02-18-2013, 11:56 AM
[quote name='Studor13' timestamp='1361125610' post='21981']
What a "fun" thread.
"As I also told you, the focus is behind the fructal"
For the 13th time (13 is my luck number) the focus is not behind the word Fructal.
If it were the little angel which is 35cm behind the Fructal box would be sharper in the 24-85 f4 image than it is in the 16-35 f4 image. But it is not. The 16-35 shot is noticeably sharper.
[/quote]
You are making many wrong assumptions. You cannot compare with the 16-35, because the characteristics (general sharpness, field curvature, AF calibration) may be very different from the 24-85 at represent, because you have not identified the problem of the 24-85.
You have obviously not looked very carefully at your 24-85 image. Where do you propose the focus is then IN THE CENTER, if not somewhere behind the fructal. It is obviously not in front, because the blur gets increasingly worse as you get closer to the camera - look at more things than just the "luna" text. The sharpest area in the center is still the window wood frame. If we do take the 16-35 f4 image as reference for DOF at f4, you can see that fructal to the window frame, even the angel is relatively sharp. So, we have a DOF of maybe 30 cms or more at that focal length and aperture.
Given that with the 24-85 f4 the window frame is just about sharp, I would guess that the center of the focal plane lies actually somewhat on the outside of the window. That the angel is not quite sharp can have several reasons, it's not in the center so maybe a bit softer in general, or some field curvature.
As mentioned before, since you focused on fructal, we need to examine sharpness in the immediate vicinity of fructal, and not somewhere else.
Have you bothered to read what we wrote about field curvature? Have you looked at the example link for the Tamron that I posted?
How sharp or not sharp the word Napkin is is totally irrelevant at present. The optimal focal plane towards the edge could be anywhere in front or that back, depending on the lens design. It CANNOT be used to deduce how the center will look!
It is simple, because the focal plane is not there, that's why it's not sharp! See posts above. You seem to argue that Fructal has to be sharp? Why? By what magical properties should the AF be sharp exactly in the center. We know if zillions of cases of front or backfocus, and all evidence, because on the image properties in the center (the edge cannot be used as reference), points to the fact that you have backfocus, both at f4 and f8.
A simple test with life view and center focusing would show if you can get the lens sharper, but why don't you try this, instead of arguing.
The handle is totally unsharp in both cases, so is useless for comparison.
What a "fun" thread.
"As I also told you, the focus is behind the fructal"
For the 13th time (13 is my luck number) the focus is not behind the word Fructal.
If it were the little angel which is 35cm behind the Fructal box would be sharper in the 24-85 f4 image than it is in the 16-35 f4 image. But it is not. The 16-35 shot is noticeably sharper.
[/quote]
You are making many wrong assumptions. You cannot compare with the 16-35, because the characteristics (general sharpness, field curvature, AF calibration) may be very different from the 24-85 at represent, because you have not identified the problem of the 24-85.
You have obviously not looked very carefully at your 24-85 image. Where do you propose the focus is then IN THE CENTER, if not somewhere behind the fructal. It is obviously not in front, because the blur gets increasingly worse as you get closer to the camera - look at more things than just the "luna" text. The sharpest area in the center is still the window wood frame. If we do take the 16-35 f4 image as reference for DOF at f4, you can see that fructal to the window frame, even the angel is relatively sharp. So, we have a DOF of maybe 30 cms or more at that focal length and aperture.
Given that with the 24-85 f4 the window frame is just about sharp, I would guess that the center of the focal plane lies actually somewhat on the outside of the window. That the angel is not quite sharp can have several reasons, it's not in the center so maybe a bit softer in general, or some field curvature.
As mentioned before, since you focused on fructal, we need to examine sharpness in the immediate vicinity of fructal, and not somewhere else.
Quote:Again, to see that the 24-85 isn't back focusing you need only to compare the word Napkins. I admit now that the f8 example is not perfect but the word Napkins there is near tack sharp. The reason the wooden structure through the windows are sharp is due to dof - the same reason why the word Napkin is equally sharp. And more importantly, the corners of the 24-85 f4 image is equally sharp - left or right. That is, the plane of focus is not tilted.
Have you bothered to read what we wrote about field curvature? Have you looked at the example link for the Tamron that I posted?
How sharp or not sharp the word Napkin is is totally irrelevant at present. The optimal focal plane towards the edge could be anywhere in front or that back, depending on the lens design. It CANNOT be used to deduce how the center will look!
Quote:Furthermore, look at the texture of the square white tiles going from say left to right. They are almost uniformly the same. This also tells me that the plane of focus is not tilted.
Again and again, look at the center. Almost nothing there is sharp! The word Luna in front AND behind Fructal (The point of focus), the angel, the 8Pk64 and the word Cholcolat. Nothing! Yet on the sides everything is relatively sharp for both the 24-85 and the 16-35 at f4.
It is simple, because the focal plane is not there, that's why it's not sharp! See posts above. You seem to argue that Fructal has to be sharp? Why? By what magical properties should the AF be sharp exactly in the center. We know if zillions of cases of front or backfocus, and all evidence, because on the image properties in the center (the edge cannot be used as reference), points to the fact that you have backfocus, both at f4 and f8.
A simple test with life view and center focusing would show if you can get the lens sharper, but why don't you try this, instead of arguing.
Quote:For the most extreme comparison you can look at the handle for the dishwasher in the left side foreground. There is no way that the 24-85 is back focusing and yet the handle is equally in focus as it is in the 16-35 image.
The handle is totally unsharp in both cases, so is useless for comparison.