Leica T lens corrections in dng question

[lukemather1]

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Hi,

I've been trying out a new Sigma 35mm DG DN on my Leica T but have found severe colour shifts in the unprocessed dng files which isn't present in the OOC jpgs and I am unable to correct sufficiently in Lightroom. I haven't seen anything like this with my Elmarit-TL 18mm, does anyone know of a difference in how lens profiles are treated in the dng files between Leica and non-Leica lenses?

Any suggestions would be much appreciated.

Thanks.

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[jaapv]

That is indeed quite severe lateral and longitudinal (both!) chromatic aberration - rather disappointing for this lens, I would return it. A lens profile won't help. Lightroom provides a slider to correct.

 

 

 

 

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[lct]

Curious that the aberrations are not present in the OoC jpeg files. I would try to remove the opcodes through DNG cleaner or same and see what happens.

[lukemather1]

Thank you for your responses.

I've tried playing with the sliders in Lightroom but haven't been able to fully correct the issue (I have no experience of this so could be missing something), it seems to only desaturate the relevant colours which with such severe shift it leaves an artefact behind.

Removing the opcodes in DNG cleaner and re-importing leaves no visible sign and seems to match the OOC jpg processing, as does opening the original file in RawTherapee. The only conclusion I can come to is that the raw image is fine but either Lightroom is misinterpreting something in the opcodes or they are corrupted by the camera/lens.

[jaapv]

What version of Lightroom are you using?

[lukemather1]

Lightroom Classic 10.2 and Camera Raw 13.2

[jaapv]

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In that case this is rather unexpected. I would report the matter to Sigma. 

[tommonego@gmail.com]

Can you still send it back to who you bought it from? What I don't like about Sigma, they design good lenses but every once in a while a stinker gets through QC. 

[frame-it]

but keep in mind the T firmware has not been updated for a very long time... so its more a body problem not a lens problem.

[lct]

Would be a body problem if the lens were a Leica. 

[ramarren]

On 4/20/2021 at 10:10 AM, lukemather1 said:

Hi,

I've been trying out a new Sigma 35mm DG DN on my Leica T but have found severe colour shifts in the unprocessed dng files which isn't present in the OOC jpgs and I am unable to correct sufficiently in Lightroom. I haven't seen anything like this with my Elmarit-TL 18mm, does anyone know of a difference in how lens profiles are treated in the dng files between Leica and non-Leica lenses?

Any suggestions would be much appreciated.

Thanks.

Welcome, dear visitor! As registered member you'd see an image here…

Simply register for free here – We are always happy to welcome new members!

That looks nigh onto unusable, to me. Do you have an out of camera JPEG of the same exposure? 

I can't imagine anything in the camera body that could cause so much apparent lateral chromatic aberration, and if the JPEGs are good, there's something seriously awry with the lens' injection of correction parameters for the DNG file. The body is just transferring whatever lens parameters the lens supplies into the DNG file, as far as I'm aware.  

Very curious situation.

G

[lukemather1]

Thank you all for your help. I've returned the lens and they've confirmed it's faulty, might stick with Leica for the time being!