55 1.8

[tashley]

I've given mine a good going over and have some preliminary conclusions.

Sharp wide open, improves to the sweet spot of F4 to F5.6, diffraction quite noticeable at F8.

Very good but not perfect resistance to flare and CA

Quite low colour shading effects

Nice bokeh, generally round looking but in at least one shot, pentagonal. Go figure.

Just over medium contrast.

Mine is (grrrrr) decentered. The third Sony Zeiss lens in a row where the first copy I had should not have passed QC IMHO.

Here's a growing gallery with Lens Cast shots (with and without corrections on) and flare and bokeh and CA examples, and some focus shift tests that imply there is indeed a tendency for the field of focus to move backwards but for the subject to remain in good focus as you stop down. There are also near and far aperture series, best from bracketed.

The camera totally missed focus with this lens in good light a small number of times, not something I was seeing with the 35mm F2.8..

 

[Deleted member 7792]

I've given mine a good going over and have some preliminary conclusions.

Thanks Tim. I downloaded a couple of the photos from your gallery to view at 100%. I could count the bricks on the buildings behind The Empress. :thumbs: Contrast and bokeh look good. I especially like the rendering on the image of the woman in red sitting next to the path/road along the sea.

I just ordered the lens from Amazon. Should be here on Saturday.

Joe

 

[vjbelle]

Tim, a decentered lens is something I won't tolerate. That will be one of the first things I test for when I get mine. Its a real shame that regardless of manufacturer decentering slips by QC...... or I really should say they LET it slip by.:thumbdown:

Victor

 

[tashley]

Victor, take a look at the brick wall examples if you have time - and maybe the harbour series too. They are all downloadable as 100% size jpeg from RAW. I am curious to see if other people's tolerance for decentering is similar to mine!

 

[jlm]

a question i have always had lurking...
typically if shooting a landscape, even an urban landscape, there are always parts of interest at varying object distances. in addition, using the brick wall as a paradigm implies that focus is the same across the wall even though trig tells us the object distances vary L.C, R. (consider the hasselblad "true focus" solution).

which leads me to think there is no such thing as a "plane of focus"

??

 

[fmueller]

Victor, take a look at the brick wall examples if you have time - and maybe the harbour series too. They are all downloadable as 100% size jpeg from RAW. I am curious to see if other people's tolerance for decentering is similar to mine!

Took a look at a couple from the harbor series @1.8 and 4.0. I see the left edge is a little off. Same for the Candy Floss shot.

As an aside, I am so sad that my 50 Summilux ASPH is suffering at the edges at large apertures, haven't really tried/tested it stopped down yet.

 

[k-hawinkler]

Could someone please elaborate a tad what the tell tale signs of a decentered lens are?
Many thanks.

 

[tashley]

a question i have always had lurking...
typically if shooting a landscape, even an urban landscape, there are always parts of interest at varying object distances. in addition, using the brick wall as a paradigm implies that focus is the same across the wall even though trig tells us the object distances vary L.C, R. (consider the hasselblad "true focus" solution).

which leads me to think there is no such thing as a "plane of focus"

??

I've written endlessly about this elsewhere and there's no straight answer… but brick wall shots are useful because they show asymmetry.

 

[tashley]

Could someone please elaborate a tad what the tell tale signs of a decentered lens are?
Many thanks.

Sure: if you get parallel to a planar target and shoot it with focus on centre, and notice that the left and right or top and bottom or some opposing diagonal pair are differently sharp, you probably have a decentering. Most lenses of 50mm and wider I take delivery of have a little of this problem, avoiding it totally is beyond the manufacturing tolerances that are economic. I see it sometimes on Zeiss lenses, rarely on Leica, and quite a lot on less famous brands.

If you download each of the brick wall shots I linked to and layer them in Photoshop or flip between them in LR, you will see what I mean with this 55mm F1.8 and doing the same with the harbour shots, (where the corners aren't visible in the planar scene so just look at the central section from left to right) you'll see the left side is consistently softer.

I disagree that the candy floss shot tells us anything: the subject is far from planar and you can't tell that it reaches the edges in the same plane as the plane of focus so for an F1.8 shot, it is likely not to have enough DOF for the bag on the left side to look hyper-sharp near the edge of the frame.

