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Archive 2014 · Issue with the Sony Zeiss 55/1.8 FE or A7

Jochenb
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p.1 #1 · p.1 #1 · Issue with the Sony Zeiss 55/1.8 FE or A7

I got the A7 and 55/1.8 FE last week. The lens can deliver stunning results, but I'm noticing some very strange behavior.
Here's a full size test shot to show what I mean:
example

It's shot at F1.8 because it shows the issue the best that way. Focus was on the tree in the middle. Now look at the right side of the frame. The rooftop of the building in the background is in focus. That's not the case on the left side. The plane of focus seems to be all over the place.

Seems like I once again got a faulty copy or might there be something weird about the lens design?
The strange thing is that it doesn't show issues when shooting more in the closer ranges or stopped down enough to hide it. Even testshots of planar subjects like a wall don't reveal any problems.
Lloyd Chambers noticed the same issue with his copy of the lens.
How do your copies behave at these distances?

Thanks.

Edited on Mar 02, 2014 at 02:40 PM · View previous versions

Feb 27, 2014 at 02:21 PM

snapsy
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p.1 #2 · p.1 #2 · Issue with the Sony Zeiss 55/1.8 FE or A7

Perhaps the two rooftops are not the same distance/plane of focus from the sensor.

Feb 27, 2014 at 02:25 PM

edwardkaraa
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p.1 #3 · p.1 #3 · Issue with the Sony Zeiss 55/1.8 FE or A7

Some cases of decentering or a tilted element will show up only at certain distances, when the faulty element comes into play. I would do the usual tilted horizon test to determine whether it's decentering or just field curvature. However my copy shows none and has practically zero curvature at infinity, even wide open.

Feb 27, 2014 at 02:31 PM

Jochenb
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p.1 #4 · p.1 #4 · Issue with the Sony Zeiss 55/1.8 FE or A7

snapsy wrote:
Perhaps the two rooftops are not the same distance/plane of focus from the sensor.

That doesn't really matter because:
- It's shot wide open so it shouldn't even show anything in focus in the background
- Apart from the branches of the left tree in the foreground nothing is in focus behind it on the left side.

Feb 27, 2014 at 02:31 PM

ryankarr
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p.1 #5 · p.1 #5 · Issue with the Sony Zeiss 55/1.8 FE or A7

Turn the camera upside down and take the same photo. See if it's repeated on the other side.

Feb 27, 2014 at 02:51 PM

snapsy
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p.1 #6 · p.1 #6 · Issue with the Sony Zeiss 55/1.8 FE or A7

Jochenb wrote:
That doesn't really matter because:
- It's shot wide open so it shouldn't even show anything in focus in the background
- Apart from the branches of the left tree in the foreground nothing is in focus behind it on the left side.

oops, you're right, I didn't look closely enough. I would go with the tilted element theory. The foreground bush at the very bottom of the frame is more in focus on the left edge than the center.

Feb 27, 2014 at 02:59 PM

Jochenb
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p.1 #7 · p.1 #7 · Issue with the Sony Zeiss 55/1.8 FE or A7

ryankarr wrote:
Turn the camera upside down and take the same photo. See if it's repeated on the other side.

I already tried that with another test scene. It didn't look exactly the same on the other side, but this might be because of slightly different focus. I did notice that the left side was a littlebit more in focus when shooting upsidedown so another indication of a faulty lens.
I'm currently going through my results from normal shooting and I keep seeing strange things. This must be a faulty copy. Yet again argh.
I was curious to know how the copies of the other users here behave, because I saw that Lloyd Chambers had the exact same issue with his. I also contacted him and he says that the lens has very strong field curvature at the edges. Slight asymmetry might exaggerate this.

Feb 27, 2014 at 03:49 PM

freaklikeme
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p.1 #8 · p.1 #8 · Issue with the Sony Zeiss 55/1.8 FE or A7

None of those rooftops are completely in focus. The one on the right side of the frame is closer to the plane of focus, and the tight repeating pattern makes it look more in focus than it is, but it's not completely sharp (like the tree, or part of the fence and gate). Perspective does matter. I'm not saying your lens doesn't have an issue, just that this sample isn't conclusive. I'd trying shooting something where the edges are equal distance from the lens (brick walls are good for something).

Feb 27, 2014 at 06:23 PM

ebrandon
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p.1 #9 · p.1 #9 · Issue with the Sony Zeiss 55/1.8 FE or A7

I had a FE 55mm that had decentering -- weak left side at infinity. Returned it to B&H, and my second copy is perfect.

Feb 27, 2014 at 06:25 PM

Jochenb
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p.1 #10 · p.1 #10 · Issue with the Sony Zeiss 55/1.8 FE or A7

freaklikeme wrote:
None of those rooftops are completely in focus. The one on the right side of the frame is closer to the plane of focus, and the tight repeating pattern makes it look more in focus than it is, but it's not completely sharp (like the tree, or part of the fence and gate). Perspective does matter. I'm not saying your lens doesn't have an issue, just that this sample isn't conclusive. I'd trying shooting something where the edges are equal distance from the lens (brick walls are good for something).

But why is the plane of focus near anyway? Looks like strong field curvature while nobody here has ever noticed it with their copies. Brick walls don't show the issue, nothing at closer ranges.

Here's another example:

Shot at F2, focus on the island of trees.

