flashes with canon 50mm 1.8

[richboyphoto]

so today it was pretty sunny out, we shot some photos and my flashes seemed to of been barely lighting anything up, at one point i had 3 all at full power, and you couldnt even tell flashes were being used.

i put on my fisheye and it was absolutely fine, all three completley over-exposed the shot on the same f stop my 50mm was at. completley baffled, anyone know what this could be?

 

[s.coller]

im not sure about the fisheye lenses but i do know that the f number doesn't coraspond to the acual size of the aperture. its the focal length devided by the f number so f1.8 at 50mm is smaller than f1.8 at 100mm.
I'm no expert but maybe thats why your getting an inconsistent amount of light even though the f number is the same.

 

[hairboy]

im not sure about the fisheye lenses but i do know that the f number doesn't coraspond to the acual size of the aperture. its the focal length devided by the f number so f1.8 at 50mm is smaller than f1.8 at 100mm.
I'm no expert but maybe thats why your getting an inconsistent amount of light even though the f number is the same.

Sorry, but you are mistaken there. F number is the unit of aperture, and it is exactly the same, regardless of focal length.

To OP, first, put the camera and flash into M. Stick your shutter speed at 160th second (which I believe is the max sync speed on your Canon). ISO at lowest. Take a shot without flash. Then dial your aperture to get the background looking good. Then turn on 1 of the flash at the position you want. Take a shot. Adjust power to suit.

Job done

Edit to add: missed the first bit that said it was a sunny day. it could well have been that your flashes aren't powerful enough. On a sunny day, your aperture will follow Sunny 16 theory. To get that, you will need a lot of power. The chances were 1 flash just didn't do enough.

You have a few choices:
1) if you have more than one, stick all of them in the same position. 2= double power (1 stop more light), 3 = 2.5 times brigher (1.5 stops more light).
2) get the light closer to subject - inverse square law
3) take the subject into shade, and avoid direct sunlit area.

Hope that helps.

 

[richboyphoto]

Sorry, but you are mistaken there. F number is the unit of aperture, and it is exactly the same, regardless of focal length.

To OP, first, put the camera and flash into M. Stick your shutter speed at 160th second (which I believe is the max sync speed on your Canon). ISO at lowest. Take a shot without flash. Then dial your aperture to get the background looking good. Then turn on 1 of the flash at the position you want. Take a shot. Adjust power to suit.

Job done

Edit to add: missed the first bit that said it was a sunny day. it could well have been that your flashes aren't powerful enough. On a sunny day, your aperture will follow Sunny 16 theory. To get that, you will need a lot of power. The chances were 1 flash just didn't do enough.

You have a few choices:
1) if you have more than one, stick all of them in the same position. 2= double power (1 stop more light), 3 = 2.5 times brigher (1.5 stops more light).
2) get the light closer to subject - inverse square law
3) take the subject into shade, and avoid direct sunlit area.

Hope that helps.

Thanks for the reply, my point is the exact same lighting setup was effective with my fisheye but not on the 50mm (both with the exact same settings, my canon syncs at 1/250) so i didn't understand what was going on. my flashes are powerful enough as they coped fine with the fisheye shots.

 

[Michael Sewell]

Is it possible you were much closer to your subject with the fisheye, as too, were your speedlights.
If that is the case, your speedlights won't have to work as hard to illuminate the subject when much closer.
The Inverse Square Law plays a major part here