So.. for indoors flash in a ‘normal’ environment (i.e. a room with not too much, not too little light), here is my new, “restated-as-an-easier-mnemonic” rule of thumb:
The 400-40-4 rule (a.k.a. the “4-4-4-rule”).
As a simple starting point, do the following:
- Flash aimed 45 degrees up, behind you
- 400 ISO
- 1/40th second
That will give you an ambient light exposure of around -2 stops. Which looks like this:
Of course if your background is now too dark, you can raise ISO, lower f-number, or slow down shutter. If on the other hand the background is too bright, lower the ISO, select a faster shutter speed, or increase the f-number.
Often, simple rules of thumb are the secret to success. And simplicity is key – “4-4-4” sounds simple enough to remember, no?