Video Basics
 

Just got back from filming my first wedding today! Loved it! I've edited weddings before but never shot.

Some basic questions though I've posed before but didn't know how to properly ask:

What is the difference between iris, shutter speed, gain and nd filter? I know what the terms mean, but as far as in the quality of the video what do they mean? All I have really used them for is making the picture brighter or dimmer. I'm definitely not using them to their full potential, but which periods would it be more appropriate to use gain to make it brighter, my iris to make it brighter and my shutter speed to make it brighter?

When should I NOT use something in this way and how should I properly use it?

Thanks!!

I'll take a crack at this one. And someone correct me if I'm wrong. I'm sure others will chime in as well.

Keeping your iris open can give you a more shallow depth of field, especially when zoomed. A shallow depth of field really makes your subject stand out.

A high shutter will give you more crisp images with less motion blur, but isn't practical in low light. And some prefer a lower shutter speed for a bit of motion blur which can produce a more natural look. The film standard is 48.

Gain makes the image brighter, but your picture quality will suffer with the more gain you use. Don't use gain unless you have to. Of course in low light, you pretty much have to if you don't have enough light.

ND filter is great outdoors under sun light. My camera tells me when to use the ND filter. If you have an established shot and your cam is tell you to use the ND filter then use it. Boosting up the shutter won't be as good as using the ND filter under direct sunlight (and neither will closing the iris).

Tim pretty well gave you the explaination. Let me see if I can expand and further define.

ALL of those thing work hand in hand. Once you have set the proper exposure if you change 1 thing like iris you need to adjust the shutter speed, if you turn on an ND filter then you need to change either the iris and or shutter speed.

Now keep in mind that you need to set the right exposure first! otherwise you'll be going around in circles.
Also keep in mind that exposure has to come first before worrying about DoF. So if you want a shallower DoF you need to first set the proper exposure THEN open up your iris to get the Dof you desire THEN set the shutter speed to correct. So if you open the iris say 3 stops (say from f/8 to f2.8) then you need to raise the shutter speed 3 speeds from 1/60 to 1/250 OR whatever 3 full stops and/or speeds would be on your camera.

If you don't do that then you will either have very over or under exposed footage-neither of which is good.

I can't say for all cameras but generally and I know for sure on Sonys that if any of those settings (iris, gain, shutter) is not set to manual the camera will fall back to that setting and let it run in auto therefore no control over the camera.

Oh yeah last thing. GAIN. Generally the less the better but there are simply times when you need to add gain (low light wedding receptions are a good place to start) How much gain is a delicate thing. I try not to exceed +9 but I have gone as high as +15 on my Sony PD170s and it's been just fine. Of course if you're shooting HDV or higher you probably wouldn't want to go that high but if you add gain you can lower shutteer speed by and equal amount, or close the iris equally. While I would rather run at 1/60 at f/1.6 without gain there are simply times you can't avoid adding gain as you need the exposure. It's a fine line and takes knowing your gear and what you can and can't do with it.
Best advice is to play play and play somemore with your camera, try ALL the different combinations of shutter, iris, and gain, call it out so it's recorded and then when you load it in you know what you did and can see the differences.
HTHs

Could I just add to Don's masterly description the comment that to produce lower priced cameras the trend has been to use smaller chips? This has a direct effect upon the relative DoF which can be achieved under any conditions.

My guess is that the OP isn't ready for a detailed explanation but I know there is at least one elsewhere in this forum if he is interested when his understanding of the basics is better founded.

It's a pity that more people aren't as interested as the OP - for the better we understand the fundamentals the better we can use automation.

I have to agree with Philips point about using Auto after learning the fundamentals.
I spent years forcing myself to shoot in manual mode, which was great for learning, but there is nothing wrong shooting in Auto as long as you understand how the camera is going to calculate the settings.
I struggled with remembering how to set the iris to get the Dof I wanted for a while, but the thing that really helped me was getting into still photography. For some reason, it only took a few weeks with a DSLR to give me a much better understanding of the fundamentals than I had learned in years of shooting video.