100% crop of the focus point:

Now, a 100% crop of the background near the center:

All still looks fine...
But then the crop of the extreme right edge:

Look at the treetops. They are in focus, yet at the same distance as the trees in the middle of the background. I don't think this kind of field curvature is normal for this lens?

*edit: fixed link

Edited on Feb 27, 2014 at 07:34 PM · View previous versions

Feb 27, 2014 at 07:12 PM

Makten
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p.1 #11 · p.1 #11 · Issue with the Sony Zeiss 55/1.8 FE or A7

Almost every fastish lens will give larger DOF towards the edges and corners, because of the entrance pupil being smaller at an angle (cats eye effect). Unless there is a clear difference between opposite corners, there's nothing wrong. And it's not curvature of field, just DOF being thinner at the center.

Feb 27, 2014 at 07:25 PM

Jochenb
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p.1 #12 · p.1 #12 · Issue with the Sony Zeiss 55/1.8 FE or A7

Makten wrote:
Almost every fastish lens will give larger DOF towards the edges and corners, because of the entrance pupil being smaller at an angle (cats eye effect). Unless there is a clear difference between opposite corners, there's nothing wrong. And it's not curvature of field, just DOF being thinner at the center.

Ok, that's interesting. I didn't know that. The difference is quite big though.

Feb 27, 2014 at 07:36 PM

freaklikeme
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p.1 #13 · p.1 #13 · Issue with the Sony Zeiss 55/1.8 FE or A7

That seems a bit more definitive. But it does seem odd to me that an issue like decentering would only show up at mid to long distances.

Feb 27, 2014 at 07:46 PM

Jochenb
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p.1 #14 · p.1 #14 · Issue with the Sony Zeiss 55/1.8 FE or A7

freaklikeme wrote:
That seems a bit more definitive. But it does seem odd to me that an issue like decentering would only show up at mid to long distances.

I've heard that it's possible. Edward also mentioned it in this thread earlier. That's what makes this so strange and why I started the thread. I've had several decentered lenses before, but all showed the issue when I did a testshot of a brick wall. Not this lens.

Final example for now:

Shot at F4 this time.

center crop:

right edge:

left edge:

There's still a littlebit of sharpness in this crop, at the bottom, but it's thin. The DOF looks deeper at the right edge and center crops.

I'm appreciating your thoughts.

Feb 27, 2014 at 08:02 PM

snapsy
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p.1 #15 · p.1 #15 · Issue with the Sony Zeiss 55/1.8 FE or A7

Maybe if it's the focusable element that's tilted/decent and the tilt only occurs at a certain focus position.

Feb 27, 2014 at 08:22 PM

Jochenb
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p.1 #16 · p.1 #16 · Issue with the Sony Zeiss 55/1.8 FE or A7

snapsy wrote:
Maybe if it's the focusable element that's tilted/decent and the tilt only occurs at a certain focus position.

That's possible. I also don't see an issue when focusing at infinity, it's only when I focus at midrange without reaching infinity that I get weird results. I've never experienced this before with a lens. Maybe it's just best that I try to get another copy and hope for the best.

Feb 28, 2014 at 03:18 AM

Toothwalker
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p.1 #17 · p.1 #17 · Issue with the Sony Zeiss 55/1.8 FE or A7

Jochenb wrote:
That's possible. I also don't see an issue when focusing at infinity, it's only when I focus at midrange without reaching infinity that I get weird results. I've never experienced this before with a lens. Maybe it's just best that I try to get another copy and hope for the best.

I experience something similar with my ZE 2/25. Sometimes the left border looks worse than the right border, also when everything is at infinity as far as the laws of optics are concerned. However, reproducibility is an issue, meaning that on other occasions both sides look jolly fine. I decided to accept the lens as is, also because the response of the camera store where I bought it was: "We hope you find a solution." All images from this lens look fine from a normal viewing distance, anyway.

Feb 28, 2014 at 12:02 PM

Jochenb
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p.1 #18 · p.1 #18 · Issue with the Sony Zeiss 55/1.8 FE or A7

Toothwalker wrote:
I experience something similar with my ZE 2/25. Sometimes the left border looks worse than the right border, also when everything is at infinity as far as the laws of optics are concerned. However, reproducibility is an issue, meaning that on other occasions both sides look jolly fine. I decided to accept the lens as is, also because the response of the camera store where I bought it was: "We hope you find a solution." All images from this lens look fine from a normal viewing distance, anyway.

I'm sorry to hear that. The good thing is that you've accepted it.
I exchanged my copy for a new one today. The store's reaction: "it's highly unlikely that lenses can be decentered nowadays"... right.

We'll see if this new copy is a better one.

Feb 28, 2014 at 02:32 PM

Jman13
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p.1 #19 · p.1 #19 · Issue with the Sony Zeiss 55/1.8 FE or A7

I had a badly tilted element in my Olympus 12mm...it acted like a tilt-shift with permanent tilt as well. Just exchange. Not worth going crazy about it.

Feb 28, 2014 at 02:42 PM

AhamB
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p.1 #20 · p.1 #20 · Issue with the Sony Zeiss 55/1.8 FE or A7

I have similar issues with multiple lenses on my 5Dc, but I think that's because I may have bent the mount a little bit with a 200/2.8 lens. I don't always see it, but sometimes there seems to be more DOF on one side.

Feb 28, 2014 at 03:09 PM

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