Meaning of the term "pushed by 1 EV" in the context of Digital Photography
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Stoo
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"EV" stands for Exposure Value. It isn't unique to digital photography... it applies to film as well. It simply means that you are changing one of the parameters used to control the exposure... increase/decrease the shutter speed, or open up/close down an f-stop, or adjusting the ISO by one step. Each has a (more or less) equivalent effect on the exposure, although other things could be effected, like depth of field, or freezing motion.
So "pushing 1 EV" means than one of these controls on the camera has been changed my one "stop" or unit.
By changing any one of these items, you can change the exposure and control the light entering your camera to your benefit. For example, you can decrease the aperture (bigger number = smaller hole) by two stops to gain depth of field when shooting macro. But you will need to decrease (i.e slow down) the shutter speed by an equivalent two stops, or the image will be underexposed (assuming it was properly exposed initially). If the slower shutter speed puts you at risk of having a blurred image, then you could leave the shutter speed where it was, and change the ISO ("film speed") to a faster speed (again, two stops!) and have the same effect.... more or less.
It really only applies when shooting in manual exposure... well, mostly anyway.
So "pushing 1 EV" means than one of these controls on the camera has been changed my one "stop" or unit.
By changing any one of these items, you can change the exposure and control the light entering your camera to your benefit. For example, you can decrease the aperture (bigger number = smaller hole) by two stops to gain depth of field when shooting macro. But you will need to decrease (i.e slow down) the shutter speed by an equivalent two stops, or the image will be underexposed (assuming it was properly exposed initially). If the slower shutter speed puts you at risk of having a blurred image, then you could leave the shutter speed where it was, and change the ISO ("film speed") to a faster speed (again, two stops!) and have the same effect.... more or less.
It really only applies when shooting in manual exposure... well, mostly anyway.
OP
Thank you for the clarification. I understand where the EV comes from (f-stop and Shutter speed) but not sure the whole term when used with the word "pushed." I saw the term with the word pushed in a discussion about ISO and using "low" ISO. The people there were saying to "push" the EV instead of using a low ISO (100).
I vaguely remember the term "pushing" the film way back then in the film days that referred to making a film of certain speed (I think higher ISO) to work as if it were another speed film (I don't remember the whole thing since it has been ages since I have used film).
I vaguely remember the term "pushing" the film way back then in the film days that referred to making a film of certain speed (I think higher ISO) to work as if it were another speed film (I don't remember the whole thing since it has been ages since I have used film).
In this case will be exposure compensation. So set Ev = -1 to get the picture darker as opposed of increasing the ISO
[SIZE=-1]In the days of shooting film you'd choose a film with an ISO rating for what you though the majority of the lighting conditions would be so you could get properly exposed shots. You also choose the film based on it's color capturing characteristics and grain characteristics. More often you'd take what ever the paper or magazine gave you and you dealt with it. When you developed that negative, the chemical and time combinations where based on the film's type and ISO setting. You could push/pull film process by setting a film rated ISO at a higher or lower ISO setting. This changed the negative development times. But there was a catch. You could not change the ISO settings back and forth on a roll while shooting as all the pictures would not develop correctly because the negative development process was based on a one ISO setting. (you could shoot 1/2 a roll at ISO 'X' and the other half at ISO 'y', cut the film and develop each half of the film, but you could not easily bounce around the ISO ranges and then use one negative development process).
So increasing/decreasing the EV was a [/SIZE]quick way to get a shot without having to change films. The trade off was a loss of detail and grain. Before there was Photoshop you'd deal with any minor exposure issues in the print processing. It was very time consuming.[SIZE=-1]
By increasing/decreasing the EV you are under/over exposing a shot by 'x' increments of shutter speed / f-stop combinations at the same ISO rather than increasing the ISO to get the same shutter speed / f-stop for the given exposure.
example:
[/SIZE]Your exposure at ISO 100 is f/4 and 1/15. Increasing the ISO to 400 allows 2 stops higher shutter speed (effectively f/4 and 1/60). The total exposure remains the same, though. The loss of light due to the high shutter speed is offset by the higher sensitivity of the sensor at ISO 400. So [SIZE=-1]keeping the ISO at 100, and dialing in -2 EV of exposure compensation gets you f/4 and 1/60, but you'll be 2 stops underexposed.
The trade off (in the above example) is that you will be underexposing the picture and you will loose detail in the darker areas of the photo.
With todays digital cameras you are able to pull that detail out of the photo easily during post processing by using any of the major pp software packages. The control is even better when you shoot in RAW mode and pp.
Sorry if this is TMI.
[/SIZE]
So increasing/decreasing the EV was a [/SIZE]quick way to get a shot without having to change films. The trade off was a loss of detail and grain. Before there was Photoshop you'd deal with any minor exposure issues in the print processing. It was very time consuming.[SIZE=-1]
By increasing/decreasing the EV you are under/over exposing a shot by 'x' increments of shutter speed / f-stop combinations at the same ISO rather than increasing the ISO to get the same shutter speed / f-stop for the given exposure.
example:
[/SIZE]Your exposure at ISO 100 is f/4 and 1/15. Increasing the ISO to 400 allows 2 stops higher shutter speed (effectively f/4 and 1/60). The total exposure remains the same, though. The loss of light due to the high shutter speed is offset by the higher sensitivity of the sensor at ISO 400. So [SIZE=-1]keeping the ISO at 100, and dialing in -2 EV of exposure compensation gets you f/4 and 1/60, but you'll be 2 stops underexposed.
The trade off (in the above example) is that you will be underexposing the picture and you will loose detail in the darker areas of the photo.
With todays digital cameras you are able to pull that detail out of the photo easily during post processing by using any of the major pp software packages. The control is even better when you shoot in RAW mode and pp.
Sorry if this is TMI.
[/SIZE]
The only time I've ever heard of "pushing" the EV it was a reference to increasing the EV by 1 stop. EV+1
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