Blackmagic Forum

For native L-Mount lenses, does the BMCC6K use the lens metadata to bake in lens corrections (vignette, color cast and distortions)?

I've come to realise short flange mirrorless mounts create acute angles of light at the sensor's and this leads to heavy vignetting and blue color shifts at the edge of frame.

I have run into significant problems with this when using BMCC6K with native L-Mount lenses like the 7artisans full frame Vision range.

For reference, this characteristic has been masked in mirrorless cameras to date because they use log profiles (where corrections are baked in).

Any ideas if lens corrections can be applied in camera or in Resolve?

That's quite interesting; one of the advantages of short flange distance mounts being touted, beyond flexibility, is better optical quality; though I can't see that when for many years a quite a large flange distance was required to clear a mirror shutter; prism block or/and ND filters, for film and video cameras; the PL mount being an example of this, designed at the tail end of film cameras, where the LPL has a far shorter flange distance and designed specifically for digital film.

CA on single sensors is dealt with by both internal electronic ALC and optical correction built into the mount, for B4 lenses; vignetting on the BMCC6K is possibly a result of a slightly smaller flange distance from some mirrorless, maybe? Perhaps not an issue for most FF cine lenses, that may have a larger coverage?

I'm not familiar with 7 Artisan lenses but aren't most of them mechanical lenses? Lens correction works on a per lens basis so there would need to be electronic contacts to tell the camera what lens was connected then the camera would need to have a profile that it would use for that lens. Even with electronic contacts the camera mfr. would need to care enough to design and or implement a lens correction profile which is highly unlikely for an outlier like 7 Artisans. Leica, Panasonic, Sigma, and Samyang (L-Mount Alliance) lenses likely offer correction profiles for L-Mount non raw shooting cams.

Beyond that the camera is primarily recording raw which means no lens correction is currently available with any lens, maybe in the proxy recording? Resolve seems the best bet. Some manufacturers release lens profiles for Photoshop but I have yet to see anything for DaVinci.

https://www.ttartisan.com/?LensProfile/167.html

Good Luck

Most of those corrections that are designed with the lens are specific to photography and not video.

Doing these corrections allow the lens to be designed with less expensive optical corrections. Making the kit lenses cheaper and appearing to perform better than they should.

Those in-camera corrections tend to be only applied in video to non raw video workflows.

In other words they are baked in.

Many of them are also brand specific. A lumix lens on an Olympus camera will only transmit basic geometry corrections but not complex things like chromatic aberration adjustments.

Your artisans lens probably has zero corrections on any camera by the way.

In-camera corrections like this generally aren’t considered useable in a raw video workflow. You can typically apply some basic geometry corrections in video later but a lot of the time corrections are based around the photographic features of the camera.

As soon as you pan a shot that has heavy geometry correction applied the gig is up anyway. So do you bake in a correction that can be seen or might change over time within a take, or leave it all to do later to taste? A shot that shows heavy chromatic aberrations at the beginning of the shot might not have the same high contrast at the end of the take. It’s hard to do these corrections over time, in changing circumstances and not have other artefacts.

JB

Thanks for the responses.
Lack of metadata/corrections is quite a significant limitation that I did not fully appreciate until now.

I have since replaced 7artisans with Sigma Art primes (older HSM design) which are optically corrected and give a more consistent image across the frame.