Lens correction profile makes distortion worse at certain focales

[30898239]

Hello,

I have a Canon 100D with a Tamron XR Di II 17-50 f/2.8 lens and Lightroom CC 2015.8. Vignetting correction works fine, no problems there. Chromatic aberration correction seems fine too, no matter the focale.

Distortion correction is another topic. At 17mm it works perfectly well. The longer the focale, the worse it gets. I have a picture taken at 32mm and the distortion actually gets _worse_ when the lens correction is applied. There's a row of picture on the wall, so it's quite easy to see the barrel distortion. It is slightly worse after correction and definitely not corrected.

Any ideas what the issue could be?

[Just Shoot Me]

Un check the option to Enable Lens correction and see what happens.

[30898239]

That's how I know it makes it worse: by enabling/disabling the lens correction.

[Just Shoot Me]

Is there a badge at the bottom of the Lens correction section that looks like this.

That nmeans the lens has a built in profile that will correct for any distortion.

[30898239]

No, no such badge. It's a RAW file from a Canon 100D.

I did some further digging and it looks like the lens correction profile works quite well at 50mm too, barrel distortion is correctly removed. It's just for focales around the 32mm that the barrel distortion is not corrected or even worse, aggravated. I need to further dig out some example with square objects at different focal lengths to check that in detail.

[Just Shoot Me]

Also take a loo at this Adobe KB article.

Work with lens profiles in Adobe Photoshop, Lightroom, and Camera Raw

[30898239]

Thanks, I checked the link, quite interesting, unfortunately it did not resolve my issue.

I downloaded and installed the Adobe profile downloader (had a nice “back in time” feeling while installing Adobe AIR to be able to run it), to see if there's other profiles available for this lens, not luck.

At the moment I can only think of two options:

1. the profile is incorrect at certain focal lengths
2. EXIF data report an incorrect focal lengths and thus the profile in incorrectly applied.

[Just Shoot Me]

I see no XR lenses listed in the Supported Lenses page for Tamrom lenses. The only 17-50 f/2.8 is a SP.

Supported lenses

[30898239]

I think it's one an the same lens, it's just confusing. There's only one model from Tamron with “Di II” in the name and 17-50mm focal length. The lens itself has the following written on it, in this order: “ASPHERICAL LD XR DiII SP TAMRON AF 17 - 50 mm 1:2.8 (IF) ∅67 A16”.

It seems to be this lens, the picture matches at least:

http://www.tamron.eu/uk/objektive/sp-af-17-50mm-f28-xr-di-ii-ld-aspherical-if/http://www.tamron.eu/uk/objektive/sp-af-17-50mm-f28-xr-di-ii-ld-aspherical-if/

This being said, Lightroom behaves very strangely when it comes to automatically detecting the right profile for lens correction for this specific combination of camera and lens.

Pictures taken with this lens almost always show “17-50mm” under EXIF>Lens except when the focal length is 17mm: in that specific case, it shows “TAMRON SP 17-50mm F/2.8 DiII A16E”. Why is that? I can't explain this strange phenomenon.

When the focale is 17mm (and thus the EXIF shows the full lens name), Lightroom automatically selects the right lens under lens correction. The rest of the time, when the focal length is higher than 17mm, when I enable lens correction, lightroom says “unable to find a matching profile automatically”. I have to manually select “Tamron” under “Make” and only then does Lightroom choose “TAMRON SP 17-50mm F/2.8 DiII A16E”.

Having to manually select the right lens make is not that big a deal, at most it's an annoyance. The barrel distortion not being corrected, that a real problem though... I will try to upload a serie of test pictures in RAW format somewhere, if you want to test it.

[Just Shoot Me]

See if there is an updated firmware for the lens. I'm not sure how you would apply it even if there is. But Tamron should have instructions for that if there is an updated firmware.

[30898239]

TAMRON | TAMRON TAP-in Console TM TAMRON TAP-in Utility TM Online Help

Seems this lens is not supported for their firmware upgrade utility...

Thanks for all the help by the way, I'm learning a lot, didn't even know if was possible to upgrade the firmware of a lens.

[Just Shoot Me]

99% of all new lens systems are Fly By Wire in one way or another. So yes all of them have some type of operating system inside them. Which now every manufacturer calls the Firmware.