80D Single-Point vs. 6D Single-Point?

[Cory]

With all this talk about the "inferior" 6D focus system does it really matter, for stills, if one uses just a single-point anyway? And, if so, is the center point generally "better" than the other single points?
THANKS.

 

[Loswr]

Short answer: it might matter and yes, the center point is better.

Long answer: not all AF points are created equal. The 6D's center point is a standard precision f/5.6 cross-type with an added high-precision f/2.8 horizontal AF line. Cameras like the 80D, 7DII, 5DIII/IV, 1D X/II have a dual-cross center point (f/5.6 cross with an added f/2.8 cross instead of just a line). If you only use lenses that are f/4 or slower, there's not going to be much difference with static subjects. But, if you have a fast lens you gain the advantage of higher focusing accuracy in multiple orientations with f/2.8 and faster lenses. If you're using fast primes wide open, using just the center point and recomposing to get a subject off-center (e.g. at a 'rule-of-thirds' intersection) will guarantee you a backfocused shot, that's just geometry at work and thus, with fast lenses you are better off selecting an AF point close to where you want the subject in the frame. With the 6D, that means you are using weaker AF points at the periphery.

 

[Mikehit]

No, it doesn't matter
Yes, the centre point is often better

 

[rfdesigner]

With all this talk about the "inferior" 6D focus system does it really matter, for stills, if one uses just a single-point anyway? And, if so, is the center point generally "better" than the other single points?
THANKS.

Center point is good, fast etc. yes double cross is better and the latest double cross is better still, but the 6D centre point is very good. The centre point is also good enough to AF on the brighter stars at F2.0 (been there done that)

The outer points on the 6D are simple single line, fine as supporting point with multi-point AF, and fine for relatively static subjects in moderate light, but they aren't a patch on the centre point.

 

[YuengLinger]

The 60D, except for the center point, has a better AF system than the 6D!

The 80D is way ahead of either, but why are you comparing a FF to a crop in your title? Just seems odd with the apparent differences in both focal lengths and the real differences image quality.

I think the AF point I use LEAST is the center point. (Ok, I'm sure there are extreme outer points that don't get used as often as, but, really, I rarely use the center point. Just too difficult to compensate AF correctly with a fast lens, as Neuro explained.)

People defend the 6D's AF, declare it fine, etc, but I thought the 5DIII AF was good. Then I tried the 5DIV.

Point being, we are happy with what we have until we try something better.

 

[hbr]

With all this talk about the "inferior" 6D focus system does it really matter, for stills, if one uses just a single-point anyway? And, if so, is the center point generally "better" than the other single points?
THANKS.

Hi Cory,

While I don't own the 80D, I do own both the 6D and the 7D II. The 80D's focusing system is vsry similar to the latter. With th 6D if your subject moves, you need to recompose then shoot vs the 7D's AF system will track the subject as it moves. So, two totally different AF systems.

The problem that I have with the 6D is that when I am photographing people or animals, the AF points do not spread far enough across the screen so I am either focusing on the navel or the chin of a person, but most often cannot focus on the eyes.

That being said, the 6D is still my go to camera. For landscape photography it delivers fantastic images and are much easier to clean up than the APS-C cameras. Definitely worth the money. especially at today's prices.

I believe both the 6D and the 80D;s AF center point will focus down to -3 ev which means the cameras will auto focus in almost complete darkness.

Brian

 

[hbr]

The 60D, except for the center point, has a better AF system than the 6D!

The 80D is way ahead of either, but why are you comparing a FF to a crop in your title? Just seems odd with the apparent differences in both focal lengths and the real differences image quality.

I think the AF point I use LEAST is the center point. (Ok, I'm sure there are extreme outer points that don't get used as often as, but, really, I rarely use the center point. Just too difficult to compensate AF correctly with a fast lens, as Neuro explained.)

People defend the 6D's AF, declare it fine, etc, but I thought the 5DIII AF was good. Then I tried the 5DIV.

Point being, we are happy with what we have until we try something better.

