Canon 70d Focus Issue - Am I going mad?

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Rich Perkins
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Hello All,

My Canon 70d has started with what seems to me, a focus issue. Most of my recent photo's appear to be out of focus ever so slightly. The camera is around 14 months old but I have a 2 year warranty from the supplying shop. Sent the camera off to the supplying shop and the camera was sent to Cannon where the only issue found was with the calibration. I quote - "They [Canon] have calibrated the camera autofocus to specification and have also calibrated the lens’s focusing unit to specification."

Got the Camera back yesterday and the kit lens has a micro adjustment W +2 (adjust by lens). I can't see any other changes to settings. According to the shop, the autofocus points can be calibrated by anyone, although a google search has only brought up micro adjustment - is there another focus calibration setting for the 70d? Call me sceptical, but feel like I've been mugged off by Canon.

Anyway, I've tested the camera today where it still seems off. I have a calibration card. I've set it up in a fixed location, single centre point AF, used a prime lens (so I don't have to worry about zoom), on a sturdy tripod with a remote and delayed shutter. I'm seeing inconsistent results. These 6 images were literally taken shot after shot, looks to me like I have a +/- 3 variation.

IMG_9678.jpg by Rich Perkins, on Flickr
IMG_9677.jpg by Rich Perkins, on Flickr
IMG_9676.jpg by Rich Perkins, on Flickr
IMG_9675.jpg by Rich Perkins, on Flickr
IMG_9674.jpg by Rich Perkins, on Flickr
IMG_9673.jpg by Rich Perkins, on Flickr

Is what I'm seeing normal or a potential issue? This to me doesn't seem right - If i'm getting 3cm focus differences on a tripod, I have no chance of getting anything whilst on the move.

Any advice or pointers to put me on the right track please?
 
The EF 50/1.4 has imprecise AF and will not land you at the same spot every time. The camera could be the finest on earth, but the lens has to focus to where the camera tells it. I stop mine down to around f/2 or smaller in order to avoid such frustrations. It sharpens up the IQ as well as providing some breathing space for focus errors. To try to improve consistency defocus the lens a little beyond the subject and then have the camera pull focus back to the subject.
 
Thanks for your response. I had another play this morning following canons microadjustment guide perfectly.

At the recommended 2.5m - My tool is too small so accuracy is a no no. at 1m (same as the tests above) I can pin point more.

The only thing I wasn't doing on my old tests was re-setting the focus so the camera had to re-focus each time. That's made a difference with my tests. This time I've come to set the microadjustment at -3 for this lens. When taking a set of six I've moved to focus ring backwards and forwards between each shot (so the focus either has to pull back or forward).

I've noticed if the focus starts behind my target, the focus settles ever so slightly behind after autofocus. If the focus starts in front of my target, the focus point is ever so slightly in front after auto focus. Basically it looks like you're right and the lens isn't perfect so can't reach the desired focus point the camera is telling it. There is still variation but I've come to the conclusion this is the best i'll get but variation is so small it shouldn't be an issue. I've settled on +/- 1 now. I'll take that.

However, something still isn't right. Live view is taking great shots. Same shot, tripod and same setting with the view finder and focus is still out. I took x4 shots, all re-focusing each time. Live view perfect 4/4. Viewfinder 0/4.

E.g:
IMG_9793 by Rich Perkins, on Flickr
IMG_9789 by Rich Perkins, on Flickr

Look at the little metal pins and ring at the top.

It's so minor, but something isn't right. Thoughts?
 
Thanks Chaps.

I'll look over the links :)

I've read about the wide open faults and AF issues on some apparent batches (if the internet is to be believed). My camera performed perfect for 12 months. Then something has deteriorated. I've checked shutter count and it's 3,588 (I bet a chunk of these is test shots for this issue). It's nothing for one of these.

Forgive me if i'm telling grandma how to suck eggs, i' just going over my thought process with you guys. Basically, this camera has 19 AF Points but I always use the centre weighted 6 point multi-focus (the six centre points, imagine 3x3 squares). The camera will then choose the optimum focus point(s) to use from these 6 - It can use all 6 or just 1, depending on the subject. I found using the whole 19 AF not accurate enough and if I reduce the points any less, far too accurate (such as focusing on a nose rather than face as an example). I have used these 6 focus points since very early on in the camera ownership whereby the first 12 months use were perfect - Up until recently I'd have expected no less of a result than what i'm only seeing in LiveView now - Something has deteriorated.

