Comments on: You CAN Correct It In Post, but . . . http://www.lensrentals.com/blog/2013/01/you-can-correct-it-in-post-but Photo/video thoughts from the largest rental house Tue, 21 May 2013 12:27:08 +0000 hourly 1 http://wordpress.org/?v=3.3.2 By: Lisandra http://www.lensrentals.com/blog/2013/01/you-can-correct-it-in-post-but/comment-page-1#comment-28074 Lisandra Tue, 29 Jan 2013 03:17:51 +0000 http://www.lensrentals.com/blog/?p=11605#comment-28074 aaaaaat any rate...you constantly answer things that keep me up at night. Resolution is the most important thing to me as of today (despite my favorite format being m4/3s) but I think distortion is more distracting overall than a bit of resolution loss. aaaaaat any rate…you constantly answer things that keep me up at night. Resolution is the most important thing to me as of today (despite my favorite format being m4/3s) but I think distortion is more distracting overall than a bit of resolution loss.

]]> By: Manuela http://www.lensrentals.com/blog/2013/01/you-can-correct-it-in-post-but/comment-page-1#comment-27406 Manuela Mon, 21 Jan 2013 07:21:31 +0000 http://www.lensrentals.com/blog/?p=11605#comment-27406 I meant "I am looking forward to further testing", sry for that, I am not English native. I meant “I am looking forward to further testing”, sry for that, I am not English native.

]]> By: Manuela http://www.lensrentals.com/blog/2013/01/you-can-correct-it-in-post-but/comment-page-1#comment-27405 Manuela Mon, 21 Jan 2013 07:18:27 +0000 http://www.lensrentals.com/blog/?p=11605#comment-27405 Roger, thank you very much for this test. I would have asked exact the same question as mph if I were the first here to comment. I am looking for further testing because in many fora people use the argument that distortion can be corrected and the loss of resolution is negligible. As I suspected there is in fact no free lunch. Roger, thank you very much for this test. I would have asked exact the same question as mph if I were the first here to comment. I am looking for further testing because in many fora people use the argument that distortion can be corrected and the loss of resolution is negligible. As I suspected there is in fact no free lunch.

]]> By: Gee Free http://www.lensrentals.com/blog/2013/01/you-can-correct-it-in-post-but/comment-page-1#comment-27249 Gee Free Thu, 17 Jan 2013 14:57:24 +0000 http://www.lensrentals.com/blog/?p=11605#comment-27249 Dear Roger,whenever I read your stuff I am always reminded of the late Geoffrey Crawley who wrote reviews for the British Journal of Photography back in the day. Your no-nonsense, cut-to-the-chase, fanboy-averse approach is so refreshing, welcome and much needed. What a different technical world photography is this digital realm. There is so much potential misinformation and confusion regarding real-world IQ and how to achieve it and how to maintain it. I got rid of a beloved, late, mint Nikkor 28/3.5 PC because the CA was just so outrageous that even after correction attempts in numerous software there was still what I can only describe as a white shadow where the red/purple fridge used to be. Your little article begins to explain why and points to a reality that what we use when we photograph is not just a sensor but a complete system (lens-sensor-electronics, etc)that often-times may deploy software manipulation (that is essenially what "firmware" is isn't it?)even at the AD stage. Notwithstanding that, if we have a "perfect" sensor that requires no AD tricks to be "perfect" and we use a lens that captures an image full of distortion that must be corrected via software and will thus detract from the "perfectness" of the sensor, then what is the point of lauding the camera manufacturer because of having a sensor whose full potential cannot be realized due to deficiencies in the camera manufacturer's lens line-up. Where to find information on real, genuine and practical image IQ that takes such into consideration? For example, I have yet to read anything on DxO's site that factors in the destructive effects of correcting for distortions like CA nor have they mentioned Nikon's manipulation of the analogue signal before it is converted to digital. Whether this is still an issue or not a do not know. But I remember reading that astronomical photographers would not use certain Nikon cameras because the noise reduction process used effectively cancelled out some of the stars before they were even recorded! Lens distortion really matters even in the digital age - and thank you for pointing that out. Where can I find an honest rating system of lenses and systems that will honestly rate based upon real world stuff like you have done in basically telling us to be wary of "fools arguments"? Thank you for your blog and your hard work. Dear Roger,whenever I read your stuff I am always reminded of the late Geoffrey Crawley who wrote reviews for the British Journal of Photography back in the day. Your no-nonsense, cut-to-the-chase, fanboy-averse approach is so refreshing, welcome and much needed. What a different technical world photography is this digital realm. There is so much potential misinformation and confusion regarding real-world IQ and how to achieve it and how to maintain it.
I got rid of a beloved, late, mint Nikkor 28/3.5 PC because the CA was just so outrageous that even after correction attempts in numerous software there was still what I can only describe as a white shadow where the red/purple fridge used to be. Your little article begins to explain why and points to a reality that what we use when we photograph is not just a sensor but a complete system (lens-sensor-electronics, etc)that often-times may deploy software manipulation (that is essenially what “firmware” is isn’t it?)even at the AD stage. Notwithstanding that, if we have a “perfect” sensor that requires no AD tricks to be “perfect” and we use a lens that captures an image full of distortion that must be corrected via software and will thus detract from the “perfectness” of the sensor, then what is the point of lauding the camera manufacturer because of having a sensor whose full potential cannot be realized due to deficiencies in the camera manufacturer’s lens line-up.
Where to find information on real, genuine and practical image IQ that takes such into consideration? For example, I have yet to read anything on DxO’s site that factors in the destructive effects of correcting for distortions like CA nor have they mentioned Nikon’s manipulation of the analogue signal before it is converted to digital. Whether this is still an issue or not a do not know. But I remember reading that astronomical photographers would not use certain Nikon cameras because the noise reduction process used effectively cancelled out some of the stars before they were even recorded!
Lens distortion really matters even in the digital age – and thank you for pointing that out. Where can I find an honest rating system of lenses and systems that will honestly rate based upon real world stuff like you have done in basically telling us to be wary of “fools arguments”? Thank you for your blog and your hard work.

