Vignette issue - lens shade?

[antigallican]

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Hi

I am new to Q but not to Leica. I've discovered a vignetting issue - I think it's caused by the lens shade and seems to be automatically cleared away by the camera profile in LR but not Capture 1. The pictures attached are the same one processed in LR, one in C1. I wonder if anyone would like to comment on it please. Please forgive the cr@p photo - trying to get birds in flight on a hill. But the problem can be clearly seen in the pictures, hence me choosing this one in particular. Thanks

 

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[Bart van Hofwegen]

Lens corrections are needed for the Q's RAW files, they are part of the package so to speak. What you see in the first image is a rendering without these corrections. Geometry, vignetting (and CA, I think) corrections are present in the profile that is embedded in the RAW file, but also in Adobe's profile. But not all RAW converters apply these corrections automatically, some do not even recognize them. On the other hand, in Adobe you cannot switch them off. I am not familiar with Capture 1 but it would surprise me if it did not have the option to apply a correction profile for the Q.

[EUSe]

The issue occurs at 28 mm, especially if you are using UV or polarising filters - this is why I take off the lens shade for wide angle shots. The problem may also occur without the lens shade if you are not using ultra-thin filters.

Edited February 5, 2018 by EUSe

[frame-it]

in C1 try switching the "Camera Metadata" option on when you import the files..and see what it does.

[antigallican]

Thanks for replies all

[Bart van Hofwegen]

The issue occurs at 28 mm, especially if you are using UV or polarising filters - this is why I take off the lens shade for wide angle shots. The problem may also occur without the lens shade if you are not using ultra-thin filters.

 

I always shoot at full res 28mm, with the shade on (but no filters), and I never see this vignetting, unless I use a RAW converter that does not process the opcodes programmed into the camera profile. In fact, the dark corners are also there if you take the shade off...  What I see above is exactly that, not the lens shade in any way. A program such as FastRawViewer also shows the file without correction, including the black corners. But if you use Adobe LR or ACR, you will never see this at all. The solution is to find a way for Capture 1 to obey the lens correction needed for the Q. It is needed by design, the lens could be kept small and light by this software tweak.

 

*edit* I see another reply is added as I typed... As I said, I am not familiar with C1. Good luck!

Edited February 5, 2018 by Bart van Hofwegen

[HighlandK]

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I always shoot at full res 28mm, with the shade on (but no filters), and I never see this vignetting, unless I use a RAW converter that does not process the opcodes programmed into the camera profile. In fact, the dark corners are also there if you take the shade off...  What I see above is exactly that, not the lens shade in any way. A program such as FastRawViewer also shows the file without correction, including the black corners. But if you use Adobe LR or ACR, you will never see this at all. The solution is to find a way for Capture 1 to obey the lens correction needed for the Q. It is needed by design, the lens could be kept small and light by this software tweak.!

Thanks, this makes absolute sense. Always good to learn something extra.

[antigallican]

Yes I'm sure Bart's answer is correct - I just can't find an answer within C1. I've written to C1 and posed the question. When (if) they give an answer I'll post it here.

[pico]

The sensor sees more than standard PP software might reveal. There was a utility that would reveal the hidden pixels in the border of the sensor. I wonder if your software isn't simply trying to he honest, to show all pixels?

.

[Bart van Hofwegen]

The sensor sees more than standard PP software might reveal. There was a utility that would reveal the hidden pixels in the border of the sensor. I wonder if your software isn't simply trying to he honest, to show all pixels?

.

There are indeed pixels on the sensor that not make it to the final image, but that is not what you see here, this is simply the limitation of the imaging circle of the lens, producing black corners. The imaging circle is a tad smaller than the sensor. But because the lens also produces a fair amount of geometric (barrel) distortion, the corners are "pushed out" when this is corrected in software (inside or outside the camera). Part of the correction is also a bit of cropping, I think.

 

The pixels you refer to can be the edge pixels that are not included in the image directly but are used to facilitate the debayering of the RAW file (look it up on Google if you really want to know, but it is of little use to photographers). Some cameras also include a slice of "dark" pixels. These are covered so they never see any light (sad isn't it...) and can be used to calculate the black level, among other purposes. The photon wells in the sensor do contain some spurious photons after exposure, even when completely dark, due to all sorts of effects. These dark pixels can be used to count those, calculate an average (the black level) and subtract that form all the "real" pixels to get a cleaner image. This is an oversimplified explanation, again look it up if you want, but again, it is of little use to photographers, although slightly more so than the edge pixels.

