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05-15-2012, 09:58 PM   #31
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What a waste of my time.

05-15-2012, 10:12 PM   #32
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QuoteOriginally posted by wlachan Quote
What a waste of my time.
And your money...
05-16-2012, 02:27 AM   #33
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QuoteOriginally posted by wlachan Quote
Just show me one full size DA15 shot which is sharp corner to corner.
This shot was sharp enough corner to corner for me. I've had some shots with the same lens that are a bit soft in the extreme corners. I suspect focus position has an impact on the effect of field curvature.



Full size - http://farm8.staticflickr.com/7073/7208476772_ee775c6b76_o.jpg

ISO1000 on K7, so not perfect at 100%!
05-16-2012, 10:52 AM   #34
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QuoteOriginally posted by Weber Quote
I own the DA 21, and I initially felt let down by the seemingly soft corners (they are more or less like the DA15 shot the OP showed here, maybe a touch softer still).

However, when I started making large prints (larger than 20", some up to 25" wide), I immediately shut up and stopped complaining. The amount of corner softness from the lens wasn't even perceptible in the print, even when viewed close up.

We need to stop pixel-peeping, I think. It does not tell us much about how prints will look.
Agreed! I own the 15 and the 21. They are both sweet, tiny lenses. The OP asks a valid question especially when you're new to a lens and you want to make sure it's up to snuff, but I think everyone has answered with an affirmative "it's a great lens and competes with the best even at its diminutive size, and its characteristics are very understandable from a physics perspective". When you shoot subjects that actually matter, the corners are a non-issue. Enjoy it and take photos of things that interest you. Now the decentering on my 55-300 is another matter......

05-16-2012, 03:59 PM   #35
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Definitely "soft" in the corners but I assume it's a trade off for the smaller size. I hope.
05-16-2012, 04:07 PM   #36
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QuoteOriginally posted by wlachan Quote
I am quite aware of the PZ tests and also checkout their actual samples. Regardless of what their actual figures are (which don't take field curvature into account), the samples are what matters the most. In the cases of Pentax DA14/15, all their samples have poor edge/corners sharpness which are the result of severe field curvature.
The only way field curvature will be the cause of soft corners will be if you are shooting the equivalent of brick walls. Real world scenes of that FOV seldom have corners in the same plane as the center. If the samples have poor corner sharpness at anything but f/4, it's not field curvature but just a simple matter of DOF - the corners are too far from the focus plane.
05-16-2012, 04:19 PM   #37
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QuoteOriginally posted by Marc Sabatella Quote
The only way field curvature will be the cause of soft corners will be if you are shooting the equivalent of brick walls. Real world scenes of that FOV seldom have corners in the same plane as the center. If the samples have poor corner sharpness at anything but f/4, it's not field curvature but just a simple matter of DOF - the corners are too far from the focus plane.
That's not been my experience after owning 3 DA14, and I was shooting real scenery at f8-11 with varies focus to confirm my findings multi-times. I even test them on 40D with 10X VF to make sure it wasn't my technique or imagination. This is the only lens that behaves so badly in my experience. Severe field curvature DOES impact actual performance greatly. Trying to brush this issue off with brick wall test or whatever non-sense is not going to work. Well, what do I care anyway.
05-16-2012, 07:10 PM   #38
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Well, I've really opened a can of worms with this thread. All I really wanted to do was to find out if I had got a good copy or a bad copy. I suppose I have to conclude from the posts that the lens is working as it should. As has been pointed ou people don't usually go around shooting brick walls. Well I certainly don't. In the mean time I've been out and about snapping away and I like the fov and the results I have been getting ESPECIALLY situational shooting which is probably where I will use it the most so the corners aren't really a concern.

When it comes to landscapes I haven't a clue. Just to give an idea of what a novice I am I spent yesterday trying to figure out why when autofocusing on distant mountains the lens didn't go to infinity. I have since discovered I should be using manual focus and distance scale.

Thanks again for all the comments.

05-16-2012, 07:20 PM   #39
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QuoteOriginally posted by wlachan Quote
That's not been my experience after owning 3 DA14
So you are posting based on your usage of a different lens! Feel free to waste your own time and money on ridiculously bad Canon lenses, but stop wasting other peoples time here as well as confusing the issue being discussed.
05-16-2012, 10:10 PM   #40
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QuoteOriginally posted by wlachan Quote
That's not been my experience after owning 3 DA14
I am not sure when the discussion shifted to the DA14, but we were talking about the DA15 here. So I assumed your criticism were about that lens. And that is what I am taking issue with. It's sharpness is *excellent* - yes, even in the corners when stopped down to the sort of apertures you'd actually use when shooting landscapes.

Since you challenged people to post examples, here are a few. Resized versions attached, links to the full size versions below. As these images show, the claim that the DA15 is not good enough for landscape is just plain *preposterous* in every possible way. It's as sharp as one could possible hope for *everywhere in the frame*, plus it is remarkably free from distortion and from CA, and it is perhaps one of the most flare resistant lens ever made. You aren't going to beat it as a landscape lens at that focal length. Far from being not good enough, it is *as good as it gets*.


Full size: http://marcsabatella.zenfolio.com/img/s3/v45/p702438765.jpg


Full size: http://marcsabatella.zenfolio.com/img/s2/v52/p821578355.jpg


Full size: http://marcsabatella.zenfolio.com/img/s2/v52/p629161531.jpg
05-16-2012, 10:21 PM - 2 Likes   #41
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Nice ones Marc!

Now we just have to wait for the Canon troll girls to come along and complain that you didn't focus on the corner or that you didn't shoot a brick wall!
05-17-2012, 05:05 PM   #42
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No need to be harsh. And detractors of the DA15 come from within the Pentax world as well. But normally, most criticisms of the lens have to do with wide open performance softness only, and there it is possible to disagree over the *degree* and the *importance* of this. Thats where quibbling about field curvature, DOF, and what type of scenes one might want to shoot wide open can come into play and cannot really be resolved.

But when it comes to performance at typical landscape apertures, though, there just isn't anything there to complain about. Any such criticisms of the DA15 for its performance in typical landscape applications are simply based on misinformation, and that can be corrected. The photozone numbers and actual real world images tell the same story - this is the sharpest lens of its focal length range available for Pentax - and beyond that, it is also the best in terms of distortion, CA, and of course, its legendary flare resistance.

And while numbers cannot be directly compared across systems, it is still possible to some extrapolation (eg, seeing how corners MTF numbers look in comparison to center, also paying attention to what ranges Photozone calls "excellent" versus "very good: versus "good"), it also seems rather apparently that while the Canon 10-22 is very good for a zoom, there doesn't appear to be much likelihood that it actually beats the DA15 in *any* category, with the possible exception of distortion. While posting random images of different scenes from different photographers doesn't really prove anything, it can lend some anecdotal evidence in support of this read of the numbers: good as the 10-22 may be, there just doesn't appear to be any basis for believing it is better than the DA15.
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