Flash stopping power
/forum/topic/1167187/0



misteral
Registered: Aug 24, 2012
Total Posts: 2
Country: Canada

Hello!

Please bear with my question... In This Photo, Mr Strobist himself says "300/2.8 will stop at 1/250th better than a 400/2.8"

My question then, how does this sort of thing apply to our normal exposure triangle? All things being equal, I move the aperture up and shutter speed down and I've compensated 1 stop with another. (yes I'm being overly simplistic here, I am more referring to the light levels than how the final photo will look).

What needs to be considered then when adding in a flash? Add in a flash that syncs at 1/250 and then what? Is there a way to add in the flash to the equation? Any resources you can recomend?

Thanks!



Mishu01
Registered: Nov 20, 2009
Total Posts: 2325
Country: Romania

Well... English is not my first language but IMHO the quote is not about exposure... 1/250 is the sync speed so the camera will record more motion blur from a longer lens than from a shorter one... ideally you need to shoot at least at 1/focal length seconds in order to avoid motion blur... When the sync speed is 1/250 is obviously that the shorter lens acts better...

Don't take my words as Scripture... English plays with me sometimes



misteral
Registered: Aug 24, 2012
Total Posts: 2
Country: Canada

Your English is better than my Romanian


If I'm understanding you, and again I'm using the most basic concept on this...

Sync is 1/250, so at 300mm you would "ideally" use a shutter speed of 1/300, and at 400mm of 1/400, so in THIS case 300 being closer to 250.

I think I'm getting it..

mulțumesc!



Mishu01
Registered: Nov 20, 2009
Total Posts: 2325
Country: Romania

Correct! That's why he counts five compromises... not just the usual three from the exposure triangle. Bringing a flash in the equation when shooting with long lenses is tricky. (well, for me flash is always tricky )

Glad to help someone who know to properly spell "mulțumesc"!



Steve Wylie
Registered: Feb 13, 2007
Total Posts: 1098
Country: United States

It's simply that motion blur will show up more with a longer lens than with a wider lens. More pixels are devoted to the blurry area in a close-up photo than in a wider one. That's why wide-angle landscape shots appear to be sharper than closeups. The flash does not change the "stopping power" from one lens to another.



no_surrender
Registered: Apr 23, 2011
Total Posts: 1128
Country: Italy

Steve, I've been meaning to ask you...do you use flash during your night game photography? My squadron football team has been asking me to shoot a game for them, but I know nothing about how you do what you do.

I finally got some strobes and was thinking long throw reflector, but don't want to be blinding or distracting the players during the game. With that being said, I turned down the shoot altogether.

Kevin