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Thread: Batis 85: correcting distortion, etc.

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    Batis 85: correcting distortion, etc.

    Since Adobe released the lens profiles for the Batis lenses, it's been possible to open and correct Batis RAW files in ACR. I decided to use one of the RAW files Guy was kind enough to supply here. (Thank you, Guy.) It is an interesting file, because it is blazingly sharp, even though it was shot wide open, at f1.8. It is full of fine detail. So, it presents us with a good way of seeing what happens to resolution when distortion is corrected.

    Click on images if you like to see them larger. The differences are small.

    First, from an uncorrected TIFF, using my typical initial settings, at 200 percent:

    Click image for larger version. 

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    Next, with the distortion profile applied, same settings otherwise:

    Click image for larger version. 

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    Then, no distortion correction, but a horizontal level correction:

    Click image for larger version. 

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    Next, with both distortion and level correction:

    Click image for larger version. 

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    Finally, with distortion and level correction, plus increased deconvolution sharpening:

    Click image for larger version. 

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    I'm not sure if the differences will be visible to you in these jpegs, but they are definitely visible in the TIFFs. I would summarize them this way:

    1. Applying distortion correction visibly decreases sharpness at 200 percent. (At 100 percent, it is hard to see, but slightly visible.)

    2. Applying horizontal level correction decreases sharpness also, possibly a bit more than distortion correction.

    3. Applying both horizontal level and distortion correction isn't noticeably worse than doing just one of those corrections. Resampling is resampling, for the most part.

    4. Applying both corrections, then moderately increasing deconvolution sharpening, restores most of the sharpness.

    I almost always do some kind of horizontal level correction. For the purpose of printing, I usually preview my files at 50% or 66%, not 200%. One other thing: the original file is full of moire. To knock that down, I might shoot at around f11, which would cause some diffraction. This could be partly reversed with good sharpening technique.

    Others have predicted these results, and made similar tests. I wanted to check this lens in particular, and see how things might come out with my work flow.

    --d
    Last edited by davidstock; 31st July 2015 at 13:03.

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    Re: Batis 85: correcting distortion, etc.

    Quote Originally Posted by davidstock View Post
    Since Adobe released the lens profiles for the Batis lenses, it's been possible to open and correct Batis RAW files in ACR. I decided to use one of the RAW files Guy was kind enough to supply here. (Thank you, Guy.) It is an interesting file, because it is blazingly sharp, even though it was shot wide open, at f1.8. It is full of fine detail. So, it presents us with a good way of seeing what happens to resolution when distortion is corrected.

    Click on images if you like to see them larger. The differences are small.

    First, from an uncorrected TIFF, using my typical initial settings, at 200 percent:

    Click image for larger version. 

Name:	bldg.jpg 
Views:	40 
Size:	954.7 KB 
ID:	93836

    Next, with the distortion profile applied, same settings otherwise:

    Click image for larger version. 

Name:	bldgcorrect.jpg 
Views:	35 
Size:	274.2 KB 
ID:	93837

    Then, no distortion correction, but a horizontal level correction:

    Click image for larger version. 

Name:	bldglevel.jpg 
Views:	42 
Size:	937.8 KB 
ID:	93839

    Next, with both distortion and level correction:

    Click image for larger version. 

Name:	bldglevelcorrect.jpg 
Views:	40 
Size:	903.0 KB 
ID:	93838

    Finally, with distortion and level correction, plus increased deconvolution sharpening:

    Click image for larger version. 

Name:	bldgall&sharpen.jpg 
Views:	28 
Size:	262.6 KB 
ID:	93840

    I'm not sure if the differences will be visible to you in these jpegs, but they are definitely visible in the TIFFs. I would summarize them this way:

    1. Applying distortion correction visibly decreases sharpness at 200 percent. (At 100 percent, it is hard to see, but slightly visible.)

    2. Applying horizontal level correction decreases sharpness also, possibly a bit more than distortion correction.

    3. Applying both horizontal level and distortion correction isn't noticeably worse than doing just one of those corrections. Resampling is resampling, for the most part.

    4. Applying both corrections, then moderately increasing deconvolution sharpening, restores most of the sharpness.

    I almost always do some kind of horizontal level correction. For the purpose of printing, I usually preview my files at 50% or 66%, not 200%. One other thing: the original file is full of moire. To knock that down, I might shoot at around f11, which would cause some diffraction. This could be partly reversed with good sharpening technique.

    Others have predicted these results, and made similar tests. I wanted to check this lens in particular, and see how things might come out with my work flow.

    --d
    So in conclusion do you feel the results of the 85 Batis after distortion correction is negligible in normal printed sizes (which usually correspond to what you'd see at 33-50% zoom on a non-retina screen?)
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    Re: Batis 85: correcting distortion, etc.

    I'll bet the profile corrections will be a good deal better once DxO has them available for the Batis.

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    Re: Batis 85: correcting distortion, etc.

