This is a crazy conversation. Of course there is a difference.
It\'s the same as selecting the right nozzle for a spray gun or a brush size and shape in Photoshop.
Can you approximate one tool for another? In many ways yes, but clearly the SB (rectangular or square) offers greater edge control than the octa.
The SB\'s inherently conform to the photographic FOV more precisely and are usually the most effective tool to use when the greatest modifier size and coverage is desired but extraneous light is not. Having said that though, it is often easier to build octa with greater surface area that can still be self supporting than a square/recta because of the difference in the number of supporting rods.
Octas also attenuate light more gradually when feathering. This can be a plus or a minus, but is certainly a clear difference between these shapes.
(While feathering is a fundamental lighting technique, I\'m really beginning to wonder if it is becoming anachronism. )
Some octas can be configured more parabolic to focus light, say like a Para, a briese or even the Deep Octa.
Octas generally offer a more omnidirectional light quality, which can be desirable but that also requires more control.
Gridding is not always the best solution for control as that will substantially affect that omnidirectional quality of the light. Flags and gobos are other tools besides grids that can be effectively employed to manage spill (as Joe is doing with the reflector above) with either SB or octa, but the octa will often benefit more dramatically by introduction of an edge that did not already exist. I often use my Deep Octa with the internal diffuser to make use of the outer edge of the box as a \"lens shade\" for a nice soft light in a lower key situation..
The DO is a very unique modifier and will probably produce the closest look you are describing right out of the box.
But Shoe you need to get a handle on what Chuck, Simon, C.D. and others are trying to help you understand, which is that the best solutions don\'t usually come prepackaged in a box.
You can\'t have the perfect club for every situation out on the links, but even if you could you\'d still need to know how to use them if it\'s going to make a difference.
Like we say on the golf course.... pick a club and hit the dang ball or we\'re playing through.
Fore.
Dec 08, 2008 at 12:20 AM
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