Hi YuengLinger,

You make an excellent point with one exception: unfortunately, some of us must settle with a Camry and can only drool about the Lexus.

Brian

 

[Cory]

Thanks all. Sounds like the 6D isn't terrible. Just put it through it's paces a bit at an orchestra performance on Sunday and got some spectacularly creative shots. The test will come with "running" events, but so far so good.
One thing I really do appreciate is the simplicity so there's that if all else fails and I just sort of feel slightly bad-a**ed with a full-frame camera. It's what'll tag along for the pending trip to Cinque Terre, Florence and Lake Como (from which, naturally, pictures posted here will follow).

 

[gruhl28]

Short answer: it might matter and yes, the center point is better.

Long answer: not all AF points are created equal. The 6D's center point is a standard precision f/5.6 cross-type with an added high-precision f/2.8 horizontal AF line. Cameras like the 80D, 7DII, 5DIII/IV, 1D X/II have a dual-cross center point (f/5.6 cross with an added f/2.8 cross instead of just a line). If you only use lenses that are f/4 or slower, there's not going to be much difference with static subjects. But, if you have a fast lens you gain the advantage of higher focusing accuracy in multiple orientations with f/2.8 and faster lenses. If you're using fast primes wide open, using just the center point and recomposing to get a subject off-center (e.g. at a 'rule-of-thirds' intersection) will guarantee you a backfocused shot, that's just geometry at work and thus, with fast lenses you are better off selecting an AF point close to where you want the subject in the frame. With the 6D, that means you are using weaker AF points at the periphery.

Hi Neuro,

Wouldn't using the center point and recomposing only guarantee a backfocused shot if the lens has a flat field? And don't many lenses not have flat fields?

I've read so much about outer focus points being less accurate than the center one, that I've always wondered whether using the center point and recomposing is more or less accurate than using an outer point might depend on the specific camera, the lens being used, and the distance to the subject. You have much more experience than I do; have you found that outer points are consistently more accurate than focus and recompose using the center point? Have you noticed differences depending on camera, lens, and distance?

 

[tcmatthews]

The 60D, except for the center point, has a better AF system than the 6D!

The 80D is way ahead of either, but why are you comparing a FF to a crop in your title? Just seems odd with the apparent differences in both focal lengths and the real differences image quality.

I think the AF point I use LEAST is the center point. (Ok, I'm sure there are extreme outer points that don't get used as often as, but, really, I rarely use the center point. Just too difficult to compensate AF correctly with a fast lens, as Neuro explained.)

People defend the 6D's AF, declare it fine, etc, but I thought the 5DIII AF was good. Then I tried the 5DIV.

Point being, we are happy with what we have until we try something better.

On paper. In practice I found the 6D out performed my 60D on just about every focus point. Focused faster and just as accurate. In end it the image quality was just plan better on the 6D. If the camera had a weakness it was in focus point spread, 1/4000 s shutter and no tilt screen.

 

[hgraf]

No, it doesn't matter

If you shoot with relatively bright lenses (say F/2.8 and brighter) it can matter alot.

https://digital-photography-school.com/the-problem-with-the-focus-recompose-method/

 

[Mt Spokane Photography]

Its difficult to compare AF between FF and APS-C cameras. There are too many varibles.

Typically, Canon AF systems are accurate to 1/3 DOF. This brings all sorts of calculations into determining which is the most accurate, but in the end, it sounds meaningless to me.

As a camera user for 60+ years, any of the AF systems are amazing when compared with old fixed focus, zone focus, ground glass TLR or range finder cameras I used. I think they all do a amazing job.

 

[Loswr]

Wouldn't using the center point and recomposing only guarantee a backfocused shot if the lens has a flat field? And don't many lenses not have flat fields?

