Someone Please Explain Fill flash

I understand what it is, what the pictures look like, but apparently, not how to make it happen. What settings to use on the camera and flash to get fill flash to work consistantly. I use the 30D, Bigma, 550ex and sometimes a Better Beamer attached to the flash.

What I would like to be able to do is use it for shooting small birds, generally within 18-25 feet from the camera in shaded woodlands conditions. Right now, I either get blown out images from too much flash, or I don't use it and rely on higher ISO and slower shutter speeds and try and fix the noise in CS2.

I see threads all the time that say to use fill flash, but nobody has explained how to do fill flash. Do I have to use Manual Mode or Av Mode, what settings for the camera, what settings on the flash? I've been testing different combinations for weeks now and I'm just getting more and more confused cause the outcome just doesn't seem to be consistant.

Any help would be great as I have a once in a year chance to shoot a rare and hard to find bird and would dearly love to get some top quality images of it in the next couple of weeks.

Fill flash requires that the camera evaluate the light from dozens of sensors to determine what your subject is before it can calculate the correct output (hence the term, Evaluative TTL metering). Now I haven't done a lot of bird flashing, but I imagine this can lead to inconsistencies if the bird is fairly small in the frame or surrounded by foliage. A black bird will certainly yield different results than a white bird. So it could be that there is no simple solution for the consistency problems you are experiencing.

Beyond that, this thread might be a good read.

Thanks Curtis. That link mentioned the metering modes. I'm going to play with that. Never entered my mind it would matter. Duhhh.....

Remember the metering mode on your camera (Evaluative, CW Average, Partial, Spot) affects ambient metering only.

The metering mode for flash (Evaluative or Average) is set with custom function 14 on the camera (custom function 8 for the RebelXT/XTI).

Thanks Curtis, I figured that out about an hour ago. Along with something else.

Can you believe I did not know that High Speed Sync was possible in Av Mode? Somehow, after the 30th read of the manuals for both my camera and flash, I was positive I had it down that setting the 1/250 Fixed for Av Mode custom function allowed you to use 1/250sec for flash. And that Auto, [now get this] Auto would let you use any speed UP TO 1/250sec. Does it say anywhere in the flash manual that setting it to Auto allows you to use High Speed Sync in Av Mode? No....

Anyway, I hope that help some other Mr. Stupid out there that just don't get it from reading those crappy Canon Manuals. Set the Sync in Av to Auto if you want to use HSS.

Anyway, it all works exactly as I thought it should but never got to work and I'm taking perfectly exposed fill flash pics now, directly into the sun. Me Happy...

canonloader wrote in post #3243821
Thanks Curtis, I figured that out about an hour ago. Along with something else.

Can you believe I did not know that High Speed Sync was possible in Av Mode? Somehow, after the 30th read of the manuals for both my camera and flash, I was positive I had it down that setting the 1/250 Fixed for Av Mode custom function allowed you to use 1/250sec for flash. And that Auto, [now get this] Auto would let you use any speed UP TO 1/250sec. Does it say anywhere in the flash manual that setting it to Auto allows you to use High Speed Sync in Av Mode? No....

Anyway, I hope that help some other Mr. Stupid out there that just don't get it from reading those crappy Canon Manuals. Set the Sync in Av to Auto if you want to use HSS.

Anyway, it all works exactly as I thought it should but never got to work and I'm taking perfectly exposed fill flash pics now, directly into the sun. Me Happy...

I had to figure that out by experimenting too. If it is too dark for HS flash (shutter speed 1/250 sec or less) then flash fill doesn't work very well. Flash has to be the more source of light. Then the flash will nail the bird down. If you try to use it as fill by decreasing the output, then the slow shutter speed will not stop movement.
If the light is bright allowing faster shutter speeds, then change the synch from 1/250 to auto synch and set the flash mode to HS (at least on the Sigma) then the multiple flashes provide the fill. Since the output is less, it has the same affect as lowering the FEC. At least this has been my experience.

Dennis, that's exactly what I wanted to do, I knew it should work that way, but I never connected the dots about 1/250 and Auto. Man, what a relief.

