# Is it really that hard to autofocus on apertures larger than f/2.5?



## Mancubus (Jun 15, 2015)

I consider myself an experienced photographer, currently on my 4th DSLR (600D, 70D, 7Dm2, 5dm3). I've been taking photos professionally for some time and I am always improving in any areas that I think I can improve at.

But I can not trust any shots taken with aperture larger than f/2.8 (let's say from 1.8 to 2.2 mostly). No matter what technique I use, even on controlled conditions shooting high contrast targets, I can't get tack sharp focus in more than 70% of the shots.

I've had the 50mm 1.8 II, 2 copies of the 85mm 1.8 and now the new 50mm 1.8 STM, which according to reviews has very accurate autofocus. And with 4 different lenses and 4 different bodies, I could not get a combination that gets reliable (>90% in focus) results. I actually get around 70% in useable focus, and the others are a bit front or back focused (never in just one direction).

I would like to believe I am doing something wrong, but I can't see anymore flaws with my technique. Sufficiently high shutter speed, proper lighting, center point high precision AF, no shaking, no recomposing and I still have to rely on luck to get a tack sharp shot.

The 5dm3 (my best performer) with the new 50mm 1.8 STM in test shots at 1.8 is giving me about 70% shots in acceptable focus, 25% a bit off and 5% way off. When shooting portraits at f/2.2 for example, I take 3 shots refocusing in each of them so I am almost guaranteed to have one that is properly focused. 

MFA was almost useless in any of my bodies and lenses, because when the focus is missed, it does not happen in one constant way, it is always randomly off to the front or back. 

Now here is my big question: am I worrying too much? are all these lenses and bodies working properly and it's just me having too high expectations? Is 70% of 1.8 shots in focus acceptable?

I simply can't believe that I have 4 faulty bodies or 4 faulty lenses. But on the other hand, some reviews that I read lead me to think that with a properly working body/lens, the center AF point on a stationary target is almost guaranteed to nail the focus.


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## NWPhil (Jun 15, 2015)

you are not saying what kind of subjects and/or photography field you having trouble with, neither lens used - better yet, posting examples.

Also mention if you have done any lens AFMA and if used live view to focusing. Details like using the tripod and locking the mirror, and using delayed shutter might help too figuring out the issue(s)

in sum, provide specific details and back it up with pictures.

then will be easier to get help and advice from expert people 

ps: yes it can be difficult, as the DOF becomes very narrow


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## Don Haines (Jun 15, 2015)

Step one is always to AFMA your lenses. Your camera and lenses are a complex system and without basic calibration you will have an almost impossible task to figure out what is wrong.....

FYI, last month we got in a $140,000 piece of test equipment at work...... we spent 2 weeks calibrating it. Without the calibration it would have been worthless.


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## Mancubus (Jun 15, 2015)

Don Haines said:



> Step one is always to AFMA your lenses. Your camera and lenses are a complex system and without basic calibration you will have an almost impossible task to figure out what is wrong.....
> 
> FYI, last month we got in a $140,000 piece of test equipment at work...... we spent 2 weeks calibrating it. Without the calibration it would have been worthless.





NWPhil said:


> you are not saying what kind of subjects and/or photography field you having trouble with, neither lens used - better yet, posting examples.
> 
> Also mention if you have done any lens AFMA and if used live view to focusing. Details like using the tripod and locking the mirror, and using delayed shutter might help too figuring out the issue(s)
> 
> ...



I will try to recreate some test and post the results here. 

Currently I'm with the 5dm3 trying to get the best of the 50mm 1.8 STM. Live view surely gives me better results, but it's no use to me, I need to achieve good focus by using the viewfinder.

As I said AFMA is not useful at all to me, because the focus does not miss in a constant way. What good is AFMA when 40% of my missed shots are front focused and 60% are back focused? 

I know how to do AFMA, my 100mm macro 2.8 was always  back focusing a little on my 7Dm2 before, so by trial and error I got the calibration value (-5) that made this lens (100mm macro) to focus properly. However, this is *not *the case with the 1.8 (all 50mm and 85mm) lenses, as the focus error is not constant in intensity not back/front direction. There is no AFMA on these 1.8 lenses that will give me consistent good results.