While it's true that some lenses have field curvature, in practice for the majority of lenses that don't have a flat field, the curvature is in the wrong direction, i.e. it actually makes the focus-recompose problem worse. This diagram which I link from the photozone.de review of the 24-70/2.8L (MkI) is typical of lenses with some field curvature:

If you can picture this, imagine you've angled the camera in the diagram to focus using the center point (e.g. on a subjects eye away from the center of the frame) then moved the camera 'straight' so the focal point is now off-center. That results in back focus (you can see the link that hgraf provided for the geometry, of the blog post I usually link: Why Focus-Recompose Sucks). With typical field curvature, the more off-center your subject, the further out into the 'red zone' of the above diagram the you are...so you're adding the backfocus of focus-recompose to the backfocus of field curvature.

I've read so much about outer focus points being less accurate than the center one, that I've always wondered whether using the center point and recomposing is more or less accurate than using an outer point might depend on the specific camera, the lens being used, and the distance to the subject. You have much more experience than I do; have you found that outer points are consistently more accurate than focus and recompose using the center point? Have you noticed differences depending on camera, lens, and distance?

AF point performance is highly dependent on camera, lens, distance and most importantly the features of the subject (contrast and orientation). The problem with focus recompose isn't huge (it's not the difference between the face in focus or not, but rather, the difference between the eyelashes being in critical focus or being slightly soft and the earlobes being crisp). But, it's enough to ruin a shot, for me. But importantly, it's DoF dependent. If you're shooting at f/4 or f/5.6, in the example above both the eyes and the ears would likely be in focus. So the time to avoid focus recompose is with a fast prime shot at a wide aperture (e.g. f/2 or faster). The outer points are less precise and less accurate than the center point, but a highly accurate center-point focus with a guaranteed backfocus from recomposing means almost every shot like that will be for the bin. A less accurate and precise off-center point, and taking a burst of 3 shots, means I am almost always guaranteed a keeper.

 

[hbr]

Thanks for explaining this again, neuro. You are right on and your explanation has helped me a lot as most of my lenses are f/2.8 and I like to to take a lot of bust portraits, especially with my 70-200 f/2.8. Until you explained this to me I thought my camera had a defect.

Brian

 

[YuengLinger]

The 60D, except for the center point, has a better AF system than the 6D!

The 80D is way ahead of either, but why are you comparing a FF to a crop in your title? Just seems odd with the apparent differences in both focal lengths and the real differences image quality.

I think the AF point I use LEAST is the center point. (Ok, I'm sure there are extreme outer points that don't get used as often as, but, really, I rarely use the center point. Just too difficult to compensate AF correctly with a fast lens, as Neuro explained.)

People defend the 6D's AF, declare it fine, etc, but I thought the 5DIII AF was good. Then I tried the 5DIV.

Point being, we are happy with what we have until we try something better.

Hi YuengLinger,

You make an excellent point with one exception: unfortunately, some of us must settle with a Camry and can only drool about the Lexus.

Brian

I actually do drive a Camry--because I take pics with a 5DIV.

 

[wsmith96]

Thanks all. Sounds like the 6D isn't terrible. Just put it through it's paces a bit at an orchestra performance on Sunday and got some spectacularly creative shots. The test will come with "running" events, but so far so good.
One thing I really do appreciate is the simplicity so there's that if all else fails and I just sort of feel slightly bad-a**ed with a full-frame camera. It's what'll tag along for the pending trip to Cinque Terre, Florence and Lake Como (from which, naturally, pictures posted here will follow).

I've used a 6D to shoot dive meets and tennis matches. For me it performed somewhere between good and great. Depending up on the running event, I think it will perform fine for you. What you'll miss is a faster frame rate if you are not dead on with your timing.

 

[hbr]

I actually do drive a Camry--because I take pics with a 5DIV.

LOL

 

[Cory]

If it helps - I've had 2 M5's and 3 M3's and just bought a 1.4T VW Jetta and love it.

 

[gruhl28]

Neuro, thanks a lot for the explanation. I had no idea that lenses with curved fields curve in the "wrong" direction - I'd always assumed they tended to curve in a circular shape with the area of focus towards the edges closer to the camera rather than further away.

 

[Jopa]

If it helps - I've had 2 M5's and 3 M3's and just bought a 1.4T VW Jetta and love it.

2 BMW M5 and 3 BMW M3? Not bad...