Mitch, I'm glad you're working through the frustrations and coming to grips with Canon's flash system.

FYI, the custom function that sets the shutter at flash sync speed in Av mode is intended for indoor flash when you want to eliminate the ambient and rely on flash alone for exposure. Using this function is really not Av mode at all, since the whole idea of Av mode is to allow the camera to set the shutter speed for proper ambient exposure. It's pretty much the same as using Manual mode and setting the shutter speed at 1/250 (which is the method I recommend - it's just easier).

I believe this custom function exists to mimic the behavior of other brands of cameras. Some of them are programmed to automatically use flash sync speed in Av mode if you turn the flash on. These cameras have a special "slow sync" function for using Av mode with fill flash.

As for high speed sync - It will reduce your maximum flash range, but it won't reduce the flash exposure by itself unless you're shooting beyond that range. Now there are legitimate reasons to use HSS. If you're using a long lens you may want a fast shutter speed to avoid camera shake. But simply dialing in some negative FEC is a more efficient and more predictable way to reduce flash output.

Thanks for hanging in there Curtis. I worked through FEC yesterday and got it to work using the settings on the camera and adjusting with the wheel. I can also set EV with the wheel for the camera compensation. The thing is, I understand all this and know what it should look like, but I was just missing that one piece to the puzzle. I'm surprised I got it right as many times as I did. I mean, I knew it wasn't right, just didn't know where the problem was. I thought it was the camera.

Curtis N wrote in post #3244969
Mitch, I'm glad you're working through the frustrations and coming to grips with Canon's flash system.

FYI, the custom function that sets the shutter at flash sync speed in Av mode is intended for indoor flash when you want to eliminate the ambient and rely on flash alone for exposure. Using this function is really not Av mode at all, since the whole idea of Av mode is to allow the camera to set the shutter speed for proper ambient exposure. It's pretty much the same as using Manual mode and setting the shutter speed at 1/250 (which is the method I recommend - it's just easier).

I believe this custom function exists to mimic the behavior of other brands of cameras. Some of them are programmed to automatically use flash sync speed in Av mode if you turn the flash on. These cameras have a special "slow sync" function for using Av mode with fill flash.

As for high speed sync - It will reduce your maximum flash range, but it won't reduce the flash exposure by itself unless you're shooting beyond that range. Now there are legitimate reasons to use HSS. If you're using a long lens you may want a fast shutter speed to avoid camera shake. But simply dialing in some negative FEC is a more efficient and more predictable way to reduce flash output.

So I should undo the custom function to lock the shutter at 1/250 in Av mode?
What about saftey shift, what exactly does it do?

Set custom function 3 to 0 (auto). This allows the camera to adjust the shutter speed to expose for ambient light. If you want to lock the shutter speed at 1/250, that's what Manual mode is for.

Custom function 16 (safety shift) should be set to 1 (enabled). Leave it there. All the time. Forever. This will save your butt on occasion.

For instance, suppose you're using fill flash outdoors in Av mode and forgot to turn on HSS. The camera will limit the shutter speed to 1/250, and if your aperture is too wide you'll get an overexposed shot from too much ambient. With safety shift, the camera will revert to Tv mode if it bumps against the 1/250 shutter speed limit. It will stop down the aperture for proper exposure and save the shot. Safety shift also works in Tv mode if you choose a shutter speed too fast and the lens can't get enough light when it's wide open. In this case it will slow down the shutter to avoid underexposure.

Curtis N wrote in post #3247550
Set custom function 3 to 0 (auto). This allows the camera to adjust the shutter speed to expose for ambient light. If you want to lock the shutter speed at 1/250, that's what Manual mode is for.

Custom function 16 (safety shift) should be set to 1 (enabled). Leave it there. All the time. Forever. This will save your butt on occasion.

