An Incredily Newbie Type Question

PhotoJunkieJen · Feb 10, 2009

So I'm actually a bit asahmed I have to ask this... but here goes.

I understand about aperture and shutter speed. I understand, the faster the shutter, the lower the aperture and vice verse. I understand how to shoot on manuel and such.

But what I don't understand is what someone means when they say to up or lower the exposure by a stop.. or 2/3 of a stop.

Like, I understand that means "Change the Aperture." But how much exactly is a "stop"?

Big Mike · Feb 10, 2009

A stop is a full halving or doubleing of the amount of light. So if you open then aperture enough to double the area, it's one full stop. From F8 to F5.6 (or F8 to F11) for example. You could also change the shutter speed by a stop by going from 1/30 to 1/60 (or 1/30 to 1/15).
One stop is also 2X or 1/2 in ISO. 100 to 200 etc.

To give us more precise adjustment, many cameras can now be adjusted to steps between full stops...that's where you get halves or thirds of a stop.

tsaraleksi · Feb 10, 2009

1.0, 1.4, 2.0, 2.8, 4.0, 5.6, 8, 11, 16, 22. I believe those are the full stop that are of interest to 35mm photographers, but I can't ever remember the exact spaces between 1 and 1.4.

Mongoos3 · Feb 10, 2009

Manuel Settings??? I'm pretty sure your DSLR wasn't made in Mexico.

wes · Feb 10, 2009

PhotoJunkieJen said:
But what I don't understand is what someone means when they say to up or lower the exposure by a stop.. or 2/3 of a stop?

When you look in your viewfinder there is a scale with 0 in the middle and then +/- settings to the left or right of 0. When someone says to adjust your exposure they are most likely refering to adjusting you exposure comp up or down to either under expose or over expose. I think that is what your are getting at.

rufus5150 · Feb 10, 2009

tsaraleksi said:
... but I can't ever remember the exact spaces between 1 and 1.4.

1.0, 1.1, 1.2, 1.4 for 1/3rd stops, 1.0, 1.2, 1.4 for half stops. I think there's some rounding going on when you get down that far

bigtwinky · Feb 10, 2009

You ensure a proper photographic exposure by using a mix of aperture, shutter speed and ISO. Each is changed depending on light and your artistic intent.

When someone says to adjust the exposure, I would think they mean that you purposely over or under expose your picture, again, for artistic intent.

You have a scale that typically goes from

–2…-1…0…1…2

When you meter a scene, you should be adjusting your aperture, shutter and ISO so your arrow is aligned with the 0 on the scale. If you want to under expose by 1/3 of a stop, but keep the same aperture / shutter / iso, you can move the arrow to the left of the 0, which would be between the –1 and the 0, closer to the 0.

AlexColeman · Feb 10, 2009

They have all told you, just letting in one more or less stop of light.

TJ K · Feb 10, 2009

Mongoos3 said:
Manuel Settings??? I'm pretty sure your DSLR wasn't made in Mexico.

I got a good laugh out of this.

PhotoJunkieJen · Feb 11, 2009

TJ K said:
I got a good laugh out of this.

Me too, that was pretty good. :lmao:

PhotoJunkieJen · Feb 11, 2009

Big Mike said:
A stop is a full halving or doubleing of the amount of light. So if you open then aperture enough to double the area, it's one full stop. From F8 to F5.6 (or F8 to F11) for example. You could also change the shutter speed by a stop by going from 1/30 to 1/60 (or 1/30 to 1/15).
One stop is also 2X or 1/2 in ISO. 100 to 200 etc.

To give us more precise adjustment, many cameras can now be adjusted to steps between full stops...that's where you get halves or thirds of a stop.

So I see the logic in halving the shutter, ie: 1/120 to 1/60. And halving the ISO... from say 400 to 200.

But the aperture? The math doesn't make sense? Is that just something I have to memorize?

tsaraleksi · Feb 11, 2009

PhotoJunkieJen said:
So I see the logic in halving the shutter, ie: 1/120 to 1/60. And halving the ISO... from say 400 to 200.

But the aperture? The math doesn't make sense? Is that just something I have to memorize?

They're ratios. 1:1.4 1:5.6 or whatever. They just are what they are, memorizing them isn't hard if you shoot a lot.

Big Mike · Feb 11, 2009

But the aperture? The math doesn't make sense? Is that just something I have to memorize?

It's not numerically linear, so yes, it can be confusing at first. Most people do remember them after seeing and using them for a while. F2.8, F4, F5.6, F8, F11, F16 etc...it's not that hard to remember.

If it helps you, each full stop can be calculated by multiplying the F number by the square root of 2.

Really, the important part is that you know that higher numbers mean a smaller aperture and lower numbers mean a larger aperture.

Beth81 · Feb 11, 2009

PhotoJunkieJen said:
So I'm actually a bit asahmed I have to ask this...

Don't be ashamed to ask any questions if you don't understand. TRUST ME..I have asked all kinds of dumb questions but how else will you learn? Not everyone can understand things just from reading books....I know I didn't.

PhotoJunkieJen · Feb 11, 2009

Beth81 said:
Don't be ashamed to ask any questions if you don't understand. TRUST ME..I have asked all kinds of dumb questions but how else will you learn? Not everyone can understand things just from reading books....I know I didn't.

The adage "The more I know, the more I find I have to learn" comes to mind for me. :lol:

Man, there are days I think I'm making progress... then there are others I see how far I have to go. I guess it's the chase that keeps things interesting though.