Maximum range for bounced flash?

Is there a way to get a rough estimate of the maximum range for effective bounced flash if you know ceiling height and flash guide number (for my speedlight the guide number is 50)? I understand that when we're dealing with bounced flash there are a lot of variables outside of our control, I'm just thinking in terms of being able to decide ahead of time whether a particular situation is totally impossible or that it might be workable.

thanks.

I don’t have a formula, but here’s what I normally do.

Set camera to manual and meter for ambient exposure starting at ISO 800. Take test shots until satisfied.

Set flash to the longest setting 105mm and ETTL. Take test shots and adjust camera setting until satisfied.

Watch the flash recycle rate. Normally I can hear the pop and whistle and know how hard the flash is working. Loud pop and long whistle mean the flash fired at full power. Now consider upping the ISO and maybe open up the lens (larger aperture) if possible.

More answers here on high ceiling bounce.

https://photography-on-the.net/forum/showthre​ad.php?t=451770

Too many variables to consider. ISO and reflectivity of the room for instance, and whether you need the bounce to be the primary light source or simply fill to kill shadows.

With a guide # of 50, I would be hesitant to work with a bounced flash in anything other than a normal size room (living room, kitchen, etc). If you are thinking of bouncing in a larger reception area with anything other than white walls, I would say you're going to tax your flash to its max.

jcolman wrote in post #15702989
With a guide # of 50, I would be hesitant to work with a bounced flash in anything other than a normal size room (living room, kitchen, etc). If you are thinking of bouncing in a larger reception area with anything other than white walls, I would say you're going to tax your flash to its max.

I should have been more specific, the guide number on my flash (Sigma EF-500 DG ST) is 50 meters/165 feet, so it has just a bit less power than a Canon 580 EX (58 m/190 ft).

groundloop wrote in post #15705671
I should have been more specific, the guide number on my flash (Sigma EF-500 DG ST) is 50 meters/165 feet, so it has just a bit less power than a Canon 580 EX (58 m/190 ft).

My comment is still valid. I have tried bouncing my 580EX at wedding receptions (back when I was just starting out) and grew quite frustrated trying to get the results I wanted. Long recycle times, lack of power, etc. I now shoot with multiple off camera lights at a reception.

I thought Curtis had a post about this. With todays high ISO cameras it shouldn't be that much of an issue. Why not test it yourself, it is easy.

BTW - For faster cycling always make sure you using external pack with the flash IMHO.

For a "normal" living room, if that now does exist, with white ceiling I'd say you loose about two stops when you bounce. So if you could use f/5.6 before, with the same power you have to go to f/2.8.
Or, if you got away with guide number 25, you need 50.

That's just a rule of thumb. You may loose three stops, depending on ceiling height, angles and such. Rarely less than two stops, unless there's a mirror in the ceiling...

Aren't these guide number at ISO100. I would assume indoors you typically ISO1600 or more at f2.8 or faster.

Here's a good example of "rule of thumb"

Bounce won't work.