Thanks, guys and gals. I've been doing the keyboard equivalent of biting my lip. I understand you dSLR guys mean well, but from our point of view, you are Trolls. No different than a Nikon guy coming on your baord and trashing Canon. Just cut and paste this message "You can't do that with a P&S. Get a dSLR." There. I've saved you some time.
We are aware of the limitations of our camera but we are trying to maximize the performance of the camera we have.
Mnk, page 66 of the G6 manual.
"The fastest shutter speed for flash syncronization is 1/250 second. The camera automatically resets the shutter speed to 1/250 second if a faster shutter speed is selected."
I can't tell if this includes Tv and M or just Tv. This makes your EXIF information critical. If it shows 1/250 and flash fired, you should have a decent picture. If it shows 1/400 sec and flash fired, the shutter didn't syncronize with the flash.
Mnk, you remind me of myself before I took a photography class. I hammered the internet for at least a couple of hours a day for over a half a year trying to learn photography. I got some good pictures but many of them needed a lot of help and even more were junk. I was what we used to call "book smart". I took a photography class and it turned the world around. I still have much to learn, but at least most of my pix are usable. And now, when I mess up, I have an idea why. Anyway, I'm not that far ahead of you. I'm saying this to soften the next paragraph.
Your posts are frustrating. You have posted twice. The first time you used 1/2000 sec shutter speed. The second time you used f8 aperture. Both settings reduce the amount of light hitting the sensor and insure a dark picture. There are other issues, but first, especially on Manual, you have to balance available light, shutter speed, and aperture size. I drove race cars for many years and I have a habit of describing situations in race car terms. You are trying to make your car go around the turn faster than it can go. You will always crash. The dSLR guys are telling you to get a faster, more expensive car. We are trying to help you fine tune the suspension so the car you have will corner faster.
On Manual, you need to try settings, then half press to get a reading in the upper left corner of the LCD. If the reading is -2 or +2 and red, that means you are way out of specs and even with a flash it isn't going to work. If it shows underexposed, either open the aperture, slow the shutter speed, or raise the ISO unitl it is at least a white reading.
Since you are shooting moving objects, start with the aperture wide open and ISO 400. Then lower the shutter speed until the half press shows 0 exposure. Now you are exposed properly. You may have other problems, such as shallow depth of field and noise, but you have a starting point.