confused on F stops and shutter speeds

[theartist53]

I'm confused. I know the F stop goes up when the shutter speed goes down but by how much? If I was at F8 for 1/60 what would be my new speed if I change to F16? Or if there's a big change from F22 at 1/500, what if I change to 1/125?

[FlyingPhotog]

To hold an equivalent exposure, each step up or down in aperture (f/stop) requires an equal but opposite change in shutter speed.

So however many stops you change your aperture, you need to change your shutter speed in the opposite direction by the same number.

[Jim G]

google the tedious explanation of the f-stop - it will explain all you need to know!

[tzalman]

See the sticky at the top of this forum "Ben's Newbie Guide"and all will be revealed.

[SkipD]

Originally Posted by theartist53

I'm confused. I know the F stop goes up when the shutter speed goes down but by how much? If I was at F8 for 1/60 what would be my new speed if I change to F16? Or if there's a big change from F22 at 1/500, what if I change to 1/125?

Why did you start a whole new thread with the same subject when you already had one going?

[TeeTee]

Please read http://www.uscoles.com/fstop.htm

Play with camera.

Again read http://www.uscoles.com/fstop.htm

Play again with camera.

[Hermeto]

Take a look at these sites:

http://www.photonhead.com/simcam/shutteraperture.php

http://web.canon.jp/imaging/enjoydslr/

http://www.usa.canon.com/content/reb...lxtlessons.htm

[Crossfire]

Also check out a book titled "Understanding Exposure" by Bryan Peterson

[gooble]

Originally Posted by theartist53

I'm confused. I know the F stop goes up when the shutter speed goes down but by how much? If I was at F8 for 1/60 what would be my new speed if I change to F16? Or if there's a big change from F22 at 1/500, what if I change to 1/125?

Learn what stops are. Basically, when you move up or down the f-stop scale or shutter speeds or ISO sensitivities 1 stop up or down will either double or halve exposure or EV.

So, the full f-stop scale looks like this: f/1, f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22 and so on. Moving up the scale, that is increasing the f-stop decreases EV.

Shutter speeds also follow this logic but it is a little easier to understand as you simply divide by two or multiply by 2 (in most cases). In seconds: 1, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000, 1/2000, 1/4000 etc. Also in this case, moving up the scale reduces EV by half with each step.

With ISO settings you typically have 100, 200, 400, 800, 1600, 3200, 6400, 12800 etc. Here though moving up the scale increases EV.

So, when one of these is adjusted, in order to maintain the same EV, per your question, one or both of the others must be adjusted to compensate. If you increase the EV with one you must decrease the EV with the others and vice versa.

So if you were set at f/8 with shutter of 1/60 and you wanted to move to f/16 you have to know the f-stop scale to know that you're decreasing the EV by two stops so you must increase the EV with the shutter speed by slowing it down, i.e. going from 1/60 to 1/15 sec. Or alternatively you could increase ISO sensitivity by moving from say, 100 to 400.