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## agierke (Jun 15, 2015)

i have never been impressed with the 85mm 1.8 as i have found its autofocus characteristics to be unreliable and erratic. sometimes it hits...sometimes its way off even though i get AF confirmation. using a 5d3 with it. because of this it is my least used lens.

cant speak to the new 50mm 1.8 STM as i have yet to use it...and probably never will to be honest. i have the 50mm 1.8 v2 but never really liked that lens either. it was neat in the beginning shooting wide open with it but i ended up disliking the slow and noisy focus and the colors and rendering of that lens were just unappealing to me. haven't used it in years.

i do own the 35mm 1.4 and the 50mm 1.2 however and i typically shoot those lenses at or around F2. i have found my 35L to be a superb performer in terms of AF around F2. it does get a touch soft wide open so i hardly ever push it that far. i use the 50mm 1.2 a bit less than the 35mm but i haven't noticed any issues AFing at around F2. 

you have to remember that the type of lens used can be just as big of a factor in getting reliable AF as the type of body/focus system used...regardless of AFMA. i am not surprised at all that you are finding issues with the 85mm 1.8 and 50mm 1.8 II....they are kinda dogs in my book.


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## meywd (Jun 15, 2015)

One thing to make sure of, are you doing the tests in good light? low ISO or high ISO? the 50mm 1.8 II is soft wide open, more so on high ISO even on the 5D III, and in low light the AF is not good.


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## Mt Spokane Photography (Jun 15, 2015)

Generally, if you do not get sharp focus at wide apertures, something is wrong. It can mean AFMA is needed, or the lens or the camera has a issue.

Not all lenses are sharpest at wide apertures, but the 85mm f/1.8 is very good wide open.


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## mistaspeedy (Jun 16, 2015)

The 50mm F1.8 II lenses are absolutely terrible as far as autofocus accuracy/consistency is concerned... forget they exist and don't include this ultra-cheap one-off lens by Canon. (it is not representative of all the other lenses Canon makes). Nearly everyone with this lens seems to agree on this, and I have personally experienced this when using this lens.

lensrentals did a whole series of articles about autofocus accuracy... in short, newer bodies combined with newer lenses gave more accurate results... but you needed BOTH for this to be true. (new means about 2010-2012 and newer)
http://www.lensrentals.com/blog/2012/07/autofocus-reality-part-1-center-point-single-shot-accuracy
^read all the articles, it will answer many questions about autofocus... which lenses, which bodies, which autofocus modes (phase detection, contrast detection and manual focus via live view).

I don't know much about the 85mm F1.8 besides that it doesnt fall into the category of 'new' lenses that these articles talk about.

As far as the new 50mm F1.8 STM is concerned, reviews have found it to be a nice improvement over the older nifty fifty, and accurate in general.



> I can't get tack sharp focus in more than 70% of the shots.


Wide open aperture + focusing on something close is absolutely the hardest possible thing you can ask of your focusing system... a 70% hitrate is good.
Your 5D mark III is a new camera, and the 50mm STM is a new lens... combine them both for more accurate autofocus (more accurate than older body-lens combinations).

Also... the lenses you list aren't exactly top of the line (or new besides the STM) in any sense.
You have the cheapest of the cheap - 50mm F1.8 II (made back in 1990)
Then you have the old and cheaper 85mm F1.8 (made in 1992)
and now the cheapest (but new) 50mm F1.8 STM

So we don't really have any new and wide aperture lenses for Canon besides the 50mm STM that was just released and the 35mm F2 IS << this is the lens I would compare autofocus accuracy with, since it is a new lens with a USM focus motor - but it is in a higher price range.


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## eninja (Jun 24, 2015)

You need to find the love to AFMA.
When doing manual AFMA (not using FoCal). You need to observe the photo that the subject is in the center of front blur and back equal blur area.
My 6D with 50L focus accurately at F1.2 even.


