus was, the ruler just makes it much easier to see.

I did keep the box square to me.

Use some basic logic. If it was a new lens and I was about to shoot some portraits, that test would have been perfect.
If I was going to be shooting some group portraits, I would have placed the box at approximate distance that I would be shooting the group, but then the box and barcode would probably be a bit small so I'd use a different subject.

If I was just using the lens for hobby use, I'd just use the lens and only do testing if I was not getting good results.

tcphoto1 wrote in post #19032387
The 85/1.2v1 and 2 are not AF friendly and challenging to focus manually wide open. The DOF is so thin when shot wide open that it’s easy to miss focus. I think that you compound the errors when shot on anything other than a 1Series or 5D body. As suggested, a micro adjustment may improve your keepers.

OP said problems also at f2. While Depth of Field is still small at f2, on 6D using centre AF point, good results should be easy.
6D centrepoint is just plain good. It is comparable to 1 Series or 5 Series.
The other 8 AF points on 6D are definitely poor.

I own this lens and get very sharp results at all f-stops. However, I have no experience with the 6D. Your post didn’t mention if you have the ver1 or ver2 of this lens. AFAIK, the ver2 has a bit better IQ. Read the review on TDP. The review should say the differences between the versions.

At f1.2, the depth of field is razor thin. Any camera movement will result in OOF shots. This lens is heavy but balanced and using a higher shutter speed is a must unless you use a tripod. Focus and recompose at f1.2 is also challenging. I don’t use focus and recompose on any of my lenses. Also avoid protection filters shooting at f1.2. The only filter I use is a polarizer. In addition, shooting at f1.2 in servo using bbf is a crap shot when nailing focus. I’m sure there are lots of people who use servo for everything but I use one-shot with confirmation and get very good results. This lens is a portrait lens. The new f1.4 is the better lens for quick shooting IMHO, YMMV.

My copy is very sharp. Maybe I just lucked out when I bought it. If you purchase this lens used, making sure the lens was not dropped before buying. A dropped 85L II may also affect IQ. This lens and the 50 f1.2 are on my buy new lens list.

Hope this helps.

I was thinking of buying canon 5d mkiii. What do you think about the autofocus on that with canon 85mm f1.2L ii?

Seriously, you should try, if you have that opportunity, an EOS R or EOS RP with that lens.

I was stunned when I did, focus is nailed every time, no adjustments necessary. And it focuses a bit faster too. Any errors in focusing are user error, certainly with the EOS R.

I was so impressed that I actually got the RF version of this lens as well. Just to be stunned even more .

HTH, kind regards, Wim