photographic triangle ?

[doublehmom]

Okay, I hope I can make myself clear because I don't really know what I am talking about~still learning. Is there a cheat-sheet chart that tells you what aperture to use if you have a 1/60 shutter speed or vice versus? I have seen somewhere a chart that has shutter speed on the left, aperture on the right, and ISO at the bottom and to get a perfect exposure, one needs to make sure it fits in a triangle. Is this right or am I totally off base?

[egordon99]

Bryan Peterson's "Understanding Exposure" covers this as well as many other basic concepts of photography.
-Shutter speeds are doubled/halved every "stop"
-ISO just goes 100, 200, 400, 800, 1600, 3200, 6400 (just doubles)
-f-stops go 1, 1.4, 2, 2.8, 4, 5.6, 8, 11,....

So if you're at f/2.8, ISO100, 1/500s and want to keep the "exposure" the same, you could increase the f-stop to f/2, and then bump the shutter speed up to 1/1000s.

It's really not that difficult and shouldn't require a "chart"

The shutter speeds/ISOs can be done in your head as it's just multiplying/dividing by 2. f-stops is doubling every OTHER f-stop, and multiplying by the square root of 2 for each stop. Clear as mud, eh?

:)

[rammy]

I have seen somewhere a chart that has shutter speed on the left, aperture on the right, and ISO at the bottom and to get a perfect exposure, one needs to make sure it fits in a triangle. Is this right or am I totally off base?

For what type of scene?

Imagine this, if you were to take a correctly exposed shot at say F/16, 1/125 at ISO 100 in daytime and then did the same indoors, do you think the one indoors will be under (darker) or over (lighter) exposed?

The chart that you are looking at may have been some type of the sunny 16 rule for different aperture, ISO, shutter speed combinations. Or some other type of specific situation.

So you have to first adjust your three settings (aperture, ISO, shutterspeed) for the light in your given scene. Then, for example, if you wanted to change the aperture (for DOF or available light reasons) or the shutterspeed (for fast/slow moving objects or available light reasons) or ISO (for amount of available light or flash guide settings) then changing one of those settings "1 stop" either way would mean you would have to change one other setting the opposite direction 1 stop for the same exposure.

[Bumgardnern]

I think you are talking about an exposure wheel.

Here is an example of one. Not the best example I have ever seen though...

http://training.sessions.edu/design-tools/photography-exposure-wheel.asp

The idea of the exposure wheel is that if you know the proper exposure but say you want to change your aperture from f 16 to f1.4 that you don't have to do the math but can instead use the chart as a quick reference to know how many stops down that is and find the new shutter speed that corresponds with it.

[20droger]

Or you can use my Exposure Slide Rule. PM me your email address for the plans.

[doublehmom]

You guys are awesome. This helps me out immensely.

[Mark_Cohran]

There is no one perfect setting for a given ISO, aperture or shutter speed. It depends entirely on what it is that you want to capture in your image. The posters above are providing you with information that can help you determine the relationship between exposure, shutter speed and ISO for a given set of lighting (exposure) conditions, but you have to decide if you want a shallow depth of field, if you need a fast shutter speed to stop action or a slow shutter speed to accentuate motion, or a low ISO to minimize noise. Even with the charts, wheels and slide rules it comes down to a matter of choices and compromises.

[gooble]

I think you are talking about an exposure wheel.

Here is an example of one. Not the best example I have ever seen though...

http://training.sessions.edu/design-tools/photography-exposure-wheel.asp

The idea of the exposure wheel is that if you know the proper exposure but say you want to change your aperture from f 16 to f1.4 that you don't have to do the math but can instead use the chart as a quick reference to know how many stops down that is and find the new shutter speed that corresponds with it.

What math? It doesn't have to involve any math other than being able to count.

[20droger]

What math? It doesn't have to involve any math other than being able to count.
Well, judging by various reality shows on TV, quite a few people can't count, say the alphabet, stand on one leg, walk a straight line, etc.

[JeffreyG]

Before any ISO / aperture / shutter speed chart can work, you also need to know how much light is actually falling on the subject too.

This little device measures the light (A) which you manually transfer to the dial (B). Set the ISO (C) and every possible aperture and shutter speed combination can be read off (D). In this case the selected ISO3200 would yield a correct exposure at f/4 and 1/250 for example.