When selecting x1 specific AF Point things seem much better (although too accurate for my liking). Live view uses it's own AF system. So to me, this would suggest the camera appears to be having trouble selecting the correct points when faced with the option of more than one AF point, when using the view finder.

I have noticed (unsure if it's me being over sensitive) when using these 6 points, the camera is reluctant to use the top three. Possibly the viewfinder AF system is screwed so the camera simply can't detect what it should be focusing on properly.

I also took the same shot as above with the kit lens (18-135mm) earlier with very, very similar results. To confirm, this lens and all focus settings are as Cannon sent back to me. The issue is not as bad, but it's still there (look at the metal ring at the top of the fitting). I feel Microadjustment is just masking an underlying issue with the AF system.

IMG_9807 by Rich Perkins, on Flickr
IMG_9803 by Rich Perkins, on Flickr

Tell me i'm not seeing a focus issue here.
 
It is odd to hear a complaint of AF which is "too accurate". If you want the best results YOU should be picking the most suitable AF point and placing it exactly over the part of the subject which you want to be sharp. If you want the eye to be sharp instead of the nose then place THE AF point over the eye, not a bunch of them vaguely in the direction of the face. I don't have a 70D, but there are two configurations of the nine AF point scenario. One uses the centre point of the nine as the pirmary point and only falls back to the others if it can't find anything to focus on at the centre. The alternative configuration treats all nine points equally and the camera will pick the one which has the closest focusable thing behind it - e.g. the tip of a nose instead of the eye, or the eyelashes instead of the eyeball. Either way, the camera is making selections for you and, unless, or even if you know how these things work, it may not give the result you want.

On top of all this, the centre AF point is the most sensitive and accurate and when you microadjust you usually do so for this point. But that should not be taken to imply that all other AF points require the exact same amount of microadjustment, so once you (or the camera) chooses an alternate point the results might go down hill. For moving subjects such as birds in flight or running dogs you might well find multiple active AF points to be a necessary evil. Even then, the fewer you can get away with the better. But if you are shooting a static subject, whatever it may be, then one point placed where you want it is the best way to go. If you do use the centre point and recompose then be aware that your focus distance will probably change as you recompose, so this technique can appear to give focus problems at large apertures and short distances.
 
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FWIW those shiny light shades are not a good way to test autofocus. Your camera won't 'know' whether you're trying to focus on the shade's surface or the reflections- two very different points of focus.
 
And remember that the actual size of each AF point is larger than the little squares in the viewfinder and may not be lined up precisely with them, so the AF system might latch onto something which is outside the AF box rather than within it. So in the example shown the camera could switch between the actual lamp shade or the reflection depending upon exactly where you aim the AF point. Definitely a poor subject choice for AF testing.
 
Thanks Chaps, your advice is very much appreciated. :ty:

Ok, so my terminology on AF isn't the best. Too accurate was probably the wrong wording. Too focused? Pin pointed? I like to shoot wide open so if I shoot single point I get a tighter focus range. I've always had better results using the multi focus set to the centre 6. I always re-focus a couple of time to ensure the Multi-AF is pointing where I want it on the subject. My method hasn't changed in over 12 months, Hardware hasn't. But my results have. I did think about settings, but I hadn't touched a thing. I've reset back to factory to be safe, and I hadn't touched MicroAdjustment once, only when the issue appeared did I start playing. I was at a wedding and literally half way through a set I saw the focus issue appear. I have 4 photo's I took one after another (literally click click click click) where you can see it got worse (it was early on so I wasn't drunk at this stage either! :LOL:). I'll try dig them out.

I have taken on board that the bulb/shade wasn't the best test subject due to the reflections. So here we go, new test subject; this ones a little more life like. Hand held, point and shoot, same settings. Just to be more realistic with the fault - As i'd find it in real world scenarios. Same issue. Single Point good, Live View good, Multi AF bobbar (for you Yorkshire men out their).

