7D Mark II - Focus Discussions

As a lot of people her I have also completely inconstant focus results with me Canon 7D II. On the photos below i used the 7D2 with 400mm f5.6L using back button focusing with the AF-ON button programmed. AI servo with Case 1. The focus points are on the subject, I checked this with a focus-point plugin. Continues shooting 10 frames. 1 photo in focus the next one out of focus. 1/1000 f5.6 400mm. Same crop in each image. I constantly get results like this but only if I use AI servo mode. I sent the camera to canon for repair they said the camera is ok. I don't know what to do.

Bernd1 wrote in post #17450369
As a lot of people her I have also completely inconstant focus results with me Canon 7D II. On the photos below i used the 7D2 with 400mm f5.6L using back button focusing with the AF-ON button programmed. AI servo with Case 1. The focus points are on the subject, I checked this with a focus-point plugin. Continues shooting 10 frames. 1 photo in focus the next one out of focus. 1/1000 f5.6 400mm. Same crop in each image. I constantly get results like this but only if I use AI servo mode. I sent the camera to canon for repair they said the camera is ok. I don't know what to do.

Do you hold the back button in until the shutter is released?

Yes continuously since I am in AI servo mode and the bird moved, although it did not move a lot.

Are these the full size photos or crops?

huntersdad wrote in post #17450558
Are these the full size photos or crops?

Crops but the same crop in each photo.

We need the full picture to assess.

Here are the full Pictures

Here are the focus points...

It picked up the water, not the bird. The bird is too small in the frame for the focus mode you used. That would have been an excellent situation to use single point or spot focus on pick up just the bird.

huntersdad wrote in post #17450649
It picked up the water, not the bird. The bird is too small in the frame for the focus mode you used. That would have been an excellent situation to use single point or spot focus on pick up just the bird.

I agree on this assessment. In the second shot, you can see the ripples immediately past water line has sharp focus. . Your dof is pretty shallow. Remember the actual Af points on the detector are larger than the indicators in Vf.

In my experience too, sometimes the camera will use the outer AF points when using AF point expansion. Don't give it the chance - select only one AF point.

I went out yesterday and tried to use the full 65 point AF ( Case 1). Out of 50 shots all were OOF. Even the ones with ducks in a clear blue sky. The focus points were on the ducks but focus was not. Until I figure out what went wrong I will not use them. I was using AI servo and back button focus. I'm also using 1st image and 2nd image as focus.

This was using the older 100-400. I'm finding sometimes it more the lens capability than the camera. I will work the lens a bit more to nail down why. Else the lens and camera in a tight AF works great.

Quite a major crop too. This would have an effect on relative sharpness too right?

TeamSpeed wrote in post #17449968
1/160th is often not fast enough to overcome both your focal length, AND your movement in conjunction with your subject, especially with no flash. It may have worked out from time to time on a lesser resolution body, but for a sensor with twice the resolution, you need to speed up the shutter a bit, especially if you zoom in to look at 100%.

I think there is a slight misconception about the sensor resolution and how that effects the capabilities of the camera. There is truth to the statement when the image is cropped significantly but barring that exception, there should be no disadvantage to using a higher resolution sensor. I would argue that a crop tight enough to show resolution issues on a 7D2 would not have been successful on the lesser camera either.

If I were to compare two uncropped photos of the same subject, one from a high-res camera and the other from a low-res camera, at the same print/display size, I would expect the high-res image to be as good if not better. In this test I would not expect to have to double shutter speed in order to achieve the same result.

Either I am misunderstanding the science behind this argument or the majority of shooters talking about these focus issues are in fact cropping their images heavily. If anyone can point me back in the right direction please do so.

MNiceGuy wrote in post #17450969
I think there is a slight misconception about the sensor resolution and how that effects the capabilities of the camera. There is truth to the statement when the image is cropped significantly but barring that exception, there should be no disadvantage to using a higher resolution sensor. I would argue that a crop tight enough to show resolution issues on a 7D2 would not have been successful on the lesser camera either.

If I were to compare two uncropped photos of the same subject, one from a high-res camera and the other from a low-res camera, at the same print/display size, I would expect the high-res image to be as good if not better. In this test I would not expect to have to double shutter speed in order to achieve the same result.

Either I am misunderstanding the science behind this argument or the majority of shooters talking about these focus issues are in fact cropping their images heavily. If anyone can point me back in the right direction please do so.

I tend to agree with you. I don't see an image disadvantage to using the higher resolution cameras. Thing is if you crop an image to the same content the higher resolution sensor should have more detail. It you crop the image to the same number of pixels the higher resolution image will be zoomed in tighter. This could make blur or OF more visible. But if you zoom the lower resolution image to the same content then it has the same issues. The only downsides to higher resolution I see are buffering, card speed and computer power. Besides printing or viewing images at anything other than 1-1 are interpolated images anyway.

Mike