800E focus problem

[travelfinn]

I have a 800E and been now for a few months trying low light shots of buildings and some landscapes, mainly with 14-24 2.8 lens and a few with the 70-200 VR1. Shooting tethered with the camranger. Shooting f8 ISO 100 and between 2 seconds and up to 30 seconds using the camranger to view the picture for highlights and shadows and adjusting accordingly the exposure. Shutter delay set at 3seconds. Framing and adjusting focus through the camranger because in many cases can’t use the camera viewfinder or live view. Sometimes I am shooting camera ground level, straight up or no space behind the camera. Live view in low light conditions on the camranger is grainy and blurred but after the first picture can check focus and composition. Been mainly using manual focus but a few days ago took a lot with autofocus as a test and got a big surprise.
When viewing them found sharp ones and blurred ones.
Have for example four identical pictures taken one minute apart. I took them because of the different clouds in the sky.
First and third one sharp jpeg size 16.9 and 17.6. The second and fourth one are 13.2 and 12.8.
Sharp ones a bit wider on the computer screen you notice it when switching between the two. The focus point square is a bit larger on the sharp ones and a bit towards the left. Checking the data sharp ones autofocus normal and blurred ones single and auto fine tune on (0). Can’t figure out why?
Checked all 60 photos the same result single blurred and normal sharp. In any case have ten good ones and the best result so far. I am seeing an improvement in my workflow after 25 times out taking low light pictures.

[NorthernFocus]

Hi, Ilmari. Welcome to CIC.

I also shoot an 800E. Though I shoot mostly wildlife, not much landscape. However I do a lot of low light (not night) shooting. I'm not sure after reading you post that I understand for sure. Please clarify the following:

1. Do you have OOF shots when using both manual and auto focus?
2. When using autofocus, which AF settings are you using? Which focus mode and number of points etc?
3. At what range are you typically focusing? How many meters from the camera to the focus point?

[dje]

Hi Ilmari and welcome from me too. I think the points that Dan makes could be quite relevant - but then he's not called NorthernFocus for nothing is he

I like to use manual focus in magnified Live View mode for this type of shot as with that approach, I know exactly what I am focussing on.

Does the autofocus work reliably in normal light conditions?

Dave

[AB26]

Checking the data sharp ones autofocus normal and blurred ones single and auto fine tune on (0). Can’t figure out why?

Hi Ilmari,

Welcome to CiC. Hope to see some images from your D800E.

Does the D800E have a feature that allows the shutter to be released in single point AF without obtaining focus but in multi point AF it will only release the shutter once focus is obtained?

[travelfinn]

Thank you for the welcomes.
Focus is AF-S and spot focusing. Shooting most scenes using 14mm DOF should be deep, in most cases nothing of interest in the foreground so focus distance is 20 30 meters.
Running a learning curve in steps the first two were exposure and composition so that no perspective correction needed. I switched from ball head to three way geared head as one solution. Now I am looking at sharpness. After that I will look at flare. Going step by step solving one just one problem a time.
Last night went through a lot of older shots and only a few with autofocus and most of them blurred or would soft be better to describe them. Did today a quick test with the 200mm lens and focus ok.
Been thinking the soft shots focus data AP-S single and sharp AP-S normal. Why that change.
On the camranger can first have live view and then press capture the camera takes the picture.
I can also press capture without live view then the camera a picture without live view.
So the camera focuses normally. But I am going out again to test the different variables for focusing.
After each shot going to write down what I did.
Camranger has focus peaking on the screen was showing focus ok.

[Manfred M]

I shoot the D800, not the D800E and did have some what I thought were "focus issues" on long exposures for night time shots. These ended up not being focus issues at all, just slightly soft images. Lenses in question were the f/2.8 24-70mm and the f.2.8 14-24mm.

I wonder if what you are seeing are camera movement, not focus issues. I ended up having to go to a much sturdier (i.e.more rigid) tripod for that type of shooting; including a columnless design. I also had to start sandbagging / wieghting the tripod for additional stability on really long exposures.

