topic Canon R7 Weird image distortion during focus bracketing in EOS DSLR & Mirrorless Cameras

Canon R7 Weird image distortion during focus bracketing

MarkSturtevant — Sun, 20 Aug 2023 21:03:36 GMT

I am renting the Canon R7 to maybe buy. I have a lot of experience with hand-held focus bracketing for macrophotography. But with this R7 body, the images become slightly skewed back and forth in alternate pictures, so rendering a stack is impossible. Here are the settings:

R7 body, Canon 100mm f/2.8L with Raynox 250 diopter. The lens Image stabilization is turned OFF. The camera body stabilization is ON. f/5.6, 1/25 sec, ISO 100, LED continuous lighting, FOCUS BRACKETING: 20 frames, increment 5, electronic shutter, Exposure smoothing ON, Depth composite OFF (I stack in Zerene Stacker).

A similar problem was reported on a different forum from an Olympus camera. The feeling there was that electronic shutter was giving a rolling shutter effect, and the problem could not be resolved. I'm not sure about that explanation though. I am suspicious of the camera body image stabilization, but it's weird that this problem has not been widely reported that I've seen. I have a gif animation to show here, but I can't seem to get it to run. Here is the gif anyway if anyone wants to extract it and play it. Unfortunately the rental is supposed to go back tomorrow, so I will soon be limited in what I can actually try.

Re: Weird image distortion during focus bracketing

Waddizzle — Sun, 20 Aug 2023 12:48:11 GMT

Let’s try a test. Remove the Raynox and use a tripod. Disable Lens/Image Stabilization.

Re: Weird image distortion during focus bracketing

MarkSturtevant — Sun, 20 Aug 2023 15:14:13 GMT

Thank you for your quick reply! I will do that plus some other tests today.

Re: Weird image distortion during focus bracketing

MarkSturtevant — Sun, 20 Aug 2023 21:03:26 GMT

Update: I've run many tests with the R7 body, and with my old Canon body (t5i), all with the same lens. For the R7 I ran the focus bracketing tool in the R7 at various settings (namely focus increment, and whether the body IS was on or off. I don't see a way to control shutter speed since it defaults to electronic shutter, 30 frames / sec. With the t5i, I ran focus bracketing with the same lens by using the Helicon Fb tube which is a nifty thing that allows focus bracketing on a regular dslr camera (tho its much slower on the t5i). I ONLY get the skewing effect with the R7 body and ONLY if I am running f.b. while hand-held. If I use the R7 from a tripod, there is no skewing effect at all. The Raynox lens is not the culprit, btw, since when I remove it, I can get skewing if hand held, and no skewing if shooting from a tripod. The 100mm macro lens is not the reason either since the lens works perfectly on the t5i body. The lens IS is turned off for all of these recent runs.

My conclusion at this point is that the problem is a shutter rolling effect from the R7 body. While hand-held, there are incidental movements that are recorded due to limited sensor readout speed with the electronic shutter. This would be why consecutive images show a left-right skewing on one frame (thru horizontal movement of the camera), or a top-bottom compression in another frame (thru vertical movement of the camera). Wish I could show people the effect in the gif animation. If so, I could mitigate the effect with a slower shutter speed (taking fewer frames, and more slowly), but unfortunately I don't think I can do that while using the focus bracketing tool.

Re: Weird image distortion during focus bracketing

Waddizzle — Sun, 20 Aug 2023 23:44:37 GMT

First and foremost, congratulations on getting a lead on resolving your issue.

I did not understand what skewing meant. Not sure if I do, either. But, I knew shooting handheld images for stacking might not be good thing. The R7 has too much resolution for it. I would have thought using a tripod for focus stacking was a “must do.”

Re: Weird image distortion during focus bracketing

MarkSturtevant — Mon, 21 Aug 2023 04:05:23 GMT

The supposed gif animation above is three consecutive frames, run in a loop. But here it freezes up. Gifs run on some sites and not on others. To help visualize the distortions, imagine the above picture is being alternately skewed a little from left to right, then being compressed a little up and down.

Re: Weird image distortion during focus bracketing

Anonymous — Mon, 21 Aug 2023 04:24:37 GMT

The camera manual says to use a tripod when shooting in focus bracketing mode.

Re: Weird image distortion during focus bracketing

Anonymous — Mon, 21 Aug 2023 04:26:01 GMT

Yes, it is in the camera manual to use a tripod for focus bracketing shooting.

Re: Weird image distortion during focus bracketing

MarkSturtevant — Tue, 22 Aug 2023 02:56:48 GMT

Thank you. It seems to be the case.