R6mk2 dark edges to images?

[SimonDM]

My R6mk2 is about three months old. Until yesterday it's been pretty amazing (shutter count now around 1800 at a guess).

I now think I have a sticky shutter, but I'm not sure, so posting here in case I"m doing something stupid. This seems to be the worst kind of fault (if it is one), i.e. intermittent.

Yesterday I started a big project, to capture 360VR panoramas of my local golf course. that's 29 images per pano, three panos per hole, so around 1600 images, probably. Reviewing the five panos taken yesterday, every frame of the first three has a dark band down one side (images are mostly in portrait format). It's the side towards the baseplate of the camera (because the images are inverted through the lens).

For the last two panos, it isn't evident. Whatever was wrong seems to have cleared.

I'm using a Venus Laowa 15mm "zero D" f/2 lens at around f/8. It has some vignetting, but nothing normally on this scale. These below were both 1/5000th sec (aperture f/8) ISO 500. It's a fully manual lens (no electronics whatsoever), but it is R-mount and it was bought new with the camera.

I must add that the camera was accidentally left on mechanical shutter 'motor drive' (NOT the high speed electronic shutter!). I'm wondering if that has relevance. I turned it to single-shot for the last two panos, which are clean of the problem. I'm wondering presently if the first curtain was slowing down at the end of its travel, so the slit wasn't a constant width, but honestly it's really weird, and even looks a bit worse in the corners.

I can use this lens on a much slower shutter speed (and wind the ISO down a lot). I"m not keen to put an ND filter on it because of internal reflections - I know I'm going to have trouble with flare already!

Any thoughts welcome, particularly from people who know the R6mk2 well.

(the first image is from the pano's middle row)

From the first pano.From the upper ring of the first pano 

[stevet1]

SimonDM,

Do you have any other lens you can try?

You might also take the lens off and remount it.

Vignetting is usually caused by something blocking the light rays from hitting the sensor, like a lens hood or stacked filters or something. My thought was an ill-fitting lens.

Steve Thomas

[shadowsports]

Greetings,

What adapter are you using with the Zero-D?  I'm thinking its the lens, but test with something else as Steve1 suggests. Not sure because of the one-sided vignetting.  An RF lens might be best to evaluate with.

[SimonDM]

Hi both, thanks for the thoughts.

As far as I can tell, it's not vignetting of any sort. I'm using a specialist panoramic mount, which I have modified: the settings for pano mounts are camera & lens-specific, and, to be efficient on location I needed quick-release fittings throughout and I've replaced the tilt arm with one made specifically for the camera+lens (stops assembly errors in the field!). This setup was previously used successfully in the Canadian Rockies (Alberta) in June - no issues.

The lens has an RF mount - no EF adapter is necessary - although as I said it's fully manual (this is probably a good thing for panoramas). It has a single UV filter on it for physical protection, which has been on the lens since the day I bought it. Previously no issues.

Finally, I did five panos on Tuesday. The first three can't be stitched because of this problem, but the last two seem to be clean - only the lens's own corner vignetting shows (it's about 1/3 stop, but Enblend can handle it). And anyway I'm used to that, as it got a lot of use in Canada for ordinary landscape stuff.

I'm still baffled. I have other pressing tasks today (writing at 0618h after breakfast!), but I'll try to stitch one of the other two "good" panos over the week-end to see. I also took a few shots of blank walls in the house yesterday, to see if it would misbehave on demand. With the shutter on single-shot it was fine (that was the mode I mostly used in Canada also). I forgot to try "motor drive" modes - will do that later today if I get a sec. If I can catch it misbehaving I'll be pleased, as that at least means the problem is reproducible (and then it's Canon's problem!). 

Thanks once again for the thoughts -- keep them coming 🙂

Simon.

[SimonDM]

Update:

I've replicated the problem easily at home. Using 1/8000 as the shutter speed makes it even more obvious. It's nothing to do with the lens.

I suspect it's a slowing down/faulty first curtain.

Wex photo video, from whom I bought the camera and who are Canon dealers, have been helpful on the 'phone. The camera is well within the warranty period and Wex have a repair workshop. I'm hoping to get it to them today or tomorrow for evaluation.

Will post the outcome later. 

[shadowsports]

Thanks for the update.  We'll see what happens when you get the camera back.