Better Beamer/580EX range?

Yesterday I put my Better Beamer on my 580EX flash and went to a beach to try to get some gull shots. No gulls--they were all down by the lake (Michigan) on the other side of the river where the dozer was pushing sand back to the beach. I set the flash on 50mm manual zoom as recommended, and put the BB on the camera (20D) with ISO set to 200. Lens was Sigma 70-200 f2.8 with a 1.4x t-con. The flash said the range was only about 25 feet! FEC -2/3 ETTL, no EC on camera. It has to be better than this doesn't it? There was a closed Ice Cream stand about 100+ feet away. I pointed and shot it. When I got home and looked at that photo--I could see inside the store though the glass--there was even some stuff on the wall I could see. When I took the photo, I could not see inside though the window TTL and I did not have a CP on the lens. I then went over and took some shots with my WA at the dozer--didn't want to get sand in my shoes so no gulls.

What sort of range can I expect with this Better Beamer to get a twinkle in a bird's eye! I figure with crop factor and the TC, I'm over the 300mm zoom range recommended by BB, and many birds are higher than 20'.

I can't imagine the flash knows that the better beamer is attached. It's giving you the range without the BB.

Figure twice what the range says on the back of the flash. Unless your using it for fill flash. Then you might get a little more. But, you can always shoot in RAW and save even more in the RAW editor.

Flash guide number on 580 is 190.

BB gives you 2 stops or so. So to find range you divide aperture into guide number.

If you're shooting f/4 with no BB then 190/4=47.5 feet for FULL flash coverage of subject.

BB would make f/4 into f/2 so 190/2=80 feet

OK--thanks. It looks like I could roughly safely guess at about tx what is displayed on the screen? Isn't the 190 G# for the full flash zoomed to 105? I don't have my manual handy. I guess I need more practice with this gizmo! Seems to make a difference though!

A guide number tells you the relative power of the flash it doesn't mean it will reach 190 feet at 105mm. A guide number is also rated for ISO 100. If you double the ISO speed the distance doesn't double but increases by a rate of 1.4X as compared in the above examples. Guide numbers are also optimistic and I don't have any exact measurement on how many stops you gain with the BB so it is a educated guess on the 2 stops for the BB

That's why they put that little monitor on the back of the camera.

morehtml wrote in post #3179105
BB would make f/4 into f/2 so 190/2=80 feet

190/2 is not 80...it's 95.

I think you may be using too much light. Most photographers I know, (including myself) shoot the Better Beamer at - 1 2/3 stops not - 2/3 stops. Of course this depends on a lot of factors. However to give you some idea, I shoot at - 1 2/3 stops 90 % of the time, perhaps more.

I use the BB primarily for adding seperation to birds plummage and adding catchlight to the eyes. If you're shooting in the shade, or on a coudy day the BB can make the difference of getting an acceptable shot or not.