]]> By: abib http://www.lensrentals.com/blog/2013/01/you-can-correct-it-in-post-but/comment-page-1#comment-27092 abib Mon, 14 Jan 2013 05:54:43 +0000 http://www.lensrentals.com/blog/?p=11605#comment-27092 That's why I sold my 24-105L and my 17-40mmL for a 14mmL mk 2. and sticking to the much better EFS 17-55mm f2.8 and 70-200mm L f4 i.s or f2.8L mk2. That’s why I sold my 24-105L and my 17-40mmL for a 14mmL mk 2. and sticking to the much better EFS 17-55mm f2.8 and 70-200mm L f4 i.s or f2.8L mk2.

]]> By: Eric http://www.lensrentals.com/blog/2013/01/you-can-correct-it-in-post-but/comment-page-1#comment-27045 Eric Sat, 12 Jan 2013 22:30:44 +0000 http://www.lensrentals.com/blog/?p=11605#comment-27045 Fantastic article - thanks for creating such a great blog. Fantastic article – thanks for creating such a great blog.

]]> By: WTV3D http://www.lensrentals.com/blog/2013/01/you-can-correct-it-in-post-but/comment-page-1#comment-26943 WTV3D Thu, 10 Jan 2013 20:36:46 +0000 http://www.lensrentals.com/blog/?p=11605#comment-26943 So true, great article. Thanks So true,
great article.
Thanks

]]> By: John http://www.lensrentals.com/blog/2013/01/you-can-correct-it-in-post-but/comment-page-1#comment-26929 John Thu, 10 Jan 2013 13:23:55 +0000 http://www.lensrentals.com/blog/?p=11605#comment-26929 Very interesting and informative post Roger, thank you. It makes me wonder (don't go testing this, hehe), if the sharper 24-70mm f/2.8 mark II, after correction, will be roughly the same resolution as the uncorrected 24-70mm f/4L. ;-) Very interesting and informative post Roger, thank you. It makes me wonder (don’t go testing this, hehe), if the sharper 24-70mm f/2.8 mark II, after correction, will be roughly the same resolution as the uncorrected 24-70mm f/4L. ;-)

]]> By: Daniel http://www.lensrentals.com/blog/2013/01/you-can-correct-it-in-post-but/comment-page-1#comment-26907 Daniel Wed, 09 Jan 2013 22:28:20 +0000 http://www.lensrentals.com/blog/?p=11605#comment-26907 Roger: understood and definitelly thank you for your efforts. Carry on the good work! Roger: understood and definitelly thank you for your efforts. Carry on the good work!

]]> By: Esa Tuunanen http://www.lensrentals.com/blog/2013/01/you-can-correct-it-in-post-but/comment-page-1#comment-26893 Esa Tuunanen Wed, 09 Jan 2013 15:54:26 +0000 http://www.lensrentals.com/blog/?p=11605#comment-26893 Like Volker said barrel distortion makes center of image "bulge" out needing some mutilation of also those pixels to sweep distortion under the rug. So resolution loss also in center should be expected. And just like he said software distortion correction is literally like pixels in some areas of image being compressed smaller and again streched in other places to reshape areas of image. So why should anyone think that process is lossless. You don't think same way from drawing some figure/pattern onto air balloon and then inflating balloon? Also multiple separate corrections should obviously cause more information loss because of multiple times that results of calculations are rounded up. Photozone did year ago MTF50 tests for few Samsung NX lenses both with and without distortion correction and also confirmed resolution loss. Simon, Raw Therapee doesn't do automatic distortion correction if you leave that option disabled. Like Volker said barrel distortion makes center of image “bulge” out needing some mutilation of also those pixels to sweep distortion under the rug. So resolution loss also in center should be expected.
And just like he said software distortion correction is literally like pixels in some areas of image being compressed smaller and again streched in other places to reshape areas of image.

So why should anyone think that process is lossless.
You don’t think same way from drawing some figure/pattern onto air balloon and then inflating balloon?

Also multiple separate corrections should obviously cause more information loss because of multiple times that results of calculations are rounded up.

Photozone did year ago MTF50 tests for few Samsung NX lenses both with and without distortion correction and also confirmed resolution loss.

Simon, Raw Therapee doesn’t do automatic distortion correction if you leave that option disabled.

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