Stops

[Kerbouchard]

Just to try and help you understand more, when you are in your semi-auto modes ( like Av and Tv mode on Canon, and uhhh I think S and A?? modes on Nikon??? ) if you are in lets say Shutter Priority, if you adjust the exposure comp for an underexposure, the camera will stop down the lens because it knows you want the shutter speed to be what you chose. If in Aperture priority mode, it will speed up the shutter. Both would be done by "Underexposing" on the exposure comp wheel, but would be achieved by different settings.

I shoot 100% manual. So to stop down an exposure, would I need to underexpose all three? (ISO, Shutter, Aperture)

Since I think it was me who said to underexpose ambient by about a stop and let the flash pull the subject up to the proper exposure level, I figured I would chime in, even though you have already gotten some excellent answers.

Since I was talking about using flash, it kind of changes the answers, but not all that much. If I have a powerful enough flash, I will pretty much always shoot at base ISO(the lowest native ISO the camera has available), so I will discard that one for now. Now, we have aperture and shutter speed left. Since aperture effects flash power and ambient, it's not the best thing to use as a control. So, my preference for underexposing the background or ambient lighting would be to use shutter speed. Now, if I can't increase my shutter speed because of flash sync(basically a limit where your shutter speed is so fast that one part of the shutter is closing before the other is fully open, therefore the flash exposure doesn't reach the entire sensor causing a black line across the frame) then I have to go back to ISO or aperture. Since I am already at my lowest ISO, I will 'stop down' my aperture until 1/200th of a second(my sync speed) is underexposing the subject. So, now, we'll say I'm at ISO 200, 1/200th of a second shutter speed, f/8 for my aperture, and my subject is underexposed by about a stop. Now, I will add the flash to bring my subject up to the proper exposure level.

So, it's not a matter of 'underexposing all three'. It's more a matter of coordinating all three settings, plus a flash, to achieve your desired results. Since often changing one thing will impact another part of your shot, it's important to know how they interact and when to use what to achieve the results you want.

 

[Derrel]

A "stop" in modern American English means ONE FULL "value" on the Exposure Value scales for lens aperture; for shutter speed; and for film ISO or for Digital Sensor Gain:

Examples of FULL lens aperture values or f/stops are: f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/64, f/128, f/256. (13 discrete FULL f/stops)

Examples of full shutter speed times: 1/4000, 1/2000, 1/1000, 1/500, 1/250, 1/125, 1/60, 1/30, 1/15, 1/8, 1/4, 1/2, 1 second. (13 discrete shutter speed values, each one FULL 'stop' different)

Examples of Full ISO values: 51,200; 25,600, 12,800; 6,400; 3,200; 1,600, 800, 400,200, 100, 50, 25, 12. (13 different ISO values or Digital Gain values, listed in Full-stop differences)

 

[Helen B]

Examples of FULL lens aperture values or f/stops are: f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/64, f/128, f/256. (13 discrete FULL f/stops)

I'm sure it's just an oversight because I know that you know this, but you missed f/45, f/90 etc - you switched to two-stop changes after f/32.

Best,
Helen

 

[Derrel]

Examples of FULL lens aperture values or f/stops are: f/1.4, f/2, f/2.8, f/4, f/5.6, f/8, f/11, f/16, f/22, f/32, f/64, f/128, f/256. (13 discrete FULL f/stops)

I'm sure it's just an oversight because I know that you know this, but you missed f/45, f/90 etc - you switched to two-stop changes after f/32.

Best,
Helen

Thanks Helen,
NO, it's not an oversight...I'd simply been drinking wine much of the evening and I was, well, pretty well hammered...but thanks for giving me the benefit of the doubt!!!!

 

[gsgary]

Thank you! So when people say they are going to underexpose by a stop... they could mean they can do it by either aperture, ISO or shutterspeed... ?

If a person wanted to, or needed to, a one-stop underexposure could be accomplished by lowering the ISO 1/3 of a stop, by speeding the shutter up 1/3 of a value, and by closing the lens down 1/3 of an f/stop.

Just so i'm 100% clear... when someone needs to underexpose a stop, are they doing just one of these examples or all??
ex. Lower the ISO a stop + speed up the shutter a value a stop + close down the lens a stop = underexposing a stop.

