5D MKII automatically changes aperture when filming

Hey POTN.

As the thread title says, my 5D MKII automatically sets the aperture when filming, if it's bright.

I tried filming in AV instead of M, but it still does it. Does anyone know what to do about this?

It's annoying I can't film @ 1.4 with my 50mm, and it automatically sets it higher so I don't get that much bokeh.


Help would be appreciated.

As I don't have that model, I'm not sure if this was something that was addressed in the more recent firmware upgrade?
Do you have the latest firmware?

But of course, if it's sunshine you'll never be able to use f/1.4, not even at ISO 100. You can't shoot movies with shorter exposure time than 1/4000, and f/1.4 in sunshine at ISO 100 requires something like 1/12800 or so.

Yeah I have the newest firmware, and not even when I shoot on ISO 50, it can.

It's just weird, since it doesn't have to be bright sunshine. I was filming a set for a TV series in a basement with only some colored lamps, and it kept changing the settings everytime i pressed record.

It's not broken, I'm sure theres a solution for this.

Please tell me exactly what you set up (mode, ISO, aperture - whatever), and I'll see if my 7D does the same.

Well, for an instance when I film outside the window, I film at ISO 50, shutter 100 and F/1.4

I remember when the 5D2 was first released, there was an issue similar to this but I don't recall the details. You would probably find out more if you posted this in the video section.

You can't film at ISO 50. I have the latest firmware and ISO Expansion mode turned on, and when in video mode you can only shoot at ISO 100+


I believe you have the camera in "Stills + Movie" mode and then have it in "Exposure Simulation" - it will let you record a movie from that position, but it does weird things to the aperture. Put it in "Movie Mode" not "Exposure Simulation" and try again. ISO 100 should be the only one available and the aperture should lock.

But outside the window, in daylight, at ISO 50 would require f/11 when using 1/100s shutter speed. Or f/16, if it's as said above that ISO expansion isn't used in video mode.
Something will have to change, or you'll get horrible overexposure.

If the OP wants to film at ƒ/1.4 in daylight he'll need to purchase an ND filter.

JonK wrote in post #10956747
If the OP wants to film at ƒ/1.4 in daylight he'll need to purchase an ND filter.

English isn't my native language, so I'm sorry, but what is an ND filter?

JonK wrote in post #10956697
You can't film at ISO 50. I have the latest firmware and ISO Expansion mode turned on, and when in video mode you can only shoot at ISO 100+


I believe you have the camera in "Stills + Movie" mode and then have it in "Exposure Simulation" - it will let you record a movie from that position, but it does weird things to the aperture. Put it in "Movie Mode" not "Exposure Simulation" and try again. ISO 100 should be the only one available and the aperture should lock.

Tried following your instructions, but it still does it. I've uploaded the result to youtube, you can see it here (it might still be converting though):

http://www.youtube.com​/watch?v=ATz1k28nDLU

Make sure you have the latest firmware on your camera and that you are in M mode. Av mode will automatically change the aperture for a proper exposure. Manual mode will allow you to over or under expose and won't change your settings based on incoming light.

Ferosso wrote in post #10957115
English isn't my native language, so I'm sorry, but what is an ND filter?

ND=Neutral Density.

Take it off "Exposure simulation". Second menu in the live view set up.

That helped! Thanks.