Something I never knew

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Michael Firstlight Veteran Member • Posts: 4,829
Something I never knew

Something I never knew...

I've been around the block a while, and if this is true I feel embarrassed, but I just listened to a lighting tutorial that said “flash output never varies” which actually makes sense after hearing the explanation.

Here’s how It was explained (paraphrasing):

Because most strobes allow us to vary the output “power” of the flash, we think the output of what we perceive being provided when capturing a flash image is greater or lesser depending on whether we set the flash to full or fractional. For example, setting the strobe to 1/2 or 1/32 doesn’t reduce the brightness of a single pop – it simply provides more (multiple) pops during the time the shutter is open. So, the effect is more or less light in aggregate, not more or less power of an individual flash actuation. In essence, then, the total output for a single image is in fact greater or lesser in aggregate due to more or fewer “mini-pops” while the camera shitter is open, but not from a single individual pop - those are always constant in output.  So, a 500W bulb is always putting out 500W - even when setting the power control to 1/64 vs full.

Is this accurate? It makes sense to me - as we reduce the power on the strobe the duration is shorter and shorter (which is how we can isolate and freeze the motion of a droplet of water) when creating a single image – we're just getting fewer pops while the shutter is open? Same with HSS – I already knew that HSS is just a high volume of fast multiple pops when exposing a single image while the shutter is open – but I never related that to (non-HSS) flash output in general. Duh!

I ask because my perception has always been the opposite. You know, you can even hear the difference when listening to the power of the strobe when you shoot – a loud pop sound at full power vs very little sound at fractional power. I now guess that’s just the sound of the capacitor unloading more pops during a single shutter open/close event.

True for all types of flash – speedlights and monolights?  I assume so. If so, I feel dumb thinking the opposite all this time – our “power level” controls are only the resulting perception and effect of flash in aggregate during a single image?


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The one thing everyone can agree on is that film photography has its negatives. It even has its positives and internegatives.

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