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can you use exposure instead of aperture, shutter and iso
Aperture, shutter and iso are used to control the amount of light the sensor exposes to. so does that mean it the photo is too dark, you can change the EV exposure thing instead of higher iso, bigger aperture or longer speed?..

Comments (9)

Of course you can..

Camera software will decide what component of these 3(or combination) it will change for you. If you want to check what it did, you can open exif of both files and compare.http://www.stan-pustylnik.smugmug.com..

Comment #1

If it does, how come no one really talk about the EV thing. most peopel just talk about stop. if the EV thing does the job, then why need the others unless you want some kind of special effect like depth of field?..

Comment #2

There is no exposure compensation if you're using manual exposure. Your shutter speed and aperture settings take the place of it..

If you're using non-manual modes, then Exposure Compensation is changing aperture or shutter speed..

The meter in the camera's viewfinder is designed to let you know if your settings are going to result in a darker or brighter exposure, compared to the way the camera's metering thinks it should be exposed. In manual exposure mode, your camera settings for iso speed, aperture and iso speed impact exposure..

When you are shooting in non-manual modes, this meter is used for a feature called Exposure Compensation. If you set the camera so that the pointer is higher than zero, it will take a brighter exposure than the camera would have used by default. If it's set to a -EV value, it will expose it darker than the metering thinks is needed..

If you're shooting in Manual Exposure mode, there is no Exposure Compensation (because your aperture and shutter speed settings take the place of it since you're controlling both of these variables, although most cameras have a meter that shows you how your settings are impacting exposure)..

Exposure Compensation lets you alter the way a camera's autoexposure/metering algorithms expose an image (brighten or darken it compared to the way the camera metered the scene). It's one of my most frequently used settings on most cameras..

A +EV value gives you a brighter exposure. The camera uses a slower shutter speed and/or larger aperture (smaller f/stop number) to get a brighter exposure, compared to what the camera's autoexposure/metering algorithms would have selected..

A -EV value gives you a darker exposure. The camera uses a faster shutter speed and/or smaller aperture (higher f/stop number) to get a darker exposure, compared to what the camera's autoexposure/metering algorithms would have selected..

If you're in Av Mode (Aperture Priority) and use Exposure Compensation, the camera will vary the shutter speed (since you're setting the aperture). If you're using Tv (Shutter Priority) mode and use Exposure Compensation, the camera will vary the Aperture (since you're controlling the shutter speed)..

If you're in Auto (or other similar modes), the camera may vary aperture or shutter speed when you use Exposure Compensation. In low light, since your aperture is already wide open, it varies shutter speed if you use a -EV setting..

If you're shooting in Manual Exposure mode, there is no Exposure Compensation (because your aperture and shutter speed settings take the place of it since you're controlling both)..

Correct Exposure comes down to the amount of light, the ISO speed, the shutter speed, and the aperture. A variety of combinations will produce identical exposure..

You use Exposure Compensation if you want a brighter or darker image compared to what the camera's metering would normally give you in the same conditions..

An example of when you may want to use a +EV setting is for a backlit subject, where the subject would normally be much darker than the rest of the image. Since the camera has a limited dynamic range, it doesn't know that you want the dark subject exposed properly (at the expense of the rest of the image). So, you can make the darker subject brighter for correct exposure (which might cause the rest of the scene to be overexposed some)..

If your subject is much brighter than the rest of the image (for example, direct sunlight hitting your subject, even though most of the photo is in shadows), you may want to use a -EV setting for Exposure Compensation so that your subject is not overexposed (making the rest of the image darker, too)..

The camera has a limited range of bright to dark that it can capture. So, it makes choices so that most of the iimage is correctly exposed, depending on your metering mode. Sometimes that may not be what you want. That's where exposure compensation comes in..

If you reach the camera's ISO speed limits and your shutter speeds are still slower than desired, you can also use exposure compensation to get faster shutter speeds by deliberately underexposing using a -EV Setting. Then, brighten the images later using software so that they appear to be correctly exposed..

But, this will increase noise levels, just as if the camera had an even higher ISO speed available (especially after you brighten the underexposed images with software), and deliberately underexposing and brightening images later also results in some loss of dynamic range. So, don't use this technique unless you have to..

JimChttp://www.pbase.com/jcockfield..

Comment #3

New_type wrote:.

Aperture, shutter and iso are used to control the amount of light thesensor exposes to. so does that mean it the photo is too dark, youcan change the EV exposure thing instead of higher iso, biggeraperture or longer speed?.