    Quote Originally Posted by HiredArm View Post
    So in conclusion do you feel the results of the 85 Batis after distortion correction is negligible in normal printed sizes (which usually correspond to what you'd see at 33-50% zoom on a non-retina screen?)
    Yes. My experiments suggest to me that the loss from distortion correction will be invisible at normal printed sizes.

    It's a little disturbing to be reminded that ANY pixel remapping in ACR knocks a percentage off a lens' resolution. I hate to pay a lot of money for a lens and see it lose anything.

    But the Batis 85 starts with a lot of resolution. And correcting its distortion seems to cause less loss than a simple horizontal level correction. That puts things into perspective (!) for me. Maybe Zeiss and Hasselblad know what they're doing with these new lens designs?

    I considered canceling my Batis 85 pre-order when I saw so many curved lines (that are supposed to be straight) showing up in online sample jpegs. But now that I've experimented with corrected RAW files, I think I'm gonna stay with my order.

    --d

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    Re: Batis 85: correcting distortion, etc.

    David I just get t home after 3 weeks on the road so I will try and get out there with some new samples.
    Photography is all about experimentation and without it you will never learn art.

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    Re: Batis 85: correcting distortion, etc.

    Quote Originally Posted by davidstock View Post
    Yes. My experiments suggest to me that the loss from distortion correction will be invisible at normal printed sizes.

    It's a little disturbing to be reminded that ANY pixel remapping in ACR knocks a percentage off a lens' resolution. I hate to pay a lot of money for a lens and see it lose anything.

    But the Batis 85 starts with a lot of resolution. And correcting its distortion seems to cause less loss than a simple horizontal level correction. That puts things into perspective (!) for me. Maybe Zeiss and Hasselblad know what they're doing with these new lens designs?

    I considered canceling my Batis 85 pre-order when I saw so many curved lines (that are supposed to be straight) showing up in online sample jpegs. But now that I've experimented with corrected RAW files, I think I'm gonna stay with my order.

    --d
    If it doesn't work out then the 90 Macro seems to be corrected very well too. Maybe it's a better fit for you.
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    Re: Batis 85: correcting distortion, etc.

    This jives with my experience with the S lenses and profile correction. With very good, very sharp lenses, profile correction can do more harm than good. A good example would be the 120mm APO macro. The distortion is nearly imperceptible, as is CA. Turning the lens correction on only has the effect of shifting the pixels a slight amount, lowering the microcontrast a tiny bit. In more extreme conditions, these corrections can cause more significant problems. Recently I went back to edit one of my streetlight photos, and noticed that there was quite a bit of color fringing. I turned off the "remove chromatic aberration" and profile correction, and it disappeared. This is a special case since it was around out of gamut streetlight, but it is a very clear example of digital correction doing more harm than good. I am attaching 2:1 screenshots. Please note, however, that I missed the focus in the dark, so they are not as sharp as the lens is normally. You will not see a difference in sharpness between the two versions, but that difference is clear in tack sharp images.


    In lenses with more distortion, the trade off may be worth it. I guess with the 85mm being at 3 percent or so, it may make sense to keep it on if you are photographing buildings and as long as it does not do some weird fringing correction, but personally I would prefer lenses that are fully optically corrected, rather than reliant on digital correction. I am currently looking at a longer lens for the A7s and A7rII, and I am leaning towards the 90mm macro. I like the design and reported performance of the batis, but I am a bit put off by the distortion.

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    Re: Batis 85: correcting distortion, etc.

    Actually, I am not sure if it is clear in the attached images...I think they were downsized. But in the originals, the image with the correction has a very clear blue line right under the streetlight, and without correction, the photo looks more natural.

    edit to attach the full image, for scale.

    Click image for larger version. 

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    P.S. The odd shape of the streetlight glow is from snowy haze in the air...in clear air the glow is very circular and typical. See my website if you are curious. A lot of the streetlight photos were taken with the 120mm...
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    Re: Batis 85: correcting distortion, etc.

    Have any of you using Adobe's profiles tried using the profiles available with DxO Optics Pro 10?

    I've compared the two, and I've always chosen the DxO version. Perhaps it's because they develop their profiles for each camera/lens combo instead of the lens by itself. The results seem more uniformly sharp without the "profiled lens look".

    The camera/lens combos they support isn't thorough, especially when using legacy lenses with adapters. But for native FE mounts, IMHO the profiles are superior.

    re: The Batis line - nothing yet in their database, but in my experience they are usually quite quick with supporting new lenses.
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    Re: Batis 85: correcting distortion, etc.

    Quote Originally Posted by dandrewk View Post
    Have any of you using Adobe's profiles tried using the profiles available with DxO Optics Pro 10?

    I've compared the two, and I've always chosen the DxO version. Perhaps it's because they develop their profiles for each camera/lens combo instead of the lens by itself. The results seem more uniformly sharp without the "profiled lens look".

    The camera/lens combos they support isn't thorough, especially when using legacy lenses with adapters. But for native FE mounts, IMHO the profiles are superior.

    re: The Batis line - nothing yet in their database, but in my experience they are usually quite quick with supporting new lenses.
    I actually do this myself but you're correct in that there's no profiles yet.
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