Canon Ef 16-35 f4 Decentered or some other issue?

MitchAlsup wrote:

Hayden N wrote:

CameraCarl wrote:

Exactly where were you focused for the landscape shot? How far away was your target? Were you on a tripod? The corners are probably unsharp because they are out of the depth of field. To test this, find another brick wall that is the same distance from your camera that your focusing point for the landscape shot was. Then repeat your brick wall test and check your results. Another way to check for decentering is to take a photo, then rotate the camera 180 degrees (turn it upside down) and take the same photo. Then check the edges and corners. Franky I don't think there is anything wrong with the lens. It isn't going to be sharp edge to edge and corner to corner at f4 under the conditions you faced in that landscape. You need to stop down even a wide angle lens.

Focus for the landscape photo was on the trees just to the right of buildings which were at least 1km into the distance,was handheld, Even at f4 I would expect the plain of focus to cover everything but the foreground.

Will try the other method you mentioned.

It is clear that the point of the image in focus is that grove of trees/bushes.

F/4 does not have "that" great a Depth of Field.

For a shot like this, you should be using F/8-F/11. But because of the high resolution sensor (50MP) you should try to stay away from F/11 as much as you can (it has its own blur start to show up.)

Don't forget that the size of the circle of confusion used for calculating depth of field depends on the print size. The usual standard is about 30 micrometres for something like an A4 print. That's about 7x the pixel pitch of your 5Ds (4.13 micrometres). In other words, unless you can specify your circle of confusion or a huge print size, you should calculate the depth of field for 5 or 6 stops wider than the one you are using if you're concerned about pixel sharpness at its limits. Lack of depth of field can cost you a lot more sharpness than diffraction softening, which is why macro lenses, traditionally the sharpest lenses in a system, used to stop down to f/32.