The Olympus Pen cameras offers a fair bit of versatility when it comes to customizing the settings when shooting movies.
For exposure, I was aware from what I had read that I could select aperture, shutter speed and ISO settings - but was stumped when even in A or M modes - - - the screen would brighten up when shooting the video and apparently not use the customizations that I had entered. The only setting that did work, was exposure compensation. And so for a while I used that to control the exposure or density of my video - - - mind the compensation was based on auto exposure.
You may presume like I did - that shooting in A, P, S, M mode would allow more manual controls than when shooting in Movie mode (icon with the old fashioned movie camera on your main mode dial). But it turns out that in all of those modes, exposure settings will revert to Auto - regardless of what they have been set to before shooting. That includes ISO settings. And so this creates another issue when you are wanting to control ISO in order to control noise. Even though it may appear that you can set your ISO settings - they are being overridden when actually taking the video.
Well, the only way that you can set the ISO is when in Movie Mode. But you may have tried this and noticed that all settings other than Auto ISO are greyed out and not usable. That is because even when in Movie Mode, you will need to set the shooting mode to Manual. To do this, press the OK button when in Movie Mode > select M in the first icon of the right vertical menu strip. You can then go down to the ISO icon and change the settings between 200 and 1600 ISO.
I was reminded of this when I received a comment on this video asking about the possibility of setting the ISO - City Night Lights - Olympus E-PL1 HD video - YouTube
I'm sure there are others that wonder this as well - and so I am posting my result.