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## Sporgon (Jun 24, 2015)

I'm not at all convinced that the actual mechanical gearing of lenses such as the 85 f/1.8 are capable of repeating 100% accurate focus at f/1.8 on a close target. I seem to remember that Roger at Lens Rentals wrote something about lenses such as the 85/1.8 just not being able to mechanically match the (then new) cameras such as the 5DIII.

Unfortunately it appears that it you really must have that sort of precision and accuracy you have to look up market.


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## mistaspeedy (Jun 24, 2015)

As I mentioned in my previous post, but I will repeat using slighting different words:

Canon has improved autofocus accuracy in recent years, but it took a redesign of BOTH LENSES AND CAMERAS to actually get this improved accuracy (with phase detection autofocus)

old camera + old lens = standard accuracy
old camera + new lens = standard accuracy
new camera + old lens = standard accuracy
new camera + new lens = improved accuracy

Canon 5D mark III (new camera with latest autofocus) + Canon 85mm F1.8 (old lens from 1992)


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## atkinsonphoto (Jun 24, 2015)

I tend to shift to single point auto-focus when the apertures get that wide. I've had good results from the 85 1.8 and and the 35 2 IS.


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## e17paul (Jun 24, 2015)

mistaspeedy said:


> The 50mm F1.8 II lenses are absolutely terrible as far as autofocus accuracy/consistency is concerned... forget they exist and don't include this ultra-cheap one-off lens by Canon. (it is not representative of all the other lenses Canon makes). Nearly everyone with this lens seems to agree on this, and I have personally experienced this when using this lens.
> 
> lensrentals did a whole series of articles about autofocus accuracy... in short, newer bodies combined with newer lenses gave more accurate results... but you needed BOTH for this to be true. (new means about 2010-2012 and newer)
> http://www.lensrentals.com/blog/2012/07/autofocus-reality-part-1-center-point-single-shot-accuracy
> ...



My 1987 design (but new in 2013) 50/2.5 compact macro autofocuses better on my 90s Eos film bodies than my modern day 6D. I'm sure its not a case of the older camera having better AF, but Canon optimising certain combinations better than others.


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## surapon (Jun 24, 2015)

Mancubus said:


> I consider myself an experienced photographer, currently on my 4th DSLR (600D, 70D, 7Dm2, 5dm3). I've been taking photos professionally for some time and I am always improving in any areas that I think I can improve at.
> 
> But I can not trust any shots taken with aperture larger than f/2.8 (let's say from 1.8 to 2.2 mostly). No matter what technique I use, even on controlled conditions shooting high contrast targets, I can't get tack sharp focus in more than 70% of the shots.
> 
> ...




Dear Friend Mr. Mancubus.
The Auto Focus of every Lenses/ Cameras in this world ARE DEPEND ON THE LIGHT AT THE SUBJECTS , The Movement AND THE TONE CONTRAST OF THE SUBJECTS. 
I use Film Camera First Canon Auto-Focus in 1982( FT-QL( 1956), T-50, T-70, T-90, EOS-A2E), And Use Auto-focus of DSLR in 1999----I have no Problems of Auto focus at all ( my DSLR Olympus C2500L, Canon 20 D, 1DS, 5D MK II , 7D, E0s-M and 7D MK II, with 19 Canon Lens , 1 Sigma Lens, 3 Temron Lens, 1 Vivitar 28-70 Auto focus Lens)----
BUT, my trick is When Bad light/ Dark shade area( Plus 80% of my Portrait photos), I USE ONE CENTER SPOT AUTO-FOCUS WITH THE BEEP SOUND , Plus in the dark area, I use Canon Flashes 580 EX II / IR. light to guild my AF. spots. 
If I do not use Flash in the Shade area or dark area to get natural Light photos, I use Canon speedlite-Transmitter ST-E2, with built-in AF- assist beam to emitted automatically to make it easier to autofocus.

