EOS R5 Mark II - Can AEB be set to change shutter speed between bracketed shots when in manual mode?

[ruthlevenstein]

I've recently picked up the R5 mark II and I can't seem to figure out how to set it such that when using AEB in manual mode, the aperature and ISO stay constant between shots and the shutter speed changes.  (I am shooting the moon and want to capture the craters.  All of my previous cameras would change the shutter speed which is preferable for me for these photos.)

[p4pictures]

There is no custom setting that changes the way the camera does auto exposure bracketing in manual mode. 

If you are in manual exposure mode, set the aperture you want and set the ISO to a fixed value. Then the camera will adjust the shutter speed to do the bracketing. If the ISO is set to AUTO, then the camera will use a combination of ISO and shutter speed to do the bracketing. 

The camera adjusts shutter speed as changes to aperture would result in different depth of field and that may make it harder to blend the photos later.

[ruthlevenstein]

I did set the aperature and the ISO to what I wanted, but I also need to set the shutter speed in manual mode.  For some reason the camera is changing the aperature instead of the shutter speed for AEB which is really frustrating ... I'm not sure if I missed a setting somewhere or not but the changing aperature is a big prolem for post production for exactly the reasons you noted above.

[p4pictures]

What is the shutter speed you have set for the photos? Do you have any restrictions on the range of shutter speed. 

For example, if you select a 15s shutter speed, and a +/- 2EV bracket the camera cannot do a 60s exposure for the image that is 2-stops over, so would change the aperture. 

I have now tried this with 3 different cameras EOS R6, EOS R6 Mark II and EOS R3 and they all work the same, adjusting shutter speed when using AEB in manual exposure mode with a fixed ISO value.

[ruthlevenstein]

This seems to be specific to the R5mII.  I have a 5DmIV and a 5DmIII (and a Sony alpha 7iii) and all of these cameras change the shutter speed in this scenario.  Only my R5mII changes the aperture.  It's really frustrating because I don't have the option of using anything except manual because I'm doing moon shots and the exposure is always wrong in anything except manual settings.

[kvbarkley]

The manual is unambiguous:

[ADP16508]

I had the same issue. I switched to Fv mode and set the SS to auto, while the aperture and ISO settings were manually set. It seems to work.

[ruthlevenstein]

The problem is I'm taking moon shots - the only way to get the exposure to the right neighbourhood is to set it on fully manual and actually set the ISO, shutter speed and aperature.  In every other camera I've had (including 5DmIV and a Sony alpa 7iii) when you use AEB in these settings the shutter speed is the one that changes, which is what I want.  For some reason, in the R5mII the camera insists on changing the aperature which is not right for this purpose ... URG!!!!   I still haven't found a solution to this.