D800 Left Af Check - Focus Point Moving Post Crop in NX2?

Hi,

I decided to do a quick check with L, R and C AF with my D800 and I opened each file in CNX2. Initial finding were that the left and right backfocused equally while the center point was dead on.

Ok, that's fine, but then upon further checking I saw something weird when looking at the af point in nx2. I was on a tripod, 10 second delay, f8, ISO 100. I'll only post the left screenshots, but I have left and right files I could post if need be.

When I look at the af point on the left af photo, it looks to be focused in the correct place as intended, but backfocused. So, I cropped that image to post what I thought was going to be a different issue because I thought I had a left and right af issue, not only a left (different from the typical af problem post) and was curious if anyone else had that.

Weird thing was that when I cropped the image, the focus point moved in NX2 and if that focus point is correct on the cropped image, something else seems to be going on and it is focused correctly to itself, but that doesn't correspond to what is shown as the true focus point in the viewfinder.

Here is the left focus point, pre-crop:





Here is the left focus point (same image) post-crop:





See what happened? NX2 moved what they called the focus point!

If what happened was correct, what's going on here? It's almost like they know where it focused, but aren't processing it correctly - or am I simply not understanding what is going on with what happens to a focus point once you crop an image?

I can't imagine that the focus point should move just because I cropped an image.

Here is a link to the full image if anyone cares...:

http://www.ryanwardenterprises.com/DSC_3654 (dot)NEF
--
Ryan Ward
http://www.premieratlantarealestate.com

I just tried it on a NEF in Capture NX2.

Does seems to place it correctly in the uncropped image, but keeps the same relative percentage location even if you crop outside of the red square entirely. Cropping to some area where there is no red focus square puts one there. Weird.

Does seem to be odd they do that move post-crop, which does mean it is in the wrong place once cropped.

Mack

GMack said:

Does seem to be odd they do that move post-crop, which does mean it is in the wrong place once cropped.

Mack

Click to expand...

Well, what's weird to me is that it coincidentally corresponds to where it's actually correctly focused...

--
Ryan Ward
http://www.premieratlantarealestate.com

The focus point does not display correctly in CNX2 after you crop - it's been that way for as long as I've used it (several years)

Do you know if it coincidentally goes to the place in the photo where it is actually focused like in the example I posted?
--
Ryan Ward
http://www.premieratlantarealestate.com

RyanWard said:

Do you know if it coincidentally goes to the place in the photo where it is actually focused like in the example I posted?
--
Ryan Ward
http://www.premieratlantarealestate.com

Click to expand...

No! the focus is point is not displayed correctly after cropping and the new (wrong) position is crop depended only - tt has nothing to do with actual focus point.

You are number 53 I have seen posting an image at dpreview complaining of D800 focus accuracy using a target where Nikon caution Please note that the camera may believe focus has been acquired

If you do not know why the target might be the problem have a look at page 100 of your D800 instruction book headed "Getting good results with autofocus".
--
Leonard Shepherd

Many problems turn out to be a lack of intimate knowledge of complex modern camera equipment.

RyanWard said:

Well, what's weird to me is that it coincidentally corresponds to where it's actually correctly focused...

Click to expand...

My hunch is your camera is backfocusing to begin with, and your 'cropped image' with the new red focus square just happens to fall on the sharper quarter behind the front one.

Might try the same thing and a -15 in your AF Tuning for that lens/camera combo and see what and where the uncropped red focus square shows.

Mack

Leonard Shepherd said:

You are number 53 I have seen posting an image at dpreview complaining of D800 focus accuracy using a target where Nikon caution Please note that the camera may believe focus has been acquired

If you do not know why the target might be the problem have a look at page 100 of your D800 instruction book headed "Getting good results with autofocus".
--
Leonard Shepherd

Many problems turn out to be a lack of intimate knowledge of complex modern camera equipment.

Click to expand...

Baying at the moon again I see.