Just to set the facts straight-aperture and shutter speed control the AMOUNT of light that reaches the sensor. iso controls the SENSATIVITY of the sensor to the light that reachs it..

Any camera's metering system assumes that any/all scenes/objects reflect 18% of all the light falling on the scene back to the sensor/meter. the 18% is a correct average reflectance for most scenes. the arises in those scenes that do no reflect 18% of the light OR the subject is part of a scene in which the scene/subject is not reflecting 18% but the other is..

The classic examples given in photography classes are- a white cat on a snowfield, white cat on a coal pile; a black cat on a snow field, black cat on a coal pile..

To get the cat sitting on the opposite color background you HAVE to use exposure compensation..

Depending on the shooting mode you are in the EC can take many forms which were detailed in the reply above. but there is one more possibility that should be mentioned. this occurs in the auto or program modes, not aperture or shutter priority. what the camera can do is to back down the iso setting while leaving the shutter speed and aperture alone. this can occur even if the camera is already set at the lowest iso in the specs. it occured to me when I was shooting apic of a waterfall in among very dark rocks.

And the shutter and fstop were untouched. even though I was shooting at the lowest iso, it detected the white of the waterfall and backed the iso down so that it was not blowing the white water. all that was necessary back in the pc was to hit auto level and the overall brightness of the scene was normal and the histogram was fine but not blown. was I suprised; it was not in the manual either. the camera just did it..

Not all cameras do this. mine is a pentax *istD. what I have since discovered is that if the metering system detects ANY of the 16 meter segments blown and the camera is in auto or program; it will back down the iso until the blown segment is not blown...

Comment #4

Jim has provided a great and detailed explanation below, here's my effort:.

You adjust shutter speed, aperture and ISO to achieve the optimum exposure..

There are many different combinations of these settings that will give exactly the same exposure. For example:ISO 200, 1/60 sec, f/5.6ISO 200, 1/120 sec, f/4ISO 400, 1/120 sec, f/5.6ISO 800, 1/240 sec, f/5.6will all give the same exposure..

You change shutter speed to freeze or blur the subject.You change aperture to vary the depth of field..

You change ISO to allow you to achieve a shutter and aperture combination that you could not otherwise use..

That's an oversimplification, perhaps, but for the purpose of this discussion it should suffice..

Now to your question:.

New_type wrote:.

If it does, how come no one really talk about the EV thing. mostpeopel just talk about stop. if the EV thing does the job, then whyneed the others unless you want some kind of special effect likedepth of field?.

You can change shutter and aperture from shot to shot, very easily..

You can also change ISO from shot to shot, although most likely you would do it less frequently - as you move from one set of lighting conditions to another, perhaps. Having selected the appropriate ISO that you need for the general conditions, you're likely to leave it there and just use shutter and aperture from shot to shot..

If you want or need to achieve a consistent over or under exposure on a series of shots, you would dial in exposure compensation (what you refer to as EV). In particular, you can't deliberately under or over expose using P, S, and A modes - you have to use Manual mode. So one reason for using exposure compensation is to allow the use of P, S or A mode in combination with a deliberate over or under exposure. Another reason is so that you can use Manual mode and centre the needle every time without having to remember to offset on every shot..

But that only works when you want to achieve EXACTLY THE SAME over or under exposure on every shot..

There's no one size fits all answer, because everyone's personal style, and every set of conditions, is different. But in general:- For the overall conditions, you set the ISO.

- Then you might also dial in exposure compensation, again, to suit the overall conditions.- Then, shot by shot, you change shutter speed and aperture..

It doesn't make much sense (IMHO) to make frequent changes to EV compensation (or indeed ISO) to adjust each individual shot. If you want to do that, you would use Manual mode and adjust the other settings so that the needle is more or less off centre..

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Comment #5

Glad this question was asked..

I want to thank all of you for taking the time to explain this subject.You made it very clear and uncomplicated!!.

Thanks again,mead..

Comment #6

And also does that mean in indoor low light condition, I can change the exposure or stop instead of flash?..

Comment #7

New_type wrote:.

And also does that mean in indoor low light condition, I can changethe exposure or stop instead of flash?.

Oh yes, of course you can. But in practice thi smight mean any or all of- an ISO setting so high that unwanted noise starts to show- a shutter speed so slow that subject movement blurs the picture- an aperture so wide that depth of field is too little.- too much detail lost in shadows.

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Comment #8

There is only aperture, shutter speed & iso.

Mark_A..

Comment #9

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This question was taken from a support group/message board and re-posted here so others can learn from it.

 

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