Edge sharpness ?

[dee]

In the 70s/80s i do not recall so much concern about edge sharpness in prime lenses .
I guess it was true for Leica owners but if my Rokkors softened at the extreme , I had no issue with that The advent of inexpensive kit zooms in the Minolta AF era must have compounded the 'problem ' and I for one , missed the ability to buy an excellent 50mm F1.7 at a give away price .
Does this worry you overmuch ?
dee

 

[goamules]

Not at all, I like a lens to look a little old fashioned at the edges, it distinguishes my photos from all the cellphone pics. I do find it funny that in any thread profiling a lens, someone will always pop in with a comment "yeah, but the corners look a little soft..." I think, So? It's an internet theme that has built it up.

 

[Spanik]

Depends a bit on the subject and intention of the photo. But mostly I don't care much if it isn't exagerated.

 

[mfogiel]

For portrait or documentary photography, the subject most often is near the centre of the frame, and in any case what counts is "being there".
With a 35mm digital bodies that exhibit medium format like resolution, suddenly a 35mm camera is becoming a do all tool, including landscape and architecture. That's why the edge sharpness concern. Not to mention, that almost nobody can make great photos, but everybody can pixel peep at 400%.

 

[Rob-F]

Depends a bit on the subject and intention of the photo. But mostly I don't care much if it isn't exagerated.

+1. Falloff of sharpness and illumination at the edges and corners is an optical law. It has to be that way. It is just a question of how much. Personally, I would prefer the falloff to be minimal, but as long as it isn't too obvious, I'm fine with it. I don't go testing for it.

 

[uhoh7]

I look at it all the time. Where it matters. Landscapes especially and architecture.

I also have lenses I use often which are not as strong on the edges, but it's horses for courses:

here my landscape 50:

L1031970 by unoh7, 50 Cron

Just a humdrum shot, but it has fantastic edges. Below is the 50 I often take visiting friends:


L1031646 by unoh7, Sonnetar

The Sonnetar is just as weak as the original CZJ Sonnar on the edges, no matter the aperture, but I enjoy the render and other aspects 🙂

Now, corners......are a funny thing. I have some lenses which are better in the extreme corners, relative to alternatives, yet have mid frame weirdness, while my main landscape 35, the ZM 35/2, has softness in the extreme corners at all apertures, but is very even everywhere else.

What is especially annoying is edge issues which come from the sensor rather than the lens, as we see with the Sony A7 series, where a thick filter stack over the sensor makes it's own field curvature.

I had my own A7 modified to remove the thick stack and it's very nice now:


DSC07904 by unoh7, ZM 18 on A7

It seems many don't really know how to spot good or bad edges, as seen in what are often shown as "test" shots. For a proper shot to test the edges, you want infinity with distant details on the edges and at least one corner. For example:


a7m_28cron_f8 by unoh7, 28 cron on A7.mod

Obviously edges are not as sharp as the center, but pretty good, especially for 28mm on the A7. 🙂

 

[willie_901]

In the 70s and 80s people didn't view photographs with extreme scrutiny, a.k.a pixel peeping. Lens tests were few and far between. Computer simulations were uncommon for optic designs.

Contemporary mainstream lenses from all brands have sufficient edge resolution for most usage.

There are some situations where superior edge resolution make a difference. There are even fewer circumstance where edge resolution at wide apertures (~ f1.4 to 2.8) is vital.

I am not concerned with edge resolution.

I am much more interested in rendering for out-of-focus regions. For some reason, I find longitudinal chromatic aberrations to be very annoying. When I switched cameras brands, the low level of longitudinal chromatic aberration in the new brand's lens offerings was a significant factor in my decision.

 

[Dwig]

In the 70s and 80s people didn't view photographs with extreme scrutiny, a.k.a pixel peeping. Lens tests were few and far between. Computer simulations were uncommon for optic designs. ...

No, lens tests were very very commonly published from the late '50s onward in the popular photo magazines. Also, computer lens design was very very common throughout the '60s. "Pixel peeping" was done back then, though it was done by viewing the film through a lupe and limited by the film's resolution. There was frequent discussion in the columns in Modern Photography and Popular Photography in the early to mid '60s about lens testing methods and the then new MTF calculations.

The lens manufacturers that targeted the real professional and technical users generally put more weight in consistent performance across the whole image. It was those lenses that were targeting the price restricted user or the "snapshooter" that were designed with less emphasis on edge performance while retaining decent center performance.

 

[Corran]

Sometimes corner softness is more an issue with field curvature.

I notice it a lot with certain lenses, even highly regarded ones, and it is sometimes distressing when I'm shooting, say, a large group portrait at a wedding and all the folks in the left and right quarters are very clearly blurry even at moderate size viewing (full-screen, 24" or larger monitor).

Now mind you, I've never had anyone complain about said blurriness, since usually it's great-uncle Bob who they've met three times or something, but it does annoy me. I think it's field curvature usually as I'm always shooting at optimum apertures in those types of situations.

 

[willie_901]

Yes, field curvature is an important factor.

 

[Paul Jenkin]

If I'm shooting landscapes, I care a bit - but only to the point where the edge is acceptably sharp (to my taste). If I'm shooting street, travel or portraits, I generally couldn't care less about edge sharpness so long as the subject is acceptably sharp (to my taste). If I was shooting macro or medical, sharpness (generally) would probably matter a lot more.

The qualities portrayed by the background mean a lot more to me, so I tend to search for something that has a soft rendering for background. So far, I haven't found anything better than my Nikkor 105mm f2 DC which, ironically is also about as sharp as I've ever found.

 

[Monochrom]

Hi, i like edge sharpness a good quality image is always fine.
What´s the point of having for instance fast lenses if the result is poor?
If i´m trying some composition with the subject at the edges of the frame at least it must be sharp.
Not to mention landscapes or subjects at 5-10m.
Of course i´m not a bokeh or OFA fanatic either, results are very poor using that trick.

 

[Andrea Taurisano]

I do find it funny that in any thread profiling a lens, someone will always pop in with a comment "yeah, but the corners look a little soft..." I think, So? It's an internet theme that has built it up.

When I read comments like "yeah, but the corners look a little soft", my first thought is: Allright, if it's only a little soft, and only at the corners, it's not for me. I now hate that excessive sharpness that I used to strive (and spend lots of money ) for some years ago. I even swapped a Summicron 35 ASPH with a 'cron 35 v2.

 

[Paul Jenkin]

What´s the point of having for instance fast lenses if the result is poor?

Thing is, most fast lenses (f1.8 and faster - used wide open) aren't very sharp at all - even in the centre. There are a few exceptions but even if the subject stretches across the whole frame and we'd like it to be as sharp at the edge as at the centre, this is very unlikely to happen at wide apertures due to the very limited depth of field.

Assuming the goal is edge to edge sharpness and sharpness from toes to infinity is, an aperture of f8 - f22 is necessary. Results from good quality lenses with a maximum aperture of f3.5 and f4.5 (taken at f8-f22) are hard to distinguish from results from "fast" lenses" stopped down to f8 - f22.

Paying a lot of money for fast lenses tends to be for circumstances where one needs to isolate the subject from the background. I know that DOF blur is different to edge sharpness but, in most cases, we tend to place the subject either in the centre or on a "third".