Leonard Shepherd said:

You are number 53 I have seen posting an image at dpreview complaining of D800 focus accuracy using a target where Nikon caution Please note that the camera may believe focus has been acquired

If you do not know why the target might be the problem have a look at page 100 of your D800 instruction book headed "Getting good results with autofocus".
--
Leonard Shepherd

Many problems turn out to be a lack of intimate knowledge of complex modern camera equipment.

Click to expand...

I know you are mostly just a troll but out of interest, what's wrong with that target? It's has plenty of contrast, clear edges, no reflections, fine detail, no repeating geometric patterns etc. I'd expect ANY camera to be able to focus on a coin on a desk in well-lit conditions.

--
My travel photography blog - http://www.frescoglobe.com

The coin seems pretty dull to me overall. I'd assume a better shot at it if targeting the EDGE of the coin in respect to the table, not the center of it.

AF is still pretty inaccurate when it gets thrown a curve ball... and even the best systems have weaknesses. Nothing wrong with that. Difference between my mom and I is that she doesn't know that and I do. We photographers make decisions to get around limitations in our systems.
--
Manny
http://www.pbase.com/gonzalu/
http://www.thrustimages.com/
FCAS Member - http://fcasmembers.com/

Leonard Shepherd said:

You are number 53 I have seen posting an image at dpreview complaining of D800 focus accuracy using a target where Nikon caution Please note that the camera may believe focus has been acquired

If you do not know why the target might be the problem have a look at page 100 of your D800 instruction book headed "Getting good results with autofocus".
--
Leonard Shepherd

Many problems turn out to be a lack of intimate knowledge of complex modern camera equipment.

Click to expand...

Did you even read the original post?

Bostjan Pulko said:

No! the focus is point is not displayed correctly after cropping and the new (wrong) position is crop depended only - tt has nothing to do with actual focus point.

Click to expand...

Ok, that seems to answer my question - thank you.

GMack said:

My hunch is your camera is backfocusing to begin with, and your 'cropped image' with the new red focus square just happens to fall on the sharper quarter behind the front one.

Might try the same thing and a -15 in your AF Tuning for that lens/camera combo and see what and where the uncropped red focus square shows.

Mack

Click to expand...

Left and right seem to back focus about the same while the center is not backfocusing so I don't think AF fine tuning is the solution.

I've also just recently had the lens (24-70) in for recent alignment with an authorized Nikon service center.

gonzalu said:

The coin seems pretty dull to me overall. I'd assume a better shot at it if targeting the EDGE of the coin in respect to the table, not the center of it.

AF is still pretty inaccurate when it gets thrown a curve ball... and even the best systems have weaknesses. Nothing wrong with that. Difference between my mom and I is that she doesn't know that and I do. We photographers make decisions to get around limitations in our systems.

Click to expand...

Camera had no problem acquiring focus using AF-S Single point on left, center or right focus point. No hunting. It did not seem to have any issues. Also, it acquired focus using the center point accurately. I realize this is a cross type and the left and right points are not.

This doesn't appear to be a left AF issue as the left and right are off by the same amount. I just found it weird that when cropped, the new AF point that showed in NX2 appeared in the place where the camera actually focused. I wanted to know if this is some kind of aberration (which to people here say it is) or if there was something in the software that it actually new where to focus but focused wrong.

--
Ryan Ward
http://www.premieratlantarealestate.com

Boy you are one confused individual. If we are to go by your standard, every single bad AF is 100% user error. There is no freaking way a camera can be at fault because Nikon said so on page 100.

Leonard Shepherd said:

You are number 53 I have seen posting an image at dpreview complaining of D800 focus accuracy using a target where Nikon caution Please note that the camera may believe focus has been acquired

If you do not know why the target might be the problem have a look at page 100 of your D800 instruction book headed "Getting good results with autofocus".
--
Leonard Shepherd

Many problems turn out to be a lack of intimate knowledge of complex modern camera equipment.

Click to expand...