Equivalent exposure: What is the method in which you use to arrive at the equivalent exposure? For example you want an equivalent exposure of f/8.0, 1/125, ISO 100 but you want to use...

BebuLamar

What is the method in which you use to arrive at the equivalent exposure? For example you want an equivalent exposure of f/8.0, 1/125, ISO 100 but you want to use different settings that gives the same exposure how would you go about to do that?

GalaxyCat Loc: Boston, MA

That's interesting. I'd like to learn that also.

Larryshuman

Raise one and lower the other.

Bill_de Loc: US

Wouldn't that depend on why you wanted to use different settings??

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GalaxyCat Loc: Boston, MA

Since Shutter speed is 1/125, is lowering it 1/250 or not?

Bill_de Loc: US

GalaxyCat wrote:

Since Shutter speed is 1/125, is lowering it 1/250 or not?

If you were given half the time to run a mile would you go faster or slower?

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Kozan Loc: Trenton Tennessee

BebuLamar wrote:

What is the method in which you use to arrive at the equivalent exposure? For example you want an equivalent exposure of f/8.0, 1/125, ISO 100 but you want to use different settings that gives the same exposure how would you go about to do that?

Changing the shutter speed by 2X or 1/2X changes by 1 f stop. So if you go from 1/125 s to 1/60s, you have increased the exposure by 1-stop. Therefore, you must either decrease the ISO by half or change f/8.0 to f/5.6 (1-stop).

A one stop change in F-stop is a factor of 1.4. (f/8.0 is 1.4 x 5.6). A 1-stop change in shutter speed is 2X or 1/2X the speed. Also, ISO changes by 2X or 1/2X.

Now that you are thoroughly confused, go watch a video.

RichardTaylor Loc: Sydney, Australia

BebuLamar wrote:

What is the method in which you use to arrive at the equivalent exposure? For example you want an equivalent exposure of f/8.0, 1/125, ISO 100 but you want to use different settings that gives the same exposure how would you go about to do that?

Do you understand the exposure triangle?

TriX Loc: Raleigh, NC

I think of it in terms of stops or EV.
Halving or doubling the shutter speed = + or - 1 stop in exposure change (respectively).
Doubling or halving the ISO = + or - 1 stop, and
Moving the aperture 1 fstop (f2.0 to 2.8, 2.8 to 4.0, etc) lower = +1 and higher = -1 stop.

So for example, if you double the ISO (+1 stop), you can either double the shutter speed (-1 stop), or raise the fstop -1 full stop for the equivalent exposure and vice versa.

ricardo7 Loc: Washington, DC - Santiago, Chile

Learn your STOPS:

f1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22 etc. Each change is 1 STOP

Shutter speed- 1, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000 etc. Each change is 1 STOP

ISO--100, 200, 400, 800, 1600, 3200, 6400 etc. Each change is 1 STOP

If you move one up, you have to move one down. If you move one down you have to move one up.

Digital cameras put everything is 1/3 stops, but if you know the fundamental numbers above, the rest all falls into place.

GalaxyCat Loc: Boston, MA

Wow! Wow! Wow! I gotta write this down! I understand changing shutter speed and/or size of the hole, but what does changing the ISO do in the digital camera?

ricardo7 wrote:

Learn your STOPS: br br f1.4, 2, 2.8, 4, 5.6, 8, ... (show quote)

BebuLamar

Bill_de wrote:

Wouldn't that depend on why you wanted to use different settings??

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Different settings because you may want a different DOF or a different type of motion blurr or a different ISO to get less or more noise.

BebuLamar

Kozan wrote:

Changing the shutter speed by 2X or 1/2X changes by 1 f stop. So if you go from 1/125 s to 1/60s, you have increased the exposure by 1-stop. Therefore, you must either decrease the ISO by half or change f/8.0 to f/5.6 (1-stop).

A one stop change in F-stop is a factor of 1.4. (f/8.0 is 1.4 x 5.6). A 1-stop change in shutter speed is 2X or 1/2X the speed. Also, ISO changes by 2X or 1/2X.

Now that you are thoroughly confused, go watch a video.

OK so it's counting the click!

BebuLamar

RichardTaylor wrote:

Do you understand the exposure triangle?

I am sorry! How do you use the triangle? With the example above but I wish to use f/2.8 instead of f/8.0. How do I use the triangle to figure out which shutter speed and /or ISO to get me the same exposure?

RichardTaylor Loc: Sydney, Australia

GalaxyCat wrote:

Wow! Wow! Wow! I gotta write this down! I understand changing shutter speed and/or size of the hole, but what does changing the ISO do in the digital camera?

It may allow you to select the shutter speed or aperture you want (depending on the light level and your camera). Increasing the ISO also increases the noise levels.