What constitutes a 'stop'?

[terry.langham]

Been looking for a quick reference chart to work out the difference in highlight and shadow EV's to make selecting GND's a bit easier. Haven't had much luck, so thought I would have a go at knocking one up myself. Looking at the Jiffy (http://www.stacken.kth.se/~maxz/files/jiffy.pdf) calculator, are the aperture and shutter speed listed in 1/3 or 1/2 stop increments?

Cheers

[Xenedis]

Those are listed in third stops (and half-stops where appropriate).

For your convenience, here's a quick list of f/stops from f/1 to f/16, with the incremental distance noted.


f/1 (full-stop)
f/1.2 (half-stop)
f/1.4 (full-stop)
f/1.6 (third-stop)
f/1.8 (third-stop)
f/2 (full-stop)
f/2.2 (third-stop)
f/2.5 (third-stop)
f/2.8 (full-stop)
f/3.2 (third-stop)
f/3.5 (third-stop)
f/4 (full-stop)
f/4.5 (third-stop)
f/5 (third-stop)
f/5.6 (full-stop)
f/6.3 (third-stop)
f/7.1 (third-stop)
f/8 (full-stop)
f/9 (third-stop)
f/10 (third-stop)
f/11 (full-stop)
f/13 (third-stop)
f/14 (third-stop)
f/11 (full-stop)


HTH.

PS: Note that f/1.2 is the only half-stop in that range.

[etherial]

A stop put simply is the doubling or halving of light. ie f4 to f5.6 is one stop, 1/100 to 1/200 is one stop, ISO400 to ISO800 is one stop.

[Kym]

NTP has it all...

http://www.ausphotography.net.au/forum/showthread.php?t=24079

http://www.ausphotography.net.au/forum/showthread.php?t=33981

[ameerat42]

What constitutes a 'stop'?

Well, Terry, taking your question more generally, a cessation of motion relative to an observer should fit the bill.

But back to photography, I once had an old camera (an Agfa I think) that had a continuous aperture adjustment. It had "STOP" signs marked, like f/4, f/5.6, but stopping at them was optional, and at best approximate, rather more like "Give Way" signs.:umm: