Learn to use flash by the weekend?

Hi,
I'm doing some (free) photography on Saturday for the First Lego League.
I have fast lenses (30mm 1.4, 100mm 2.8, 17-50 2.8, 70-200 2. but would like to try my new AF540-FGZ flash. Only problem is I haven't used it yet, besides 1 hour when I first got it. So between now and Saturday it is possible to learn how to use it? (I know flash is meant to be hard to master). I'm not talking about mastering it, just about how to use it/what settings in general for indoor shots of people relatively close to me (I'd say within 5 meters).
My plan is to take all the shots I need without the flash but afterwards (or in between) try some with the flash. So are there any basics bits anyone could share that would enable me to try it out? I have Matts manual (need to read it). Or is tonight and tomorrow night too short time?
Thanks,
Patrick.

You're right to be cautious, you're opening a can of worms there
If in doubt, put it on pTTL and bounce that bad boy off a ceiling or wall, especially if you have someone close, who might mess up the exposure.
Get as much ambient light in there as poss, by using a high ISO and(or) large (flattering) aperture, this will also help the flash to recharge and be able light your subject from a distant reflector.

Also if all shots are indoors make sure the subject is not to close to a wall as you can get some nasty shadows even sometimes when bouncing. Make sure what you bounce off of is white or you will get a colour cast from a coloured wall or ceiling. Otherwise for starters as the Darkmonk says use PTLL and the flash and camera should sort it out for you OK.
CHEERS Vic.

The only tip I can give as I am by no means a flash expert is - use a diffuser if possible. My results improved dramatically when I attached one to my AF-360 FGZ

Carl

Agree with the comments so far, if you can't bounce it because of the nature of the room, diffuse it.

Shoot in RAW so you have room to adjust the exposure in PP afterwards.

Great comments - Thank you
I have always been afraid of flash, simply because I don't understand it.

Thanks for the replies. It's in a hotel conference room so it'll be high ceilings so I can't really bounce it off the ceiling.

I'll give it a go in pTTL mode and buy a diffuser today
As I can't use the ceiling for bouncing should I aim my flash at the subjects or tilt it upwards still? I'm guessing at the subjects.
Do I shoot with settings as if I don't have a flash e.g. If I'm shooting let's say 1/200 second and f4, with flash should I change anything?

Thanks,
Patrick.

If you have a high enough ISO etc. you will still be able to bounce it.
When you turn on the flash, the camera will set the shutter to the sync speed.
I tend to use manual and find a nice darkish ambient setting, then use the flash to stop the local movement.
If people are dancing then a shutter of about 30th or even less, will help show some movement.
A diffuser per-se won't necessarily help. If it's small, it will still shine a point source onto the subject harshly picking up sweat etc.
A globe diffuser will fill the room with a little more light but if it's a big room it's likely to do nothing.
I often use a big white flexible bounce card (about A4) forget what it's called now. and fire straight up using the big reflector to light the subject, whilst also bouncing off the ceiling. But this can look a bit much in the wrong environment.
Most event togs, just blast their subjects straight-on and get away with it in an uninteresting, rabbit in the headlight sort of way. But it's safe.
A PTTL cable can have immediate desirable results, holding the flash at arm's length up high - just a lot more interesting. You can also bounce it down off the floor if it's a halloween party !

One small thing. You say 200th. sec. That's to fast for the flash. X sync on Pentax is 180th. sec. Unless you want to use high speed flash settings on your flash. As a "newbe" to flash don't go there yet.
A strap on 45 degree reflector with the flash straight up as the Munk says is a good idea and they're cheap to buy. You don't need a cable for PTTL it's part of the prog. on most new Pentax DSLR's. You don't say which model camera you have.
CHEERS Vic.

Hi Vic,

I have a K-5ii. I was only mentioning 1/200 second as an example.
So I should shoot at 1/180 or slower?

@Matt, when you say-
The biggest problems occur when you are trying to achieve ISO 100, f/11, 1/60s in that kind of environment and the flash has to slam out all its power. You'll get horrible cardboard cut out shots
Is the flash using more power as it's f11 so flash is trying to cover more area and it's darker cos low ISO?

Like I said, the camera will set itself down to the sync speed, unless you opt for manual, in which case you will need HSS set on the flash, or you will be shooting at low shutter speed for the ambiance and movement, in which case everything will be dandy on pTTL. like my photo. You DO need a pTTL cable if you want to hold the flash at arm's length using pTTL.
If you set you aperture to f11 or similar the flash has to do a lot of work to expose properly and may not be able to reach the sensor with enough power after bouncing around the room. The card board cutout is due to the fact that the subject will be entirely lit by the flash and the room will either be dark behind or filled with ugly white flash and shadows. As I said, set the camera to be showing a pleasing amount of ambient light then use the flash to help out/fill-in/stop movement locally, like my photo

Darkmunk. I think we are at cross purposes. when I said you don't need a cable for PTTL I didn't mean you don't "NEED" a cable for PTTL. What I meant was if the flash is on the camera PTTL works. Of course if you want the flash off of the camera you need a cable but I just thought that might be a bit advanced for a beginner with flash.
Pa. (Name)? Yes you should shoot at 180th. sec. or slower. When you get a bit more experience you can try high speed flash.
Don't forget to set your white balance to auto so it can balance out the combination of flash and whatever the indoor lighting might be. (normal bulbs, fluorescent whatever colour they may be) etc. The best thing for this is trial and error. Get there early and try different WB settings to see which is best.
CHEERS Vic.

Just one simple hint; whatever you do, stay away from auto ISO.

Your camera will try to expose for ambient light opening the aperture of the lens, reducing the shutter speed and cranking up the ISO to stupid values.

The latter results in an increase of reach of the flash (positive side effect). What is often forgotten is that there is also a minimum flash distance (in pTTL and auto-thyristor modes) of around 10% of the maximum. Overexposure can be the results if the subject is too close.