EOS 6D Mark II Conflicts between viewfinder focusing and Live View focusing

[Skip70]

Canon 6D Mark II
I am using the Tamron Tap-In console to do micro-focusing on what is now my all stable of Tamron lenses. I am finding a very obvious difference between focus points using the viewfinder and reference focus point using touch screen Live View. 

I will try to attach the photos to this post, but the first time using the regular viewfinder focus (spot focus and metering)the focus point) was front focus. I adjusted using the console forward, just as you would with there Canon micro-focus system. However, when I did the same shot zooming in on LiveView, the focus point was clearly back focus, reflecting the influence of my adjustments. 

The simplest way say this is that the camera is finding a different focus point on the viewfinder method than it is finding using LiveView. While there is always adjustment we can make on a lens, I'm concerned that there is an issue with the camera. 

Ideas?

[jrhoffman75]

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@Skip70 wrote:

I am doing micro-adjustment (as I have done for years with all of my lenses) to correct back- or front-focus. In my latest case, when taking a test photo with viewfinder, it showed front focus. When I did exactly the sums photo using Live View, was generally at zero midpoint. (I did provide photos in my original post.)

My simple point is that the viewfinder focus and the Live View focus ought to be the same, otherwise we would never know which one to trust. 

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If Live View and viewfinder focusing results aren’t the same then the camera isn’t calibrated correctly. That is the whole point of AFMA. Something is fundamentally wrong. How are you doing AFMA?

[Waddizzle]

 “ That's all I was trying to do today until I realized the differential between viewfinder and LiveView. One picture taken with the viewfinder would clearly show front focus; the Live View would show back focus. That suggests to me some issues within the camera. “

I would suggest clearing the focus settings and retesting before you try to recalibrate.  Performing a focus adjustment is not a simple task. It’s far easier to get it wrong than it is to get it right. I have used the Dot Tune Method in the past with excellent results.

[jrhoffman75]

Ablation (Latin: ablatio – removal) is the removal or destruction of something from an object by vaporization, chipping, erosive processes, or by other means. 

😀maybe the camera is attacking the subject. 

The photographic term is chromatic aberration. Nothing to do with the topic. 

[Waddizzle]

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@Skip70 wrote:

Canon 6D Mark II
I am using the Tamron Tap-In console to do micro-focusing on what is now my all stable of Tamron lenses. I am finding a very obvious difference between focus points using the viewfinder and reference focus point using touch screen Live View. 

I will try to attach the photos to this post, but the first time using the regular viewfinder focus (spot focus and metering)the focus point) was front focus. I adjusted using the console forward, just as you would with there Canon micro-focus system. However, when I did the same shot zooming in on LiveView, the focus point was clearly back focus, reflecting the influence of my adjustments. 

The simplest way say this is that the camera is finding a different focus point on the viewfinder method than it is finding using LiveView. While there is always adjustment we can make on a lens, I'm concerned that there is an issue with the camera. 

Ideas?

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BTW, are you I using a tripod?  Are there images cropped? The framing of your two test shots should be identical.  The framing of all your test shots should be identical.  

What lenses are you trying to calibarate? Or what lens was used for your posted samples?

[Skip70]

Thank you, John. You win the boxed set of Occam's Razors. That has been my question and assertion all sling /. Oth images should match. I may have a camera calibration in my future. 

[Skip70]

Of course I dm using a tripod.m Crooping of the final image was just to emphasize the differences and is irrelevant to the issue. I was calibrating a Tdmron SP 35mm 1.4, which has been widely praised for sharpness rivaling first party lenses. Either way, the issue here is not its ability to achieve focus per se but the difference between viewfinder and Live view. 

[jrhoffman75]

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@Skip70 wrote:

Thank you, John. You win the boxed set of Occam's Razors. That has been my question and assertion all sling /. Oth images should match. I may have a camera calibration in my future. 

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Before you do that try using a Canon lens. Separate out the internal calibration issue of the Tamron lens. 

[Skip70]

I have long understood this set-up. What I don't understand is your comment "Notice how the distance between the imaging sensor and the auto focus sensor will always be identical because why are the same sensor." Your diagram depicts that they are not: the image sensor is on the back wall of the divinity, the AF sensor, you said, is below. As well, while we may hope they may be identical. you say earlier that the whole point of AFMA is to adjust until they are. If I understand your point, then, I need to keep adjusting the AFMA until the viewfinder )prism) image matches what is coming off the image sensor (Live View).  

[Skip70]

I had so many helpful and expert responses yesterday I admittedly lost track of the line of thinking tracking all those on my iPhone, so get up this morning and carefully read all of them again. 

Here is what I take away, a new question , and my action plan:
1. The Life View is not subject to "adjustment" in that it is the actual image projected directly onto the sensor screen. When that's in focus, that will result in a focused image. 
2. If, then, an image from the viewfinder system is different, it simply means there is a misalignment or miscalibration in that system. That is what AFMA is designed to address -- making minute physical changes in the alignment of the sensor at the bottom of the mirror box so it matches what would be projected directly onto the image sensor. 

The remaining question them, is that role an aftermarket lens calibration system, e.g. Tamron's Tap-In Console has. It is designed to address front and back focus issues, but I'm wondering if it in some way actually may be trying to do the same thing as Canon's AFMA method. If I expand the proposed image in Live View and actually select a focus point on a test card, the final fox point ought to be why I selected, not something in front of or behind that point.