Flashgun quick question...

Robbo

Robbo

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....call me stupid but.....on the zoom on my flash ranging from 25-85mm (i think)
....does it increase and decrease power slightly or is this for the spread of the flash?

If its the spread which is widest?

thanks
 
As steve said.. the more you zoom in the narrow the spread of light...

This normally only works with the head at 90 deg to the body, pointing forward..


:thumbs:
 
markw08 said:
As steve said.. the more you zoom in the narrow the spread of light...

This normally only works with the head at 90 deg to the body, pointing forward..


:thumbs:
Click to expand...

That's maybe the answer Robbo was after, but it's not the full story.

The intensity of the flash reduces as the angle of coverage is increased, because the light is spread over a larger area. Hence why the Guide Number is always quoted at the longest focal length setting as that produces the highest figure.

It falls off broadly in line with the inverse square law, as it must do, but in practice it's not quite that severe with my Canon guns - I only lose about a stop from 105mm down to 24mm.
 
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