Good Luck and have a great day.
Surapon

PS. This morning, Before I answer your Post, I use my Canon 5D MK II with Canon EF 85 mm f/ 1.8, and Canon EF 85 mm. F/ 1.2 L MK II to use Multi-Spots AF( Medium slow AF. in the shade with no contrast area). and Single spot AF.( Super fast AF. in all area) with no problem at all = 100 % corrected AF.


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## Luds34 (Jun 24, 2015)

First, I agree with everyone on the old nifty fifty (I'd argue you can apply it to the EF 50mm f/1.4 as well). That lens is just not consistent so no AFMA will ever save you there. I owned one for a brief time (less then a year) and was first to fault the user (me) and not the tool. But eventually I realized the limitations of that lens at wide apertures.

Now, for the new 50mm STM? I'd be surprised if that is not spot on (I mean consistent). My experiences and understanding, talking with fellow shooters, reading on the interwebs (gasp) is that all of the latest lenses from Canon have "just worked". All the STMs are new designs and I have experience with about 5 of their models, from pancakes to the kit zooms, and the focus is always really spot (of course these are not the widest aperture lenses).

As for the 85mm f/1.8. Again, I'm just one data point, these are my anecdotal stories, etc. But I have this working theory, that even the old lens designs if they were recently manufactured (say the past 5 years) are going to be just as good as any of the new designs. Whether it is better manufacturing tolerances, updated electronics, or updated firmware (probably a combo of all 3), these lenses perform very well.

I have a 28mm f/1.8 and 85mm f/1.8 purchased new in the past few years. Each of them are spot on with their focus all the time. I've tried to AFMA both of them on my 70D and I ended up at zero (Haven't even bothered with the 6D since they continue to just "hit" and another lens I owned AFMA'd to the same setting on both bodies). The one time I ran tests and did the pixel peeping that I thought needed adjustment (comparing the live view vs PD shots) it turned out my issue was lighting my subject exclusively with a bunch of CFLs. When I repeated the test with natural light, that slight bit of being off disappeared. And when I mean off, it was slight, I could only could really tell by seeing a bit of purple fringing.

I guess I am surprised to hear that you can't get consistent results with any of your lenses based on what you have in your kit. I understand being consistently off and having to AFMA, but not what you are seeing.

I don't like to do these tests, it's a pain, etc. etc. But have you taken the time to do the who spiel, with mounting on a tripod, a static subject, pre focusing the lens to nearest focus, then focus/shoot. Pre focus to infinity, focus/shoot. Repeat these same tests, but with live view. Then repeat the whole set of test a few times and the go through and compare the live view with the PDAF. It's a pain to do, but I've sat there with a notepad and after each shot, I'm checking columns of if the shot was live view, was the prefocus near or far, the distance from subject, etc. etc. So that when I unload all the photos and start pixel peeping in LR on a big screen I have a reference for all the shots.

Because, if all of your lenses (not just the old nifty fifty) can not produce consistent focus (even if it is consistently front or back focuses) then something is really wrong. Maybe the camera body?


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## Mt Spokane Photography (Jun 24, 2015)

Sporgon said:


> I'm not at all convinced that the actual mechanical gearing of lenses such as the 85 f/1.8 are capable of repeating 100% accurate focus at f/1.8 on a close target. I seem to remember that Roger at Lens Rentals wrote something about lenses such as the 85/1.8 just not being able to mechanically match the (then new) cameras such as the 5DIII.
> 
> Unfortunately it appears that it you really must have that sort of precision and accuracy you have to look up market.



Except for Macro lenses, most lenses struggle near MFD, I'm not sure that any are consistent at MFD either. Some, however are better than others, its a function of the lens design so YMMV.

My 24-70mm MK II is weaker at MFD. My 24-105mm L was reasonably good at MFD.


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## drmikeinpdx (Jun 25, 2015)

Mancubus, I feel your pain! But we could help you better if you would give us more information. In particular, what kind of subjects are you shooting? Sports? Macro? Crazy kids in the back yard? 

FWIW, my 5D3 makes all my troublesome old non-L lenses focus very nicely, although not as super-precise as the L lenses. Maybe you should borrow or rent a large aperture L lens and do some focus tests.


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