6d Focusing Problems

[perklax]

Hello,

I've recently purchased a 6d. It's a great camera and I love the look it has, but I'm having all sorts of troubles focusing. I mainly do portraits, and that requires me to consitently hit sharp focus on the eyes. For the life of me I can't do that. I'll focus on the eye using the middle autofocus point and then will recompose and take the picture, but it still won't work. It works half the time, but that's not good enough at all. It's been driving me crazy and I can't confidently go into a shoot. I'm getting paid for shoots also, so this isn't acceptable. 

[TTMartin]

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@Peter wrote:

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@perklax wrote:

I guess my question is should I be manually selecting the autofocus point, focusing on the eye, and then recomposing or just compose and let the autofocus select the point/points? I just want to confidently be able to hit focus in most situations. 

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Aim with your closest af point and remember that the focus af point is bigger than point you see in the viewfinder.

If you want to try you can also change your focus screen to one for manual focus.  It is really easy to do. It will give you a darker viewfinder but you will be able to focus manually and will never need to recompose or try to find the closest af point. I used that for one year in Japan together with my 5D and Helios 58/2.

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I have the Super Precision (S) viewfinder screen in my 7D Mk II, and had it in my 50D. It was one of the things I missed with the classic 7D.

[perklax]

I only use the primes actually. Never had the zoom. But when shooting vertically oriented portraits, I usually have to focus with the outermost one, which has almost always caused a soft image. 

[TTMartin]

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@perklax wrote:

I only use the primes actually. Never had the zoom. But when shooting vertically oriented portraits, I usually have to focus with the outermost one, which has almost always caused a soft image. 

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You need to be aware that on the 6D that is not a cross type focus point. It is only sensitive to contrast in one direction. Normally with the pupil of the eye being round this is not an issue. But, you should visually confirm the focus in the viewfinder. And as already mentioned, that AF point is larger than what you see in the viewfinder, so it may be picking up on the eyebrow, instead of the eye. 

[perklax]

Thanks to everyone. Appreciate the help!

[Peter]

It is also possible that your af needs a calibration. You can try it out using a tripode and a high contrast thingy (maybe a bare code) two three meters away.

You can start with focusing with center point through the viewfinder 5-8 times. Unfocus between every shoot. When you are done you take one shoot in live view. If you get a sharper image on the high contrast thingy with live view, then you will need adjust your af. The best way is to send the camera and lenses to calibration. The second best is to self try to microadjust the af from the menu.

[Waddizzle]

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@perklax wrote:

I only use the primes actually. Never had the zoom. But when shooting vertically oriented portraits, I usually have to focus with the outermost one, which has almost always caused a soft image. 

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If you are selecting just a single AF point with a 6D, you will get best results with the center point.  The remaining 10 points are useful for the "Basic" modes, and are practically useless in any of the "Creative" modes.  Stick to using just the center point in Creative modes, and you will get better results.  I say, focus and recompose.  Others, say not.

If you want "PRECISE" focus for portraits, you will not get consistent results relying on the camera's AF system.  The reason is really simple.  The AF system is not very exact, because like all electronic systems there is some error..  The AF system has a margin of error, and that margin error is nearly as large as the DoF with wide apertures at short distances. 

Exactly where the camera locks down focus can vary slightly.  Manually focus for the most ciritical shots.

[Peter]

Correct me if I am wrong.

Perklax uses a 85/1,8

The angle of view is 16 degrees on the short side and 24 on the long side. 28 degrees diagonal.  If you make a huge recompose about 10 degrees at 150 cm you will get the focal plane 2,28 cm away from you. At 150 cm and a 6D with 85/1,8 the "acceptable" depth of field will be from around 148.33 cm to 151.71 cm

If the recompose will be a smaller one, maybe the half of it ( the difference between the center point and the one most far away?) the focal plane will move around 0,57 cm away with 5 degrees. Acceptable? Only you can decide that, but every photographer should know what will happen when you recompose.

[Waddizzle]

"If the recompose will be a smaller one, maybe the half of it ( the difference between the center point and the one most far away?) the focal plane will move around 0,57 cm away with 5 degrees. Acceptable? Only you can decide that, but every photographer should know what will happen when you recompose" 

http://www.learn.usa.canon.com/resources/articles/2015/tips-for-getting-sharp-images.shtml

You are making the assumption that the plane of focus is flat.  For many lenses, it is not.  Try taking a picture of a wide wall mural sometime, or a wide, large, flat side of a building.  The outside edges can become out of focus.  Something similar happens when people try to "scan" old photos by taking pictures of them, and the edges are out of focus. 

Unless you have a macro lens, then the plane of focus is most likely not a perfectly flat plane, but more of a curved surface.

But, all of this moot, because if you want your "PRECISE" focus, then you probably shouldn't be relying on the camera's AF system to perform the focusing for you.  If you want "PRECISE", then focus manually.

[EDIT]  The curved plane of focus applies at both ends of the lens...what is going into it at the front, and what is coming out of it at the back.  The focus plane of the subject, and the focus plane of the image being projected onto the image sensor. 

[perklax]

[perklax]

A lot of it is stuff like this. Nothing is in focus and it's all blurry. Settings were 1/150th, f/5.0 and iso 1000. I made the shutter longer to account for the fact that I was missing focus, which I thought was that I wasnt stopped down enough. But I'm not sure what the real problem is. Motion blur?