HDR Video 5dmk2 question/problem

[tsbanking]

Hi Guys.
Please have a look at this video:
https://youtu.be/FSWpxwVWGCs
Why does it make that clicking sound and overexposes and than goes back to normal?
Also I thought in HDR video mode when not recording  its suppose to change from low to high iso every second or two to give you a preview. Mine doesn't.
Any help appreciated.
Thanks.

[cmccullum]

Try manual (m) mode.

[tsbanking]

Well, i need it to work in T mode...

[cmccullum]

From your video, it seems that your camera is trying to change the aperture to compensate for the exposure difference between the two ISOs, but can't keep up. Try M mode and see if  The problem goes away

[tsbanking]

Thanks, for your advice, it works fine in M, just trying to understand why it can't keep up.. I don't think its suppose to try to have correct exposure for both iso's, thats not what HDR is about. One of them supposed to be under or over exposed. What am I missing?

[cmccullum]

You're missing that you need to be in M mode.

Tv is shutter priority which means you set the shutter speed and let the camera decide other settings (aperture and ISO) to get proper exposure. The HDR video is cycling between 2 different ISOs so it's messing up the cameras auto exposure calculations.

Example:
Camera in TV
You set- Shutter speed 1/50
Camera meters lights in scene
Camera sets- f/5.6 ISO 100
Load ML HDR video
Set ISO at 100 & 800
At 100 ISO f/5.6 is fine as this is what the camera read
But when the camera meters at 800 ISO it's going to stop down the aperture to darken the image

Thanks, for your advice, it works fine in M, just trying to understand why it can't keep up.. One of them supposed to be under or over exposed. What am I missing?

You answered your own question here. It's not supposed to keep up, but in Tv mode you're saying that it should try to make a correct exposure

[tsbanking]

  I think I understand how it works now, but wouldn't it be better if:
in Tv mode HDR:
ISO set at 100 & 800
I set- Shutter speed 1/50
Camera meters lights in scene
Camera sets- f/5.6 ISO 100
Camera changes nothing at ISO 800, f stays at 5.6
IF what I'm shooting becomes under or over exposed f changes to whatever it needs to be to when it meters for iso 100 and stays like that at iso 800..
That way I don't have overexposed and underexposed parts if lets say I pan my camera outside on a sunny day- it would adjust F.
In M everything is set F,T and ISO so there is no way camera can adjust to changes.

[cmccullum]

 In Tv mode, the camera uses aperture and ISO to make correct exposure. If you change ISO (via HDR video) the camera will compensate to correct the exposure that is the point of Tv mode.

Given your example, the exposure would have to be correct at both 1/50 f/5.6 ISO 100 and
1/50 f/5.6 ISO 800. This isn't going to happen because each parameter will change exposure. To keep exposure the same while raising on value, another most be lowered and opposite. This is basic stuff.

Why do you believe you must have the camera in Tv mode?

Edit: I just reread your last post, and understand what you're saying, and that would be an interesting way of working, but it doesn't seem to be how HDR video works currently. Maybe some of the devs or anyone who knows about coding could chime in now on whether this is possible, but I don't think it is at all

[tsbanking]

We'll wait and see.
Thanks for your help! At least I understand the way it works now.