[antigallican]

Thanks for the technical explanation, Bart.

 

Here's the Phase 1/Capture 1 official response - which doesn't substantially contradict Bart's explanation.

<<

Hi John,

 

The Lightroom version is cropped to avoid the vignette.  You can actually see that not all birds are visible.

If you are working with Raw... in Capture One make sure the manufacturer profile is applied in the lens correction tool and that distortion is set to 100%.

Best regards,

Phase One Technical Support>>

Edited February 6, 2018 by antigallican

[uffehagen]

 

Thanks for the technical explanation, Bart.

 

Here's the Phase 1/Capture 1 official response - which doesn't substantially contradict Bart's explanation.

<<

Hi John,

 

The Lightroom version is cropped to avoid the vignette.  You can actually see that not all birds are visible.

If you are working with Raw... in Capture One make sure the manufacturer profile is applied in the lens correction tool and that distortion is set to 100%.

Best regards,

 

Phase One Technical Support>>

 

 

The tool in C1 you are looking for is under Base Characteristics where you can use a Leica created profile or a generic

[Mike_HNL]

I always shoot at full res 28mm, with the shade on (but no filters), and I never see this vignetting, unless I use a RAW converter that does not process the opcodes programmed into the camera profile. In fact, the dark corners are also there if you take the shade off... What I see above is exactly that, not the lens shade in any way. A program such as FastRawViewer also shows the file without correction, including the black corners. But if you use Adobe LR or ACR, you will never see this at all. The solution is to find a way for Capture 1 to obey the lens correction needed for the Q. It is needed by design, the lens could be kept small and light by this software tweak.

 

*edit* I see another reply is added as I typed... As I said, I am not familiar with C1. Good luck!

I wonder if you took a picture with with DNG/JPG capture option if the vignetting would occur with the DNG, but not with the JPG, due to internalized processing within the Q.

 

 

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[Bart van Hofwegen]

I wonder if you took a picture with with DNG/JPG capture option if the vignetting would occur with the DNG, but not with the JPG, due to internalized processing within the Q.

 

The DNG always holds uncorrected data, the out-of-camera JPG always has the correction applied by the camera firmware. The DNG also includes what is called an "opcode", a set of instructions for correction, that most raw converters such as Adobe's Lightroom and ACR automatically apply. With Adobe, there is not even a way to turn this off. But if you open the DNG in tools such as FastRawViewer, RawDigger or RPP, then you see the image stored in the DNG without correction.

[Steameduck]

It is actually an design flaw of the Q. The lens is actually 23.3mm focal length and not covering the whole sensor. The correction profile is embedded in the DNG to crop the image and get 28mm equivalent. Always enable the lens correction when processing the DNG files.

In a few words. The Q is not a real FF camera.

[jaapv]

I think this was discussed to death when the camera came out. Everybody has been shooting happily ever after.

In fact, it is not actual cropping, it is interpolating.

[jaapv]

It is actually an design flaw of the Q. The lens is actually 23.3mm focal length and not covering the whole sensor. The correction profile is embedded in the DNG to crop the image and get 28mm equivalent. Always enable the lens correction when processing the DNG files.

In a few words. The Q is not a real FF camera.

Common misconception. Instead of a flaw it is a deliberate design decision to reach a higher quality level.

[Bart van Hofwegen]

Common misconception. Instead of a flaw it is a deliberate design decision to reach a higher quality level.

Deliberate, yes, but for quality in small size and weight. As many designs show, top quality 28mm with a full 35mm image circle sure is possible, but none of them (Zeiss Otus anyone? ) are near the handsome size and weight of the Q's lens. Not even close. The pixels peepers who peep at edges may find some loss, but what are they looking at then? Photographs? Hardly. I am very happy with the quality of the Q.

Edited July 1, 2018 by Bart van Hofwegen

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Hallo,

Look here: Leica Q

[jaapv]

Indeed, quality, size and price are always trade offs and this is an elegant way to break the circle.