D800 + wide angle trouble nailing focus

[Ernicus]

quick question...if I have say a dragon fly in view...focus point on eye...half press and get the beep, then move to re frame...will capture still show focus point as the eye or where ever the dot that it used for the focal point end up in the frame?

 

[Ernicus]

I just answered my own question. Turns out that is not a very helpful tool at all. In the image below I focused on the "enter" key, half shutter press, got beep, moved center point to cigarette pack. Focus stayed on the "enter" key as I wanted it to, but the focus point shows the smoke pack as focus point.

So in relation to this thread, the focus point on the deer means nothing if you moved to reframe shot in any slightest direction.

 

[cgipson1]

When you re-frame.. you are moving the focus point! That is why focus and re-compose gets so many people in trouble!

 

[Ernicus]

When you re-frame.. you are moving the focus point! That is why focus and re-compose gets so many people in trouble!

Well sure you are technically moving the "focus point" as the dot you used as your point indicator moves...but you have also locked in focus on a different point of the image...so that should be reflected as your true focal point, as in the area of the image that was the focus point.

Or am I playing on words here?

 

[cgipson1]

When you re-frame.. you are moving the focus point! That is why focus and re-compose gets so many people in trouble!

Well sure you are technically moving the "focus point" as the dot you used as your point indicator moves...but you have also locked in focus on a different point of the image...so that should be reflected as your true focal point, as in the area of the image that was the focus point.

Or am I playing on words here?

The area of focus is where the focus point is in the viewfinder when you lock focus. And it stays at the point in the viewfinder, even if you then point the camera straight up in the air and actuate! The camera doesn't know any better (YOU locked the focus) and it can't pass that change to software! Does that help?

 

[Heitz]

We need exif data... Were you actually spot focus (single point AF) mode and AF-S? .. or were you in one of the other focus modes? If you were in AF-S.. the focus point only shows in Single Point Mode....Auto doesn't show it. If you were in AF-C.. the focus point shows in Single Point, D9, D21, D51 and 3D.. but not in Auto.

It would also help to see a full size image...

Good catch cgipson1. It was not AF-S, it was AF-C with 9 focus points, not 1. Which means that it is possible I could have focused on the tree above the deer, then moved down some and the camera wouldn't have refocused if the tree was still within the 9-point region. I'm continuing to do tests with single-point AF-C or AF-S (never auto).

 

[cgipson1]

We need exif data... Were you actually spot focus (single point AF) mode and AF-S? .. or were you in one of the other focus modes? If you were in AF-S.. the focus point only shows in Single Point Mode....Auto doesn't show it. If you were in AF-C.. the focus point shows in Single Point, D9, D21, D51 and 3D.. but not in Auto.

It would also help to see a full size image...

Good catch cgipson1. It was not AF-S, it was AF-C with 9 focus points, not 1. Which means that it is possible I could have focused on the tree above the deer, then moved down some and the camera wouldn't have refocused if the tree was still within the 9-point region. I'm continuing to do tests with single-point AF-C or AF-S (never auto).

damn.. I actually got something right for a change! lol! Glad I could help!

 

[BXPhoto]

Well to be honest, 1/200th even at the FL can create minor hand shake. Also the lens could simply be back focusing. Or he recomposed and didnt realize it. Too many variables to be used as a test shot. Also look at all the artifacts in front of the focus point and before it. Even my 7D/5d2 in spot focus/center point could have had an issue due to user error. Take a shot in bright light in an open area of a contrasty subject on a tripod. This way it will remove a few variables (steady hands, accidental recomposure etc).

 

[spacefuzz]

Also dont be afraid to jack up the ISO on the D800, I have gotten really nice shots even as high as 3200.

 

[Heitz]

Update -- The Nikon 20-35 2.8D had a huge back focus on my D800. Corrected with AF Fine-tune -15.

Curious -- anyone know what causes back focus for a particular lens? Don't quite understand why that would happen.

 

[BlueMeanieTSi]

Yeah the branches behind the tree that is behind the deer are pretty dang sharp.