 

[Deleted member 7792]

a question i have always had lurking...
typically if shooting a landscape, even an urban landscape, there are always parts of interest at varying object distances. in addition, using the brick wall as a paradigm implies that focus is the same across the wall even though trig tells us the object distances vary L.C, R. (consider the hasselblad "true focus" solution).

which leads me to think there is no such thing as a "plane of focus"

??

The simple answer to your question is no, "plane of focus" is a myth just as "depth of field" is a myth. That point at which you focus will be the sharpest point in the frame. The closer the subject is to the camera, the more pronounced the difference in sharpness will be between the center focal point and the edges. If the subject is near infinity, "plane of focus" becomes more truth than fiction. That's my 2 cents.

Joe

 

[ashwinrao1]

By the way, 55's are in stock at Amazon US....

 

[vjbelle]

Victor, take a look at the brick wall examples if you have time - and maybe the harbour series too. They are all downloadable as 100% size jpeg from RAW. I am curious to see if other people's tolerance for decentering is similar to mine!

Tim, I downloaded 7142 and at f4.0 I think that things should pretty much snap together. If my lens shoots the same as yours it will be history.:thumbdown:

Victor

 

[pozzello]

Sure: if you get parallel to a planar target and shoot it with focus on centre, and notice that the left and right or top and bottom or some opposing diagonal pair are differently sharp, you probably have a decentering. Most lenses of 50mm and wider I take delivery of have a little of this problem, avoiding it totally is beyond the manufacturing tolerances that are economic. I see it sometimes on Zeiss lenses, rarely on Leica, and quite a lot on less famous brands.

If you download each of the brick wall shots I linked to and layer them in Photoshop or flip between them in LR, you will see what I mean with this 55mm F1.8 and doing the same with the harbour shots, (where the corners aren't visible in the planar scene so just look at the central section from left to right) you'll see the left side is consistently softer.

I disagree that the candy floss shot tells us anything: the subject is far from planar and you can't tell that it reaches the edges in the same plane as the plane of focus so for an F1.8 shot, it is likely not to have enough DOF for the bag on the left side to look hyper-sharp near the edge of the frame.

How do you know the camera is perfectly parallel ?

 

[Vivek]

How do you know the camera is perfectly parallel ?

It comes with a built in level, does it not?

 

[Deleted member 7792]

It comes with a built in level, does it not?

Level isn't the same as parallel. Measuring parallelism to a planar surface is more difficult than ensuring the camera is level. That's one of the flaws in most "brick wall" lens tests. If slightly out of parallel with a wide open aperture, the apparent "plane of focus" could look skewed.

I'm sure Tim does his magic to set up as parallel to these subjects as possible.

Joe

 

[tashley]

Tim, I downloaded 7142 and at f4.0 I think that things should pretty much snap together. If my lens shoots the same as yours it will be history.:thumbdown:

Victor

Thank you for the sanity check. Bummer is, I called the store today (not my usual dealer) and they are happy to accept the return by post but I won't get another before I go away in early January. Looks like I'll be taking the E-M1…

 

[pozzello]

Unless I'm mistaken I don't think the built-in in level will tell you if the camera is angled to the left or right of the subject.

 

[Vivek]

Unless I'm mistaken I don't think the built-in in level will tell you if the camera is angled to the left or right of the subject.

Correct. Thanks.

 

[tashley]

Regarding parallelism…

Some people favour the mirror technique. It is a clever idea but frankly, unless the mirror is set perfectly flush with the target plane, it won't work. Look at a tiled bathroom wall and see how subtly different all the reflective planes are.

So what I do is to choose a subject that has the sort of horizontal lines that are plumb-lined, then line it up by eye and by level. The eye is informed by experience and the level by my knowledge of whether that camera has a half accurate level or not, and whether it is sensitive.

But even that is an approximation: we all know that. So I ensure that I do several sets with different targets and at different distances and if a pattern emerges, I know I have 'an issue'. But actually, I think the brick wall shots I posted are pretty close.

 

[tashley]

Unless I'm mistaken I don't think the built-in in level will tell you if the camera is angled to the left or right of the subject.

Absolutely right for the level on its own - but, assuming the level is accurate, then if there are perfect horizontal lines in the subject, then the level will tell you exactly that.

EDIT: I should explain this: assuming that the level is 100% accurate in both up/down and side to side planes, then setting the camera on an Arca Cube and levelling it perfectly means that as you pan it across the subject, the point at which the perfect horizontal lines in your subject are perfectly parallel to the frame and frame lines is where you are perfectly 'true' to the subject.