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Lens distortion correction is a resolution killer

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verybiglebowski said:
Promit said:
I don't see people complaining that m4/3 lenses are too soft, indeed they have some of the sharpest lenses around. And nearly all of those lenses are software corrected. So it's apparently possible to get good results from software correction, even if they are not the best possible results.

IMO if you sit down and really look at the effects of distortion correction on sharpness of real lenses in real world images, then decide that it's an unacceptable compromise? You're no longer a photographer, you're just a laboratory junkie.
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Tell that to Ansel Adams...

I really don't understand, why technical perfection should not be a part of the artistic expression. The form is always needed to express the content, and as such it is important part of overall perception.

I think it comes to the old - taking or making images point of view. If you are snapping life around you, transforming moments in memories or document things and happenings around you, flexibility of a zoom lens, convenience of the small system and simplicity of capturing (such as jpeg ooc i.e.), are much more important than ultimate image quality.

But if you are planning your image several days, months or years in advance, if you walk 100 times to the same location in 4 am hoping for that unique lighting situation, if you prepare your set-up and your models with lot of effort to materialize your vision, things just gets reversed. You will (or should) strive for every single pixel perfection (or intended imperfection), because that is a part of a creative process.

To say about someone who shot his flower in the living room, arranging background, lighting, framing, DOF etc. for many hours, that he is not using "real lenses in a real world images" and that he is not "photographer but just a lab junkie" is unfortunate misunderstanding of photography itself. Being it perceived as an art form, or just a technical tool for documentation.
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Excellent post! One do not get why some people are against a more scientific approach to taking an image. I enjoy planning, studying, thinking about how to best use my gear and overall preparing shots in advance. Also since I do not have terribly long experience with photography so without proper planning my intuition may fail me when I'm actually taking a pic unless I have done my homework very well.

I recently went to a city trip in Europe in a busy schedule but there was one specific place I wanted to photograph so I studied place well in advance, how long it takes to get there from a hotel etc. To take most of weather change effect out of equation I decided to shoot at night as the place is veru nicely lit. I knew roughly where I would shoot from before I even boarded the plane, I knew the lens and aperture I would use etc. I could have made nice shot even with SEL1650, but I enjoyed the whole process more knowing I was going to use decent equipment (Nex-7 + SEL1018 + IR remote + tripod) after all the prep. In the end I did quite ok and I was happy on what I shot that night in less than 45 minutes spent on site. I would have gotten nowhere near that result unless I "lab-ratted" the scenario well in advance.

 
Depends on the subject. If it's railroad tracks or telephone wires then yes they have to converge. But as far as the photos posted by blue skies upthread, it depends. If your subject is something up the far wall then the verticals need to converge. If it's the people or anything else at eye level, then the verticals should be parallel. It's simple perspective.
 
verybiglebowski said:
I agree with most of your statements (except software distortion correction), I just had a feeling that you are saying that software correction is perfectly ok for everyone, and who doesn't think so, is not a photographer but a lab jerk.
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Nothing is perfectly ok for everyone and I did not intend to imply that. But I feel that the effects of distortion on sharpness, particularly relative to optically corrected lenses (rather than uncorrected lenses) is being dramatically overstated.

I suppose my overarching point would be that at the end of the day, a lens is the sum of ALL its compromises and it's unreasonable to reject a lens simply because it's doing software correction.
 
As an addendum, I'm slightly amused at having this discussion on the E-mount forum. Sorry but software correction is the least of the problems most of these lenses have ;-)
 
Promit said:
verybiglebowski said:
I agree with most of your statements (except software distortion correction), I just had a feeling that you are saying that software correction is perfectly ok for everyone, and who doesn't think so, is not a photographer but a lab jerk.
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Nothing is perfectly ok for everyone and I did not intend to imply that. But I feel that the effects of distortion on sharpness, particularly relative to optically corrected lenses (rather than uncorrected lenses) is being dramatically overstated.
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Dramatically overstated is probably dramatically overstated. The difference in IQ can be huge for me and irrelevant for you, but we might agree that it's there.
Promit said:
I suppose my overarching point would be that at the end of the day, a lens is the sum of ALL its compromises and it's unreasonable to reject a lens simply because it's doing software correction.
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No lens should be rejected for any reason, including software correction of course. But no photographer should be rejected either, because its refusal of software corrected lenses or pixel peeping. We are all different and we all have different priorities. That's why there are so many options...

--
Don't trust your eyes or mind, they might betray you! Trust only comments posted on the forums, because there is the absolute truth!
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Keit ll said:
What are you more likely to notice in an image , obvious distortion or a marginal loss of centre resolution ?
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I don't think that's the point. For me it's an important question as then when you consider the IQ quality of a lens, you really have to factor distortion.

One example: the Sigma 85mm DG DN 1.4. Uncorrected, the distortions are so large you can't use the image as is. Corrected, it's perfectly fine. But, one of Sigma argument for the lens is: "we focused on overall better optics and let the camera body do the correction". If the corrections doesn't affect IQ too much, that's indeed a great solution. But if it does impact IQ too much, then lenses as this one might reveal to be useless (you usually buy that type of lens for great rendering and IQ)
 
You are a new member and probably unaware of this, but you should NOT resurrect a thread dead since 2013!!
 
forpetessake said:
Have you noticed that enabling distortion correction in camera significantly affects image resolution? Interestingly it happens not only in the corners where distortions are the worst, but even the center resolution suffers noticeably.
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That's exactly why good glass is so significant. If resolution is an important aspect to someone, they should better not go for lenses with undercorrected design (for reasons of lower design complexity, lower size and weight) and that rely on software corrections.

--
www.flicker.com/davidsphotoblog777
 
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forpetessake said:
Have you noticed that enabling distortion correction in camera significantly affects image resolution? Interestingly it happens not only in the corners where distortions are the worst, but even the center resolution suffers noticeably.
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Yes, it affects resolution in areas that, for example, had to be expanded, and so there's less density of information there.

But I don't think any information that was there before the correction is lost. It's just that there's not so much of it after correction per unit area of the correction.
 
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