Fill-Flash Question

[Celestar]

I am using a Nikon F4 HP with a sync speed of 1/80. If I were to use a manual flash (say Metz), I like to know how to use fill-flash technique.
I understand the chosen shuttle speed should be less than 1/80, in order to get the flash to be effective. Suppose I take a shot at f2.8, shuttle speed is 1/60. Should I then be checking to see if the flash can reach this distance (through looking at the flash table display on the flash) to make sure that fill is sufficient. How to I adjust the amount of flash output? Is that possible.
Second question is what would happen if I chose the shuttle speed to be over 1/80, say 1/125, what would happen. Also, when I use flash in this manner, do I have to adjust the shuttle speed mode to X. I suppose not, because by then, I will be lock into 1/80.
I hope someone can help me on this.
Many thanks

[another view]

I am using a Nikon F4 HP with a sync speed of 1/80. If I were to use a manual flash (say Metz), I like to know how to use fill-flash technique.
I understand the chosen shuttle speed should be less than 1/80, in order to get the flash to be effective. Suppose I take a shot at f2.8, shuttle speed is 1/60. Should I then be checking to see if the flash can reach this distance (through looking at the flash table display on the flash) to make sure that fill is sufficient. How to I adjust the amount of flash output? Is that possible.
Second question is what would happen if I chose the shuttle speed to be over 1/80, say 1/125, what would happen. Also, when I use flash in this manner, do I have to adjust the shuttle speed mode to X. I suppose not, because by then, I will be lock into 1/80.
I hope someone can help me on this.
Many thanks

I think maybe you mean an F3HP? The F4 didn't have an "HP" version (well, all F4's were HP I guess). The F3 also has the 1/80 flash sync speed.

Sync speed of 1/80 means that's the fastest shutter speed you can use with flash. If you go faster (1/125, 1/250, etc) you'll only expose part of the frame, part will be blank. You won't hurt anything, try it if you want. You can use a longer exposure - like 1/60, 1/30 - as well, sometimes that can help keep the background from going too dark.

If you're using the flash totally manually, you would have to use the chart on the flash to determine which f-stop to use, or more for more accuracy use a flash meter. The two things that determine flash exposure are film speed (ISO) and aperture. Shutter speed will only affect the ambient light, so it sounds like you're looking for fill flash in fairly low light, judging by the F2.8 and 1/60 reading. I'm not sure about your particular flash, but it should have a sensor and a couple of auto modes (controlled by the flash and have nothing to do with the camera). You'll probably see two or three distance ranges that the subject can be from the flash based on the two things that affect flash exposure - which again are film speed and aperture.

Hope this helps.