Why f/8

[Plato]

We were all Canon thus the ISO...

Are you suggesting that Canon is the only manufacturer that offers ISO-100?

 

[LearnMyShot]

It was probably the sharpest point of the lens....but who would really notice? I think he wanted a 250th of a second to stop motion when shooting models..also it would throw the background out of focus...which is good even on a plain background to blend any unwanted shadows..

 

[NateWagner]

We were all Canon thus the ISO...

Are you suggesting that Canon is the only manufacturer that offers ISO-100?

He may have been, but it is true that many, if not most Nikon DSLR's are limited to 200 ISO at the low end.

 

[NateWagner]

I think he wanted a 250th of a second to stop motion when shooting models..also it would throw the background out of focus...which is good even on a plain background to blend any unwanted shadows..

Actually, I highly doubt he chose the 1/250 to stop the models motion. I mean typically 1/60 to 1/100 will do that unless they are running or something.

It (the 1/250) would really throw the background out of focus, that would be more of a result of the aperture and the subject/background distance from the camera.

 

[Dominantly]

Last weekend, I had my first experience in a studio sighting. All kinds of lights, including boxes, huge portraits, over head, and large ring lighting. It’s a whole new world of photography with models in a studio. But my question, this was a workshop and the instructor instructed us to set our cameras at 1/250 f/8 and ISO 100 for the shots as it would ensure everything was in focus and no bokeh affects. How did he know this? We were all Canon thus the ISO, but why f/8 when you have the best lighting available?
I've heard "just f/8", but why 8?

It's fairly common to see people shooting at large apertures, and placing the focal plane in the wrong spot. For example, someone shooting a portrait at f/1.8 and hitting a shoulder, or the tip of the nose, etc... when in fact they should be trying to get the eyes sharp and crisp.
When he told you to shoot at f/8, he was giving you more depth to your focal range. Now if you hit the nose, you will still get a sharp set of eyes.
Like mentioned, this is also where most lenses are the sharpest (f/8-f/11). So he was hooking you up two fold.

Also, the term Bokeh doesn't really fit here. Bokeh is the aesthetic quality of the out of focus objects.