F and S

[cthomas]

:confused: Are these combinations of shutter speed and aperture always the same?


1/2000, 1/1000, 1/500, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8, 1/4

1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32


Would you ever choose 1/125 and f-8 or 1/125 and f-4, or would it always be 1/125 and f-5.6? file:///C:/DOCUME%7E1/CTHOMA%7E1.STL/LOCALS%7E1/Temp/moz-screenshot.jpgfile:///C:/DOCUME%7E1/CTHOMA%7E1.STL/LOCALS%7E1/Temp/moz-screenshot-1.jpg

[Heatseeker99]

yes sir.

[ofdphoto]

Hi,

For starters, I can't see any images because you didn't upload them ... you just linked to them on your hard drive.

Anyway, this question should probably be in one of the 'knowhow' forums, but I'll have a go at answering it here.

The appropriate combination of shutter speed and aperture will depend on your film speed (ISO) and the amount of light in the scene you're taking a picture of. For example, in bright light, 1/2000 and f/5.6 might be a correct setting, while inside, 1/30 and f/5.6 might be correct (in the latter case you need to let more light in for a correct exposure, hence the longer shutter speed).

Film/sensor speed further complicates things because it represents sensitivitiy to light. With ISO 100, you might have f/5.6 and 1/500 as a correct exposure; then increase the sensitivity to ISO 400, and you'll need f/2.8 (wider aperture) or 1/125 (slow shutter) to compensate.

This stuff is explained really well in Bryan Peterson's book Understanding Exposure. You should read it or something similar :-)

[ofdphoto]

Sorry, maybe I got your question wrong ... if you're saying, are these numbers always the same, then, yes ... the numbers you've listed are '1 stop' apart from each other and are always the same. But just to confuse you, you can have half- or third- stops in-between the numbers you've listed ;-)

[Bosman]

Those are true in relationship to each other for the same scene and same camera settings. A shutter speed and aperture are not linked to each other. They have a relationship to other apertures and shutter speeds when metering a scene with the same camera settings. If you a shot requires 1/250 at f2.8 at ISO 100, the same shot would be 1/125 at f4.0 at ISO 100.

[cthomas]

Those are true in relationship to each other for the same scene and same camera settings. A shutter speed and aperture are not linked to each other. They have a relationship to other apertures and shutter speeds when metering a scene with the same camera settings. If you a shot requires 1/250 at f2.8 at ISO 100, the same shot would be 1/125 at f4.0 at ISO 100.

I think relationship between shutter speed and aperture is the hardest stuff I have ever tried to learn (even learning Greek wasn't this hard). I know people tell me I have a hard thick head.:)

Reading Bryan Peterson's book Understanding Exposure and other books have help. These fourms have helped a lot because different people explan it differently so that helps.

[cc10d]

"Film/sensor speed further complicates things because it represents sensitivitiy to light. With ISO 100, you might have f/5.6 and 1/500 as a correct exposure; then increase the sensitivity to ISO 400, and you'll need f/2.8 (wider aperture) or 1/125 (slow shutter) to compensate"

FWIW

I think that this example was inadvertently reversed.... Higher ISO settings require less light not more. Thus the f5.6 and 1/500 sec. and ISO 100 under the same lighting would convert to f5.6 @ 1/2000 sec. at ISO 400. Or f11 @1/500 sec. and ISO400.

[ofdphoto]

"Film/sensor speed further complicates things because it represents sensitivitiy to light. With ISO 100, you might have f/5.6 and 1/500 as a correct exposure; then increase the sensitivity to ISO 400, and you'll need f/2.8 (wider aperture) or 1/125 (slow shutter) to compensate"

FWIW

I think that this example was inadvertently reversed.... Higher ISO settings require less light not more. Thus the f5.6 and 1/500 sec. and ISO 100 under the same lighting would convert to f5.6 @ 1/2000 sec. at ISO 400. Or f11 @1/500 sec. and ISO400.

Ahhh yes ... woops. Thanks!!

[cthomas]

So to determine what shutter speed, aperture and ISO to use. I would look at the scene and ask my self some questions like: What DOF do I want? What kind of lighting is falling on he scene? Is there movement? If so . To what extent do I want to show movement? What is the lowest ISO I can use to achieve the anwsers to these questions so that I will have the least noise. I know that there are some other things that may come in to play but are these the basics?

Half or Full? When you make the aperture smaller you get a half stop and when you make it bigger you get a full stop? When you make the aperture smaller the shutter speed gets slower and you get a half stop. And when you make the aperture bigger the shutter speed gets faster and you get a full stop? :confused::confused:

[angryhampster]

Read up on this:

http://www.apogeephoto.com/feb2003/Mkees2_2003.shtml


That *should* help!

[cc10d]

Yes those are things to consider when setting up for your shot.

Each step that you listed above is a full stop worth of light, regardless of whether it is shutter step or arperture step. If you move the shutter to a lower number, ei from 1/125 to 1/250, it is one stop less light value. Now this may seem like a bigger number but it is not, it is a fraction of a second. So the higher the numeric on the bottom of the fraction, the smaller its value is. So then 1/125 is more time the shutter is open than is 1/250. So the longer the shutter is open the more light gets in.

Now then the aperture steps work this way. The smaller the number, the MORE light gets in. f2.8 let in more light than f4.0 for a given shutter speed. So more depth of field also is less light for a given shutter speed, so we compensate by slowing the shutter speed by the same number of stops value as we closed down the aperture...

OK? well then since each step you list above is a full stop of light value, if you move the combination from say 1/125 @ f 8.0 to 1/250 @ f5.6, you have the same light value getting to the sensor. This example moved the shutter l stop less light and opened the aperature 1 stop more light, to give us the same light value as the first combination was. Hope that is helpful...

[cc10d]

angryhampster

Very good link, You posted that while I was typing and proofing my stuff. I did not see it till after I posted.

[JNunn]

:confused: Are these combinations of shutter speed and aperture always the same?


1/2000, 1/1000, 1/500, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8, 1/4

1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32


Would you ever choose 1/125 and f-8 or 1/125 and f-4, or would it always be 1/125 and f-5.6? file:///C:/DOCUME%7E1/CTHOMA%7E1.STL/LOCALS%7E1/Temp/moz-screenshot.jpgfile:///C:/DOCUME%7E1/CTHOMA%7E1.STL/LOCALS%7E1/Temp/moz-screenshot-1.jpg

The relationships are alot easier to see on a manual, internal shutter lens (as in Carl Zeiss, Schneider, Mamiya, etc. Medium format, for example) where you set the EV (exposure value) according to readings from your hand held light meter, by rotaing the appropriate ring on the lens. Then depending upon the DOF you want, you grab both rings (shutter speed and aperture) at the same time and rotate them achieving a different shutter speed/aperture combination. Both move at the same time which demonstrates the relationship they have to one another.

Its not a mystery at all when its done manually. Check out a Hasselblad at your local camera store and see what I mean. You can see each combination right on the lens.