Defeating Auto Iris-Z1U

[Bill Ward]

I use the exposure compensation function a bunch...I've mapped it to a short cut button, and use the dial to adjust up and down from -7 to +7.

Here's my question: This still utilizes auto iris. I've tried putting the camera in manual and lock modes, and hitting the "iris" button on the camera to then adjust the exposure with the front dial. But, I'm noticing in all of these modes, there still appears to be something riding some kind of exposure control...and I can't seem to get it to stay locked at one F-stop during a pan from lighter to darker.

Any ideas what I'm missing?

[Khoi Pham]

You must also put gain and shutter on manual.

[Bill Ward]

Wow. So, all this time when I've been in manual iris...it's been diving into +9 and +18 automatically, regardless of what the front gain switch is positioned at?

That's whacked. What's even more whacked is how dark the video is now.

Thanks for the heads up!

[Khoi Pham]

Yep, pull out some old video, use your remote control and hit "data code" button, it will show you all the info like gain, shutter, apperture, you will see that whenever you adjust the apperture, your shutter or gain will adjust accordingly, to control the Z1 in manual mode, everything has to be in manual, if you just put apperture in manual, then it is called a aperture priority mode where the gain and shutter will adjust accordingly.

[Boyd Ostroff]

Originally Posted by Bill Ward

Wow. So, all this time when I've been in manual iris...it's been diving into +9 and +18 automatically, regardless of what the front gain switch is positioned at?

I don't think that's entirely true. I never use auto anything on my Z1, so it's not a feature I've paid attention to, but I believe there's a menu setting which will limit how much gain the camera will add when you have it set for auto.

[Alec Moreno]

Yes, going full manual should lock down the iris, but there is still a very subtle shift that can occur in the Z1/FX1 when panning/tilting from a very dark to a very light subject (or from light to dark). I've never noticed this shift when shooting, but it shows up after capturing the footage to hard drive very clearly...as if I had dialed the iris up or down a notch mid-shot. However, playing back the original tape in the camera shows that the manual settings do not change at all.

The culprit is having the automatic exposure speed set to "fast." I know...the automatic exposure settings should not play a role when in full manual mode, but I'm telling you that it does. After discovering this, I set the automatic exposure speed to "slow" and I have not seen the effect again. I suspect that the brightness still does drift a bit, during these particular shots, but the effect is essentially unrecognizable, given that the "drift" happens slowly as the lighting conditions in-frame change drastically during this time.

Alec Moreno
http://www.1Day1ShotProductions.com

[Alec Moreno]

Using the auto exposure override, as the original poster mentioned, does have its place. In some cases though, it can be better to simply limit the auto gain and auto iris by adjusting the settings within a picture profile. The three available automatic iris limits are F4, F6.8, and F11. The three available automatic gain limits are 0db, 6db, and 12db. Toying with these settings can give you a desirable shot...when going auto is warranted of course.

Here's another cool feature...
The auto gain limit, iris limit, and automatic exposure shift that you set in a picture profile will still apply if you put the camera in spotlight or backlight mode. If you also set the auto exposure override feature to one of your assign buttons, then you'll be in a better position to nail some of those continuos shots where you would normally have to gain up manually (and end up with a sharp brightness shift in the footage).

There's no replacement for knowing how to shoot in full-manual, but certain shots can be better adjusted by the camera than by us.

Alec Moreno
http://www.1Day1ShotProductions.com