[travelfinn]

Using the Gitzo 2530 EX Center column down. Maybe that's the problem have to check it also. Uploaded two pairs of photos full resolution jpeg no pp Flikr photos kopiotaito. Not sure how do a direct link for full res. photos.

[NorthernFocus]

I agree with Manfred. It sounds more like motion blur due to camera shake. With a 14mm lens even with f2.8 aperture setting and focus at 3m, DOF carries out to infinity. With that lens I'd recommend shooting manual focus and concentrate on making sure you've done everything possible to eliminate camera shake.

[travelfinn]

I went out and did a test shoot. Found out that the culprit was the mirror and three seconds delay is not enough. When focusing only live view or manual sharpness perfect.
The metadata shows which one has been used AF Fine Tune: - contrast detection live view
AF Fine Tune: ON(0) phase detection
Camranger uses refocus after pressing capture and for that phase detection. That’s the reason for soft photos. With long exposures you hardly notice the softness shorter ones yes.
Just have to change the way I set up things. Use autofocus to focus then switch camera to manual focus and camranger also.

[PhotomanJohn]

Use autofocus to focus then switch camera to manual focus and camranger also.

Disable AF from shutter button and use AF-ON button to focus then you will never need to switch thereby making life simpler.

John

[NorthernFocus]

Glad you figured it out. It is astonishing how much vibration the mirror can cause. OK, now that you've figured that out it's time for you to post some photos here

[Manfred M]

The mirror slap can be a bit of an issue with some of the shorter exposures in the range you are looking at, but should have damped down at the longer end of the range. I suspect the issue has more to do with the AF not being disconnected and you getting a bit of seeking than vibrations from mirror slap.

Low light can mean autofocus issues, so if you use LiveView and magnify to focus, you should be able to get a sharp focus on manual. This of course means you have your mirror up and not causing any problems.

[NorthernFocus]

...I suspect the issue has more to do with the AF not being disconnected and you getting a bit of seeking than vibrations from mirror slap....

At least in theory AF locks while the shutter is open. That presumes that it behaves the same when activated by the remote/tethered device as with the button.

[travelfinn]

Was last night thinking about the two other differences in the pictures focus point and small difference in FOV. Set a plastic bottle on the table 33cm away from the camera focused on it. Did a none scientific test
Live view on the lens showed 0.35 and stopped on the point and normal focus showed left side of the zero. So the lens has a small focus problem.
Then took a lot of pictures with the camranger with different settings to check how different workflows work.
Downloaded the photos and studied them-
Live view focus point red square is always larger.
Live view focus point is lower the upper edge overlaps the low edge of the other one and sideways sometimes to the left.
Live view focuses closer to the bottle so the lens at this range has a focus problem. You can see the difference on the focus scale and viewing on the screen the live view image has a bit wider FOV. You see it when viewing the images quickly back and forth..
Camranger test for focusing. Camera AF on all the time
Capture no live view focus phase after triggering.
Live view autofocus on same result.
Live view auto focus on tap the screen anywhere and the camera will focus on that spot and on the screen AF-S and AF lights go out. Camera focuses contrast detection live view and takes the picture without refocusing with phase.
Can also zoom in and only then tap for focus also the histogram shows the value for the area on the screen.
So the AF on means phase and MF is contrast detection. Camera can be always on AF.
If I have to set the focus point of the camera at 4 meters I just walk 4 meters away and focus through the camranger on myself and if I need a person in the image can take a picture of me in it using live view to put myself in the right place.

[Manfred M]

At least in theory AF locks while the shutter is open. That presumes that it behaves the same when activated by the remote/tethered device as with the button.

Absolutely correct there Dan; what I found though was that if I left autofocus on in dim light, with LiveView, the camera would attempt to refocus when I triggered the shutter and might not always select the same focus point. Disabling autofocus after getting the correct focus point (assuming I used autofocus in the first place), mean that the camera would not try to refocus again and I would have a good, sharp focus.