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New Contributor
Posts: 2
Registered: ‎01-10-2018

1 pt autofocus is inaccurate

I have an EOS 70D with an EF-S 18-135 1:3.5–5.6 IS STM and EF lens 50mm 1:1.8 lens.

I typically shoot in 1pt autofocus and have realized that various points are inconsistent. For instance, when I place the camera on a tripod with the 18-135 and shoot using the center point my shot is sharp. However when I focus using an outside point the subject is completely out of focus.

I tried this same test with the 50mm and it’s better but but it still seems to be less sharp on the outside, just not nearly as bad as the 18-135.

Is the 18-135 lens faulty or is there a camera setting that will fix this? At this point I’m ruling out technique as a the culperate.

New Contributor
Posts: 2
Registered: ‎01-10-2018

Re: 1 pt autofocus is inaccurate

I should also note that I’ve always had focus issues with this lens. I only recently tested each point for accuracy
VIP
Posts: 8,469
Registered: ‎12-07-2012

Re: 1 pt autofocus is inaccurate

When you are not using center point "only" which is what I use 90% of the time, the cameras focuses on the closest thing.  Whether it is your intended subject or not.  I suspect that is what you are noticing. In other words what you think is in focus is different than what the camera thinks.

 

If you want precise focus on something turn off all the other focus points and use just the center.

A lot less stuff for 2018 but still a lot of Canon stuff. Along with, a lot of other stuff.
Honored Contributor
Posts: 5,861
Registered: ‎08-13-2015

Re: 1 pt autofocus is inaccurate


Andysdn wrote:
I have an EOS 70D with an EF-S 18-135 1:3.5–5.6 IS STM and EF lens 50mm 1:1.8 lens.

I typically shoot in 1pt autofocus and have realized that various points are inconsistent. For instance, when I place the camera on a tripod with the 18-135 and shoot using the center point my shot is sharp. However when I focus using an outside point the subject is completely out of focus.

I tried this same test with the 50mm and it’s better but but it still seems to be less sharp on the outside, just not nearly as bad as the 18-135.

Is the 18-135 lens faulty or is there a camera setting that will fix this? At this point I’m ruling out technique as a the culperate.


Are your subjects moving or stationary?

 

I suggest that you use One Shot mode, not AI Servo mode to take test shots.  Then, use DPP to see where the active AF point was located in the frame.  The center AF point is also the most sensitive and most accurate.  I would rather lock focus, and recompose the shot than use the center in One Shot mode.

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"I don't rent software. I use Photoshop CS6, ACR 9.8 and Lightroom 6.8 ."
Esteemed Contributor
Posts: 3,931
Registered: ‎06-25-2014

Re: 1 pt autofocus is inaccurate


Waddizzle wrote:

Andysdn wrote:
I have an EOS 70D with an EF-S 18-135 1:3.5–5.6 IS STM and EF lens 50mm 1:1.8 lens.

I typically shoot in 1pt autofocus and have realized that various points are inconsistent. For instance, when I place the camera on a tripod with the 18-135 and shoot using the center point my shot is sharp. However when I focus using an outside point the subject is completely out of focus.

I tried this same test with the 50mm and it’s better but but it still seems to be less sharp on the outside, just not nearly as bad as the 18-135.

Is the 18-135 lens faulty or is there a camera setting that will fix this? At this point I’m ruling out technique as a the culperate.


Are your subjects moving or stationary?

 

I suggest that you use One Shot mode, not AI Servo mode to take test shots.  Then, use DPP to see where the active AF point was located in the frame.  The center AF point is also the most sensitive and most accurate.  I would rather lock focus, and recompose the shot than use the center in One Shot mode.



Waddizzle wrote:

Andysdn wrote:
I have an EOS 70D with an EF-S 18-135 1:3.5–5.6 IS STM and EF lens 50mm 1:1.8 lens.

I typically shoot in 1pt autofocus and have realized that various points are inconsistent. For instance, when I place the camera on a tripod with the 18-135 and shoot using the center point my shot is sharp. However when I focus using an outside point the subject is completely out of focus.

I tried this same test with the 50mm and it’s better but but it still seems to be less sharp on the outside, just not nearly as bad as the 18-135.

Is the 18-135 lens faulty or is there a camera setting that will fix this? At this point I’m ruling out technique as a the culperate.


Are your subjects moving or stationary?

 

I suggest that you use One Shot mode, not AI Servo mode to take test shots.  Then, use DPP to see where the active AF point was located in the frame.  The center AF point is also the most sensitive and most accurate.  I would rather lock focus, and recompose the shot than use the center in One Shot mode.


That doesn't make sense to me. Did you mean to say "I would rather lock focus and recompose the shot than use anything but the center in One Shot mode"?

Bob
Boston, Massachusetts USA
Highlighted
Honored Contributor
Posts: 5,861
Registered: ‎08-13-2015

Re: 1 pt autofocus is inaccurate

“That doesn't make sense to me. Did you mean to say "I would rather lock focus and recompose the shot than use anything but the center in One Shot mode“

 

You are correct.   It did come out backwards,  I meant exactly what you wrote.  Bad eyes failed me again.

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"I don't rent software. I use Photoshop CS6, ACR 9.8 and Lightroom 6.8 ."
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