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01-09-2021, 10:15 AM - 6 Likes   #1
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Some corner softness is no big deal. My eyeballs have it; not returning them.

I've lately ordered a copy of the DA 18-135 WR lens which should arrive shortly. While waiting, I've read ALL OF the long thread about the lens, which is filled with a gigantic number of excellent photographs members have taken with it. One thing,thread participants inevitably find themselves bemoaning from about a third of the way into that thread and on is how a few voices near the beginning repeatedly panned the lens for producing soft corners, even though the issue is hardly serious except for certain focal lengths at certain apertures.

This got me thinking, eventually leading to this questions:

DO I REALLY CARE A WIT ABOUT HAVING SUPER CORNER SHARPNESS IN MY PHOTOS MOST OF THE TIME?

Simple answer: NO, NOT MUCH.

* How often do I place a part of the subject matter that I particularly want to be seen with absolute clarity in the extreme corner of the image rectangle? Hardly ever.

* If what I want the viewer's eye to be drawn to is somewhere in some globby oval occupying the middle two thirds of that rectangle's area? Do I want them distracted by some sharp sparkly thing over in the corner? Absolutely not.

* One of my favorite forums here is the Bokeh thread--not a single corner-sharpness-oholic anywhere in that crowd!

Might certain subjects call for particularly good corner sharpness? Yes, documenting architectural design perhaps. How many of us call something that demanding of corner sharpness as a major part of our photography practice, I mean, really?

Even for much landscape photography, a little corner softness may be acceptable for many of us. Didn't we put what we want most attention paid to somewhere in that middling zone of the frame, not in the corner?

Let me make it clear--I DO KNOW how to get excellent corner sharpness in pictures:
--take pictures of flat things
--use a copy stand
--use a quality flatfield lens

And who would even expect that level of corner sharpness from any zoom lens in the first place, for criminy sakes?

I'm interested in what sort of debate--in a civil tone, of course--this little prompt might begin among PF members brave enough to identify themselves as corner-sharpness scoffers or devotees, as well as comments from those in the middle, who do demand corner sharpness in some cases, but who don't need it much in a lot of other circumstances.

Please post lots of example photos, as well as lens and technique info.

Thanks in advance,
Goats

01-09-2021, 10:50 AM - 1 Like   #2
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Yeah, I agree. I just got the 18-135 and have not noticed any "corner softness" unless I look at the screen at 100%. However, I don't look at photos that way, and the main subject keeps my eyes out of the corners anyway even if the subject is off center. So, no, corner softness is a non-issue in the real world, and only counts if you are doing a technical review, IMHO. I REALLY like the DA 18-135 BTW. I think it gives great images. My next step is to try it with a close-up filter for "macro shots!!
01-09-2021, 11:06 AM - 5 Likes   #3
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A few years back I was a little bit obsessed with the edge sharpness in pictures taken with my 16-85 zoom, or lack of in my slightly decentered example. No matter what the subject of a picture taken with this lens I would find myself zooming to 100% to see how blurry it was.
I then read an article which pointed out that if you are obsessing over edge sharpness and other lens defects in a picture then your photo just isn't that interesting. Who ever looked at a photograph by the likes of Joseph Kudelka, Cartier-Bresson or Robert Frank and examined the edges or corners over the main subject? In fact, if you do they often aren't that sharp...
01-09-2021, 11:41 AM   #4
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QuoteOriginally posted by goatsNdonkey Quote
DO I REALLY CARE A WIT ABOUT HAVING SUPER CORNER SHARPNESS IN MY PHOTOS MOST OF THE TIME?

Simple answer: NO, NOT MUCH.
I agree, the life of a pixel-peeper must be dreary and disappointing.

my DA 18-135mm WR is a keeper

01-09-2021, 11:48 AM - 1 Like   #5
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I agree that generally corner sharpness is not that important, but for my landscape photography I prefer lenses that are sharp across the frame (or at least not overly soft in the corners) because very often the subject is close to (or at) infinity focus (mountain ridges and the like) and in my opinion when the horizon gets soft near the corners it can actually draw attantion from the centre because of the occuring softness and there is not allways a interesting foreground to frame the shot, especially when you get above the timberline.
01-09-2021, 12:02 PM   #6
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DxO PhotoLab does a good job of improving corner sharpness in DA 18-135 photos.
01-09-2021, 12:04 PM - 1 Like   #7
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QuoteOriginally posted by othar Quote
I agree that generally corner sharpness is not that important, but for my landscape photography I prefer lenses that are sharp across the frame (or at least not overly soft in the corners) because very often the subject is close to (or at) infinity focus (mountain ridges and the like) and in my opinion when the horizon gets soft near the corners it can actually draw attantion from the centre because of the occuring softness and there is not allways a interesting foreground to frame the shot, especially when you get above the timberline.
That sounds like a very worthy exception. If the subject of a landscape shot is more the entire breadth of the view, and not certain central or foreground subject matter, then corner sharpness does become much more important. Then I suppose the question becomes, what degree of softness in the corners might be acceptable in such a shot. Maybe a little is okay, but there is a line not to cross.

01-09-2021, 12:11 PM - 2 Likes   #8
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We don't have to stay too tied to the DA 18-135mm WR in this discussion, but it is a lens that certainly brings up the issue. I was drawn to it because I found it as an opportunity to get my first WR lens to use with my K10D at a reasonable price. It also seemed to have a versatile range. But discussions of it inevitably bring up the corner sharpness/softness issue.

