Sometimes I notice that we lighting a subject head on or from the front, there will be a shadow under the chin that is difficult to deal with. Sometimes eveything is else seems to be lit perfectly, except for a dark area under the chin. The dark area makes it look light the person has a light beard. I even notice this on tv sometimes. Does anyone have any input on how to deal with this? Even with 3 point lighting I sometimes notice this when the subject is being lit head on.

Typically that happens when your KEY light is set to high. Perhaps lowering it a small amount. Even an inch or 2 can make a difference. Of course if you need to have the light exactly where it is height wise then you can try a number of things to open up the "beard".
One you can try a small kicker light set up below the shoulder level of the talent very weak and or diffuse and aimed slightly upward to open up the shadow OR a reflector can do the trick in many cases. Either way be careful with its use. Not too much or it'll take away from the key and fill. You can use white foamcore or get some silver reflective material (shiny or dull) or if you want to warm it up a bit they have gold.
I'm sure there are other ways but right now I'm braindead.

Don:

Don do you mean shine the light head on below the shoulders? I''m not sure a reflector would help in this situation if being place head on, i'm not sure it would pick up either the key or the fill.

I've had very good luck with a reflector bouncing the main light. On another shoot we actually mounted an LED panel out of frame below and it did the trick. usually these odd situations happen when space is limited. Or outdoors when the suns in the wrong place. When I've done shoots in a large studio, the lights can be positioned properly.

Then again, there are subjects for whom having that part of the body in the shadows is actually better than having it fully lit. In fact, I read it in Jackman's book as a technique for lighting portly and aging subjects.

That's why I only shoot beautiful young people! Ha ha!
I started reading up on portrait photography lighting and found a bunch of useful info on angles, diffusion, color gels and lots of other stuff that can apply directly to video. All happened when one of my clients asked if I could do corporate portraits for their 12 executives since I had a decent camera. Worked out great and now I am offering that as a service. Seems lighting is one of those things that I will always be educating myself on.

First as mentioned don't shoot people like me with wrinkles below the head. That eliminates the problem. ;-)

Seriously,the use of the reflector should open the shadows nicely, It's a technique I learned almost 40 years ago doing stills. Portraits, models, even bands 1 200w flash on a 42 inch white umbrella and a reflector opposite of it - BAM! worked great. Anyway yes it will work. As for the light a soft light from below the chin level, I mean SOFT and SLIGHTLY below will also work. You must set that light carefully or you can run into trouble so thats why I recommend the reflector. It's fast, down and dirty and it doesn't have to be set quite as precisely as a light.
Again in front of and slightly below the subject tilt it up a bit to capture the fall off and open the chin shadows

Hey Robert, proper portrait lighting is really a lifelong adventure but the same rules from 40 years ago apply today. Keeping it simple and basic has always worked the best for me.

If you have a back light, then it's often possible to use this with a front reflector to get some light back up. Just move to a position just left or right of centre and use your hand to find the beam, then bounce it back.

As mentioned it may be advantageous to have the light fall off under the chin to keep it as a single item (when there are multiple chins!) If it is too hard a line, it's possible the key light is harder than it might want to be also. A softer key will create a more gradual falloff and wrap under the chin a bit more as well. I'd start with softening the key.

A bounce is indeed easier to use and more subtle than an instrument as an up-fill if more light is desired. If you are shooting a headshot, you can get pretty aggressive with how close you bring in the bounce, it can be literally just below frame and right in front of them if necessary. If you need more oomph out of it, you can set a light (I'd usually use a small tungsten unit on a dimmer) to pick up the value of the bounce. When shooting women I tend to use a lot of white bounce sources. Most actresses over 35 are well aware of this sort of thing and you often hear "here comes the world of white! I remember a time I didn't need to be surrounded by white cards" etc--they are generally joking as they appreciate every effort to make them look glamorous. In this instance we rarely use the concept of three-point lighting, more like indirect sources to avoid hotspots and to wrap the subject in a glow rather than a hot single source. An exception is when using a ringlight on the lens or equivalent for a high fashion look, where you don't need additional fill.