If you did all 3 you would be 3 stops under, it's very simple

 

[gsgary]

Just to try and help you understand more, when you are in your semi-auto modes ( like Av and Tv mode on Canon, and uhhh I think S and A?? modes on Nikon??? ) if you are in lets say Shutter Priority, if you adjust the exposure comp for an underexposure, the camera will stop down the lens because it knows you want the shutter speed to be what you chose. If in Aperture priority mode, it will speed up the shutter. Both would be done by "Underexposing" on the exposure comp wheel, but would be achieved by different settings.

I shoot 100% manual. So to stop down an exposure, would I need to underexpose all three? (ISO, Shutter, Aperture)

You need to go on a photography coarse as soon as possible

 

[gsgary]

I love it when Sabrina posts, we never get less than 4 pages

 

[jwbryson1]

A "stop" is simply the de facto unit for exposure. It's nothing more than a doubling or halving of the value. Aperture, shutter-speed and ISO are all commonly expressed in stops. A change from 1/125 to 1/250 is a change in shutter-speed of 1 stop. Needing one stop more light would be the opposite, say a change from 1/1000 to 1/500 of a second, or from f8 to f5.6, or even ISO 400 to ISO 200.

Not to split hairs or "call you out" so to speak, but rather to cement my understanding of ISO, above you suggest adjusting ISO from 400 to 200 to get "one stop more of light." Wouldn't you change the ISO from 400 to 800to get one more stop of light?

Please clarify. Thanks.

 

[Overread]

I love it when Sabrina posts, we never get less than 4 pages

I just get jealous - she always gets way more and way better replies than I ever did

you guys just like her too darn much!

 

[Derrel]

Could SabrinaO be our forum's next erose????

 

[tirediron]

Wouldn't you change the ISO from 400 to 800to get one more stop of light?

Please clarify. Thanks.

Oops; my mistake. Thanks for pointing that out. Changing from 400 to 800 would indeed give you the equivalent of one stop more light.

 

[GooniesNeverSayDie11]

I have a question, sort of off topic, but I think that it begs to be asked. Unless you are shooting with strobes, what is your purpose for shooting full manual? If you are using the cameras light meter and adjusting until it says you have a "proper exposure," it kind of defeats the purpose of running full manual. If you were shooting in semi auto modes, it would make it a little easier to decide which element you would adjust in order to underexpose. ( As explained in my earlier post )

 

[Compaq]

If you want to stop down your exposure (I'll interpret that as underexposing, measured in stops), that does not imply stopping down on the entire exposure triangle. Let's say that you have

f/8
1/200th
ISO 200

One stop less light could be accomplished by

f/11
I/200th
ISO 200

f/8
1/400th
ISO 200

f/8
1/200th
ISO 100

Get it? When "counting stops", it's all about halving one thing and double the other. When in manual, you set your ISO and then, for example, your needed aperture (DOP). You then scroll until you get that dot in the middle of the thing you're metering off = "correct exposure". To underexposure the image, simply choose a shutter speed a bit faster than what your camera says to be "correct". Example:

your camera says 1/125th of a second, but you want to underexposure by two stops (perhaps you're taking a sunset shot), you scroll your dot thingy until you've got a shutter soeed of 1/30th of a second = two stops less light = four times less light than 1/125th.

Once you get that "AHHHHHHHH, I GET IT NOOOOW, OFC!!!", everything falls into place. Well, not everything, but quite much.

 

[Vtec44]

Unless you are shooting with strobes, what is your purpose for shooting full manual?

I'm also curious to why as well.

 

[Kerbouchard]

I have a question, sort of off topic, but I think that it begs to be asked. Unless you are shooting with strobes, what is your purpose for shooting full manual? If you are using the cameras light meter and adjusting until it says you have a "proper exposure," it kind of defeats the purpose of running full manual. If you were shooting in semi auto modes, it would make it a little easier to decide which element you would adjust in order to underexpose. ( As explained in my earlier post )

Why would anybody use the camera meter and then adjust their shutter speed/aperture/iso to zero out the camera meter? I agree that would defeat the purpose of shooting in manual, but then again, you would very rarely want your camera meter to be zeroed out when you are using flash.

I guess if you want to readjust your exposure compensation every time you change the framing or a different subject with a different color shirt on is the frame, you could accomplish the same thing in one of the automated modes, but that would be a pain in the neck.

Much easier to just shoot in manual.