Harry Multi Point AF by Rich Perkins, on Flickr
Harry Single Point AF by Rich Perkins, on Flickr
Harry Live View by Rich Perkins, on Flickr

Harry Multi Point AF II by Rich Perkins, on Flickr
Harry Single Point AF II by Rich Perkins, on Flickr
Harry Live View II by Rich Perkins, on Flickr

Best way to describe what i'm seeing, looks like I'm seeing Multi AF shots with sleep in my eyes. This isn't right, I've had nice results before with wider apertures. E.g:

IMG_1734.jpg by Rich Perkins, on Flickr
 
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Multiple AF points is OK for subjects that are prone to move about and will therefore shift out of your chosen point.

But as others have said, it's just the wrong technique for static shooting. You should always choose your focus point, don't ever expect a camera to guess what you want to focus on.

This is the most PICNIC issue I've seen a complaint about.

(From my time in IT support; Problem In Chair Not In Computer).
 
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Phil V said:
Multiple AF points is OK for subjects that are prone to move about and will therefore shift out of your chosen point.

But as others have said, it's just the wrong technique for static shooting. You should always choose your focus point, don't ever expect a camera to guess what you want to focus on.

This is the most PICNIC issue I've seen a complaint about.

(From my time in IT support; Problem In Chair Not In Computer).
Click to expand...

Forgive my ignorance, but what's PICNIC?

I appreciate and taking on board that my technique appears to be wrong. But as I say, my technique hasn't changed. Are you suggesting that after 12 months my cameras giving me the fingers and telling me to change technique? :naughty:

Ahhh. PICNIC. I get it. Typical IT Support response. IF the issue was always apparent, fair enough, but the issue arose after 12 months with the same user error, explain that one.
 
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EnthusiastOwned™ said:
Forgive my ignorance, but what's PICNIC?

I appreciate and taking on board that my technique appears to be wrong. But as I say, my technique hasn't changed. Are you suggesting that after 12 months my cameras giving me the fingers and telling me to change technique? :naughty:
Click to expand...
I gave the definition in my post.

I'm not suggesting anything other than it's completely inconsistent.
I can't say why it appeared to be more consistent in the past. But it's still a stupid thing to do. :)
 
Phil V said:
I gave the definition in my post.

I'm not suggesting anything other than it's completely inconsistent.
I can't say why it appeared to be more consistent in the past. But it's still a stupid thing to do. :)
Click to expand...

Fair enough. My technique will change and improve now I know. Still doesn't explain why it's suddenly gone from usable to useless in the click of a button (excuse the pun). There is an underlying fault, regardless of my technique.
 
No, it didn't explain the sudden change in behaviour, but a knock to the equipment might. The 50/1.4 is prone to AF damage if the lens is at all extended and receives pressure or a knock to the front. This can be mitigated with a lens hood and/or storing/transporting the lens (including when walking about with it) at its shortest length.
 
tdodd said:
No, it didn't explain the sudden change in behaviour, but a knock to the equipment might. The 50/1.4 is prone to AF damage if the lens is at all extended and receives pressure or a knock to the front. This can be mitigated with a lens hood and/or storing/transporting the lens (including when walking about with it) at its shortest length.
Click to expand...

Glad you said that. I did think it was the 50mm lens at first. I went into store where I bought it and showed the issue (John Lewis) who changed the lens for a brand new one (the week before I sent the camera back). No difference in the old and new lens. I think it may be the wider aperture extenuating the issue making it more apparent with this lens.

I always transport in a Lowepro bag where the lenses are also wrapped in microfibres. I'm OCD anal, it's not taken a knock that i'm aware of. Plus, wouldn't have Canon picked up on it, no way would they do any warranty work with a knock? The issue is apparent with the Kit lens too (dog photo's above).

So just to confirm where we are. My technique needs improvement, but there is a fault, right?
 
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As far as I can tell in both the 42mm and 81mm sets of examples the worst shot is the one with multiple AF points enabled and front focusing seems to be the problem. There may be a problem with the camera and it might be with one or more of the non centre AF points. Inconsistency in results could be from inconsistency of AF point picked by the camera.
 
EnthusiastOwned™ said:
So just to confirm where we are. My technique needs improvement, but there is a fault, right?
Click to expand...

TBH there's no conclusive proof. The algorithm used by the camera to pick a focus point uses fuzzy logic and is completely unpredictable.

The only way to 'test' a lens accurately involves using a single focus point, why would you think that is?
 
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