Wed 30-Sep-20 12:31 AM | edited Wed 30-Sep-20 12:33 AM by mklass
An interesting thing that I have learned using the TechArt adapter and a number of Sigma, Sony and Tamron e mount lenses: Since the lens is being used on a non-native camera, in-camera distortion correction is not available. So when you look at the raw file or an extracted JPG before processing, you see the inherent distortion in the lens.
At first I thought this was caused by the adapter, but I checked with Sigma, because the new 85mm f/1.4 DG DN Art is truly horrible looking before correction. When I asked Sigma about this, they said I needed to have distortion correction turned on in the camera, otherwise this is what you get:
That window is square and flat, it isn't a bow window. And the distortion continues well past just the edges. The top edge of the window blind should be straight.
I have never seen significant distortion on any of the Sigma Art lenses (and I have owned most of them) so this was truly astounding. In this case Sigma seems to have given up on good optical design and is relying on software to generate a decent image. (On the other hand, the Sigma 35mm f/1.2 DG DN Art is distortion free when mounted on a Z7 with the Techart adapter. Other lenses have moderate distortion.)
In discussions on Fred Miranda about the Techart Adapter, it was stated that even the great performance of Nikon Z lenses is significantly due to in-camera distortion correction. The 24-70 f/2.8 S apparently has 3%+ pincushion in it's uncorrected state, a threshold that is generally considered unacceptable. But the in-camera distortion correction generates a good NEF.
Some say this is an intent problem with mirrorless cameras. Is it? Does it matter that the lenses are less than perfect (sometimes far less) and rely on computer programming to make them good? Seems like cheating to me, especially when you pay a premium price for a lens. Both the 24-70 f/2.8 S Nikkor and the 85mm f/1.4 DG DN Art Sigma are premium priced. Attachment#1 (jpg file)
Mick "The difference between a professional photographer and other photographers is the pro doesn't show you the bad shots."
At first I thought this was caused by the adapter, but I checked with Sigma, because the new 85mm f/1.4 DG DN Art is truly horrible looking before correction. When I asked Sigma about this, they said I needed to have distortion correction turned on in the camera, otherwise this is what you get:
That window is square and flat, it isn't a bow window. And the distortion continues well past just the edges. The top edge of the window blind should be straight.
I have never seen significant distortion on any of the Sigma Art lenses (and I have owned most of them) so this was truly astounding. In this case Sigma seems to have given up on good optical design and is relying on software to generate a decent image. (On the other hand, the Sigma 35mm f/1.2 DG DN Art is distortion free when mounted on a Z7 with the Techart adapter. Other lenses have moderate distortion.)
In discussions on Fred Miranda about the Techart Adapter, it was stated that even the great performance of Nikon Z lenses is significantly due to in-camera distortion correction. The 24-70 f/2.8 S apparently has 3%+ pincushion in it's uncorrected state, a threshold that is generally considered unacceptable. But the in-camera distortion correction generates a good NEF.
Some say this is an intent problem with mirrorless cameras. Is it? Does it matter that the lenses are less than perfect (sometimes far less) and rely on computer programming to make them good? Seems like cheating to me, especially when you pay a premium price for a lens. Both the 24-70 f/2.8 S Nikkor and the 85mm f/1.4 DG DN Art Sigma are premium priced.
Attachment#1 (jpg file)