For instance, suppose you're using fill flash outdoors in Av mode and forgot to turn on HSS. The camera will limit the shutter speed to 1/250, and if your aperture is too wide you'll get an overexposed shot from too much ambient. With safety shift, the camera will revert to Tv mode if it bumps against the 1/250 shutter speed limit. It will stop down the aperture for proper exposure and save the shot. Safety shift also works in Tv mode if you choose a shutter speed too fast and the lens can't get enough light when it's wide open. In this case it will slow down the shutter to avoid underexposure.

1 done

2 done

3 So with CFn 3 set to 0 (auto) indoors it will allow me shutter speeds faster than 1/250 for flash and outdoors it will not allow shutter speeds past 1/250?

I guess at the Chicago meet when you said Av, 200, f8 that was just a starting point, and not a place to live

I wonder if UPS would allow me to ship you a case of brew

Franko515 wrote in post #3247618
3 So with CFn 3 set to 0 (auto) indoors it will allow me shutter speeds faster than 1/250 for flash and outdoors it will not allow shutter speeds past 1/250?

1) Without HSS enabled, it will allow any shutter speed 1/250 or slower.
2) With HSS enabled, it will allow any shutter speed.
The camera will simply choose the shutter speed necessary for proper ambient exposure. That's what Av mode is for.

I guess at the Chicago meet when you said Av, 200, f8 that was just a starting point, and not a place to live

Actually it was Tv mode at 1/250 (go back and check the EXIF on those shots). It's a "no worries" approach for outdoor fill that maximizes the range of your flash by using the widest aperture and fastest shutter speed possible without going into HSS mode. It's not an artistically perfect setting for every scenario, but this approach will allow proper ambient and flash exposure for the widest range of focal lengths and distances when the sun is shining.

I'll take an IOU on the beer.

The key word here is ambient light. Just the light and it's the same thing you get if the flash wasn't on the camera. If it's only 1/60sec, then that's what it shoots at and flash "fills" in with enough light to expose the image properly, but the shutter still stays at 1/60sec. The HSS comes into play when the ambient light would set a shutter speed over 1/250sec, say 1/400sec. The flash will fire with enough light to correctly expose the image. Really good when ambient light is high, but your shooting a highly backlit subject. The fill will light the near side and not blow out the rest of the image.

Just highlighting that cause it was a little detail that it took me awhile to understand.

Curtis N wrote in post #3247793
1) Without HSS enabled, it will allow any shutter speed 1/250 or slower.
2) With HSS enabled, it will allow any shutter speed.
The camera will simply choose the shutter speed necessary for proper ambient exposure. That's what Av mode is for.Actually it was Tv mode at 1/250 (go back and check the EXIF on those shots). It's a "no worries" approach for outdoor fill that maximizes the range of your flash by using the widest aperture and fastest shutter speed possible without going into HSS mode. It's not an artistically perfect setting for every scenario, but this approach will allow proper ambient and flash exposure for the widest range of focal lengths and distances when the sun is shining.

I'll take an IOU on the beer.

My apologies sir, you are correct

canonloader wrote in post #3248058
The key word here is ambient light. Just the light and it's the same thing you get if the flash wasn't on the camera. If it's only 1/60sec, then that's what it shoots at and flash "fills" in with enough light to expose the image properly, but the shutter still stays at 1/60sec. The HSS comes into play when the ambient light would set a shutter speed over 1/250sec, say 1/400sec. The flash will fire with enough light to correctly expose the image. Really good when ambient light is high, but your shooting a highly backlit subject. The fill will light the near side and not blow out the rest of the image.

Just highlighting that cause it was a little detail that it took me awhile to understand.

Ok i feel really dumb
I thought C.Fn 3 was HSS but it only locks shutter speed to 1/250 and HSS is to be set on the flash not the camera. Even without C.Fn 3 the camera stops at 1/250 while using flash (in Av, Tv, and P) so whats the good of C.Fn ?

I now have C.Fn 3 set to 0
C.Fn 16 (saftey shift) set to enable
What about C.Fn 14 (ETTL II) eval. or average, and why?

I feel really lost with this flash I hate to not know how to do something , but I must admit I am totally lost. If you guys could speak in dummy terms Im sure I can catch on though

Thanks for all your patience