By comparison, my Helios 44-2 f/2 58mm prime has almost nothing but a circle of center sharpness! Still, it sees the world in wondrous ways.
01-09-2021, 12:24 PM - 1 Like   #9
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Corner sharpness is extremely important to me. In landscapes what's often there in the corners are tree branches or strands of grass. If the sharpness is any different from similar objects in other parts of the frame it jumps out at the viewer. Obviously it isn't always possible to design a lens for excellent sharpness across the frame but that should always be the objective. But decentering is much worse to me than design shortcomings - there is just no excuse for one side being different from another. Combine decentering with design shortcomings and you wind up with green blobs instead of branches or strands of grass around the edges of your photos. When I was learning photography and reading Adams' books I don't remember any (gray, of course) blobs around the edges in the examples, with maybe one or two exceptions (portraits, etc.)
01-09-2021, 12:43 PM - 2 Likes   #10
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QuoteOriginally posted by goatsNdonkey Quote
Then I suppose the question becomes, what degree of softness in the corners might be acceptable in such a shot.
I think the widespread use of HD monitors less than 24 inches away from our faces is the real culprit here. To take the most demanding application, reproducing flat printed materials with fine details, like a road map or a book with footnotes; in ancient days when xerography obsoleted Gutenburg's invention, as long as someone with average vision could pick out enough details to decipher it, the sharpness was acceptable. For us prehistoric viewers of photographic prints, what counted was the overall look (and subjective things like how deep and rich the photosensitive chemicals looked or how glossy the paper was); sharpness in the corners could take away from the overall look the photographer was trying to create. Mind you in those days, photographers didn't have to worry about being shunned for failing to keep their corners sharp.
01-09-2021, 01:02 PM - 2 Likes   #11
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A bit of corner softness, most of the time, doesn't matter much.

If you are doing exhibition sized prints then it may be important for deep field of view landscapes - in which case you are probably want the best lenses.

In any case if you have a lens that sharpens up once you stop down then you probably have it covered. An exception I can think of is night landscape shots with a subject in foreground and stars in the background where you don't want star trails - in this case you want pretty good performance with wide apertures.

Personally a significant proportion of my own shots I like, involve some amount of bokeh around the edges anyway.
01-09-2021, 01:03 PM   #12
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QuoteOriginally posted by RGlasel Quote
I think the widespread use of HD monitors less than 24 inches away from our faces is the real culprit here. To take the most demanding application, reproducing flat printed materials with fine details, like a road map or a book with footnotes; in ancient days when xerography obsoleted Gutenburg's invention, as long as someone with average vision could pick out enough details to decipher it, the sharpness was acceptable. For us prehistoric viewers of photographic prints, what counted was the overall look (and subjective things like how deep and rich the photosensitive chemicals looked or how glossy the paper was); sharpness in the corners could take away from the overall look the photographer was trying to create. Mind you in those days, photographers didn't have to worry about being shunned for failing to keep their corners sharp.
I have a wonderful over-sized book of Edward Steichen's early photgraphs, back from around the time when he made his classic portrait of the sculptor Rodin. It can be hard to find a single place in an image that is truly sharp, for there might be only one small area in the one spot he thought it was necessary. Some of the pictures are so full of blacks and every manner of rich deep grays, that it can be equally as hard to find a similarly intentional speck of true white in a picture. I wonder how many lenses he had? I don't think a computer designed their formulae.
01-09-2021, 01:04 PM   #13
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Sharp VS Fuzzy corners

Having to choose between an "overall sharp" lens and one with fuzzy corners in well-lit landscape photography, I prefer the former to the latter. I even went the medium-format way (645Z) to get well-corrected optics and I use a tripod and middle apertures like f/11. Some artful "atmosphere" images with dark corners can tolerate subpar fuzzy corners, though.

P645 35 mm f/3.5

P67 90-180 mm f/5.6

Last edited by RICHARD L.; 01-09-2021 at 01:19 PM.
01-09-2021, 01:27 PM - 1 Like   #14
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@goatsNdonkey covered most of the key dimensions of the debate. Yes, some shots for some types of photographic genres (astro, art/archival reproduction, architecture, and landscape) do benefit from corner-to-corner sharpness. And most other photos work beter with central sharpness and edge/corner softness (either due to the lens or bokeh/out-of-focus conditions).

One big factor that can favor of soft-corner-lenses in almost all genres of photography is that sharp-corner lenses tend to be large, expensive, and have limited or no zoom. For on-the-go photography on a budget or with weight constraints, a lens such as the 18-135 WR is far far superior to a bag full of sharper lenses. In the realm of travel and hiking photography, the photographer with a single light-weight zoom will get more shots of more different subjects than the photographer who was burdened by carrying and swapping a bunch of heavy, sharp lenses.

Sometimes it's better to have a soft-corner image than no image at all because the sharp-corner-lenses were too expensive, too heavy to carry on a trip/hike, or took too long to swap.
01-09-2021, 02:01 PM - 1 Like   #15
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QuoteOriginally posted by photoptimist Quote
Sometimes it's better to have a soft-corner image than no image at all because the sharp-corner-lenses were too expensive, too heavy to carry on a trip/hike, or took too long to swap.
Totally true, Sir.

Regards
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