Thanks for the input everyone. I will try the reflector to see if that does the trick. This is for a waist up green screen shoot. I was using a pair of tota's and was shooting thru the umbrella instead of putting it in reverse and bouncing off of the umbrella. I was using a 500 watt bulb in each light. Everything else turned out great and the chroma key was perfect Do you think that shooting thru the umbrella contributed to the shadow problem? I was using a white umbrella.

Kevin,
Since it a greenscreen I would definately use a reflector to open up the shadows so as to keep any shadows falling on the screen and no I highly doubt shooting thru the umbrellas caused the shadow. Generally it's caused more by intensity of the light and placement of the light.

Don: wouldn't you agree that it's not the intensity of the light that causes shadows, it's the ratio of that light to other light sources in the scene?

I would go with placement and size/softness of source and level of fill light as the three factors that determine the definition and depth of a shadow. One could argue distance from source to subject but that is effectively a size factor. If this was to be considered in terms of a pattern on a wall, you would also factor distance from gobo to both source and shadow--in this case is the gobo is the chin so it's just a few inches from there to the neck.

My shoot yesterday was GS waist up too. The room was insanely small (about 10x12) but managed to stuff 2 32" softboxes on the 6x9 screen, a 24" softbox for the talent and a small backlight. Looked great as the keylight was about 3 feet back and eye level with the talent and right next to the camera. And since it was a dimmable light, we didn't blind the talent either! just set it to where he was comfy and adjusted exposure accordingly. The lights for the screen were adjustable too which was very helpful in getting the right balance between talent and screen.
It keyed in about 5 minutes right in FCP with no aftermarket plugins. Fun when It all comes together!

Going back to the OP, sounds like the height of the keylight is part of the issue. With keeping the softbox centered and eye level there wasn't an issue with shadows under the chin. Also the falloff of the softboxes kept any shadows from being cast on the screen even though distance from keylight to screen was about 8 or 9 feet!

Hey Charles, Yes, ratios mean everything but if the OP is like me I do as much with 2 and not more than 3 lights as I can. Gotta keep the kit lite (one man band) so I also carry a couple pieces of foam core (24x36) and a 100W light just in case.
When I did product stills back in the 70s generally my key light was a 4k and my main fill was a 2k then I'd light the highligts from there. Of course dulling spray was my friend as well but since we can't use that on people....
In a lot of cases the fill would be 1/2 the distances to the product as the key or vise versa but for people (learned doing portraits back in the olden days) the general rule was the fill was about 50% farther away than the key IF they were both the same power which was pretty common back then.
Anyway yep, ratios are everything. Maybe one day I'll update my lighting kit.

Regarding dimmers, one of the great bits of indie wisdom I found here was the recommendation for the Harbor Tools unit (http://www.harborfreight.com/router-speed-control-43060.html) at a whopping $20 that can handle up to 15 amps. I have four in my kit now and they work just fine. I'm a big believer in using dimmers for speed, especially with small crew--scrims are great to maintain color temperature and get you close but nothing beats a dimmer for tweaking. The only way to go for hair lights or other instruments hung high when time is of the essence.

Wow. Nice deal. There's actually a brick and mortar Harbor Freight not too far from me. I'll have to go check it out. For 20 bucks each how can you go wrong.
Thanks for the tip.

Those units are great. I have 4 of them and use them all the time.

Agreed! I use them all the time.
They are also great for controlling accent lights on background objects and dimming practicals.

Sometimes I notice that we lighting a subject head on or from the front, there will be a shadow under the chin that is difficult to deal with.

Start by adjusting you camera angle, all the similar problems that I see is caused by the camera being too low and shooting into the chin. The camera lens should be at the same height as the eyes, then tilt it down to frame the subjects, by doing this you'll hide or make less prominent the shadow on the chin. Shadows are important, that's what gives modeling and depth and the only way to control it is by correctly placing the key light.

With subjects with prominent double chin the camera should be even slightly higher. Also by getting the subject to look slightly upward the chin will stretch and make it almost disappear or become less noticeable.

Read some books on portraitures.

Nino thanks for chiming in. I stumbled onto your sight a few days ago when trying to find an answer to this question. It looks like a great resource and I am sure that I will be using it to gain more knowledge.