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Fill flash with long lenses and the Better Beamer
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<blockquote data-quote="WayneF" data-source="post: 610584" data-attributes="member: 12496"><p>I dont have, and have never used a Better Beamer. But the big problem with flash for birders is that a flash simply won't reach as far as a long lens will, for the bird in yonder far tree. A regular full powered flash at even 200 mm has a Guide Number of maybe GN 190 (feet). That means a bird at 60 feet needs 190/60 = f/3.1 (normal flash level, fill flash would need less light). The same picture view with a 300mm lens would be down about 1 stop at its greater distance, suitable for fill, except it still requires the f/3.1. But the 300 mm or 400 mm lens used for birding typically won't do f/3.1. You'd think higher ISO should help, but that increases the ambient light too, requiring stopping the lens down even more (since shutter speed ls limited by maximum sync requirements).</p><p></p><p>So the Better Beamer is just a fresnel lens that concentrates the spreading light from the flash into a tighter more concentrated beam, intensifying its light in that smaller area, to have a longer reach with a long lens. The only specs that their web site offers is "for lenses 300 mm and longer" and "increases light 2 2/3 f/stop". <a href="http://www.birdsasart.com/accs.html#BEAMER" target="_blank"> BIRDS AS ART.com</a></p><p></p><p>I would imagine any problem would be with accurately aiming it to be same as the lens aim. Guessing that pictures of the front of house from across the street in dim light should help to check the aim.</p></blockquote><p></p>
[QUOTE="WayneF, post: 610584, member: 12496"] I dont have, and have never used a Better Beamer. But the big problem with flash for birders is that a flash simply won't reach as far as a long lens will, for the bird in yonder far tree. A regular full powered flash at even 200 mm has a Guide Number of maybe GN 190 (feet). That means a bird at 60 feet needs 190/60 = f/3.1 (normal flash level, fill flash would need less light). The same picture view with a 300mm lens would be down about 1 stop at its greater distance, suitable for fill, except it still requires the f/3.1. But the 300 mm or 400 mm lens used for birding typically won't do f/3.1. You'd think higher ISO should help, but that increases the ambient light too, requiring stopping the lens down even more (since shutter speed ls limited by maximum sync requirements). So the Better Beamer is just a fresnel lens that concentrates the spreading light from the flash into a tighter more concentrated beam, intensifying its light in that smaller area, to have a longer reach with a long lens. The only specs that their web site offers is "for lenses 300 mm and longer" and "increases light 2 2/3 f/stop". [URL="http://www.birdsasart.com/accs.html#BEAMER"] BIRDS AS ART.com[/URL] I would imagine any problem would be with accurately aiming it to be same as the lens aim. Guessing that pictures of the front of house from across the street in dim light should help to check the aim. [/QUOTE]
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Fill flash with long lenses and the Better Beamer
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