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Old Jul 4, 2006, 4:27 PM   #1
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I took a series of photos with different EV settings. I wanted to see how they translaged into lighter/darker images. We went on vacation and I had the camera set at -0.3 EV hoping to "lighten" up the images. Nearly all the images were darker, and there were exceptions. Why doesnt the setting on the camera set at say -0.7 (i have it set to 1/3 EV valutes in menu), translate to 7 all the time? Why does -1.0 EV end up at -1.33 EV on the picture, making it way too dark?



ALL shots taken in Aperture mode, same aperture, different zoom or shutter speeds (obviously).Ibelieve set at f8.0. So it is not on AUTO or other program modes.



Glitch in the electronics of the camera? Warranty or just "adjust" according to it's pecularity?



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Old Jul 4, 2006, 4:29 PM   #2
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Next picture.. ps all data can be seen in the EXIF info embedded in the picture.
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Old Jul 4, 2006, 4:30 PM   #3
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Old Jul 4, 2006, 4:32 PM   #4
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Last picture. Promise the horse. Picture was taken at 0.0 EV setting on the camera before I took it. But that is not what the EXIF says it was. Very odd.

This seems to be a very well exposed picture overall.
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Old Jul 4, 2006, 5:00 PM   #5
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The Winemaker wrote:
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I took a series of photos with different EV settings. I wanted to see how they translaged into lighter/darker images. We went on vacation and I had the camera set at -0.3 EV hoping to "lighten" up the images. Nearly all the images were darker, and there were exceptions. Why doesnt the setting on the camera set at say -0.7 (i have it set to 1/3 EV valutes in menu), translate to 7 all the time? Why does -1.0 EV end up at -1.33 EV on the picture, making it way too dark?
A - EV setting is designed to make the images darker (not lighter).

Exposure Compensation lets you alter the way a camera's autoexposure/metering algorithms expose animage (brighten or darken it compared to the way the camera meteredthe 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 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 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.

Correct Exposure comes down to the amount of light, the ISO speed, and the aperture. A variety of combinations will produce identical exposure. You only need to 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). If you brighten the exposure for one part, the rest may be overexposed.

If your subject is much brighter than the rest of the image, 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.


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Old Jul 5, 2006, 12:02 AM   #6
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What you say, Jim is very true. I have been photographing many years, going back to the late 1960's and adjusting the EV of the camera is sometimes of great benefit depending on what the subject is you are trying to correctly expose. On spot metering you can get a little more 'finess' by setting things manual.

What I really don't like is that this Nikon D50 is not taking pictures according to what I have set it for on the camera beforehand. Notice on the first picture of Samantha. that is 0/0 meaning I set the camera at +/- 0.0 EV so it is not biased to under or over exposure.BUT that is not what the reulting picture EXIF data shows. It shows it being taken at -0.33 EV. The next picture is taken at -0.3 EV on the camera and the last picture of Promise (horse) I had set the camera back to 0.0 EV (neither minus or plus compensations. NOW look at the camera picutre EV value in the EXIF info. it's at -0.3 EV How come? How come I set the camera to 0 EV and it shot it at -0.33 EV? Why is the camera NOT shooting it at the setting I have "PRE-SET" before hand? That is my biggest question.


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Old Jul 5, 2006, 4:04 AM   #7
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The EXIF data has been stripped from the posted pictures so no-one can see it. Can you post it separately or a link to the picture with EXIF intact?

Keith.
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Old Jul 5, 2006, 9:54 AM   #8
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keith1200rs wrote:
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The EXIF data has been stripped from the posted pictures so no-one can see it. Can you post it separately or a link to the picture with EXIF intact?

Keith.
Keith, the EXIF isn't stripped (I can see it fine using Opanda IExif with Internet Explorer).

I can't see it with IExif in Firefox. But, that's just a problem with my install of it (something got messed up a while back and I'm still trying to get it straigthtened out). I probably need to uninstallboth types ofIExif (the one fir Firefox and the one thatworks in Microsoft Explorer and Microsoft Internet Explorer) and reinstall both again. I think I accidently installed theFirefox pluginbefore making sure I had the main Explorer program installed first a while back, causing my issues.






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Old Jul 5, 2006, 10:03 AM   #9
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The Winemaker wrote:
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What I really don't like is that this Nikon D50 is not taking pictures according to what I have set it for on the camera beforehand.
I've just about given up on how Nikon reports information in the EXIF. It's more likely just a reporting problem (or viewer interpretation issue), versus whatthe camera is actually doing. They tend to putdata in the makernotes section for some things that most EXIF readers don't interpret properly (for example, the ISO speed).

One way you could probably tell would be to go manual exposure and see what you're metering for needed shutter speed with the scale centered for a given aperture. Then, go to a mode like Aperture Priority and see if you're still getting the same shutter speeds with no Exposure Compensaton, and the expected change in shutter speed using Exposure Compensation in small increments.

I sometimes see variations between EXIF readers with my Konica Minolta cameras too. For example, if I use a -2/3 stop for Exposure Compensation, sometimes I see it reported as -0.5, and other readers may report it as -0.6 or -0.7.

Raw files get very interesting. When I look at ACR, I sometimes see it reporting 1 or 2 stops of Exposure Compensation, when I've got none at all set taking the photo. Very Odd. It's probably got something to do with the relationshiop with ISO sensitivty and the way the camera's amplifying the signal to simulate a given ISO speed (that's my guess anyway), since there are two ways to do it (amplify the signal prior to the analog to digital converter, or increase the values in the raw file in the image processing pipeline).

Do you see the same thing using Nikon's software to view the camera settings used for a photo, and are you using a fixed ISO speed or Auto ISO?

Nikon's software should be able to interpret the data correctly, if Nikon is using something unique in the makernotes section (which most readers won't know how to interpret, since Nikon doesn't publish the specifications forthis data).

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Old Jul 5, 2006, 10:39 AM   #10
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Strange, I use Firefox and Opanda and it works on other photos on the forum, and other forums - I don't know why it doesn't like those particulr photos.

Keith.

JimC wrote
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keith1200rs wrote:
Quote:
The EXIF data has been stripped from the posted pictures so no-one can see it. Can you post it separately or a link to the picture with EXIF intact?

Keith.
Keith, the EXIF isn't stripped (I can see it fine using Opanda IExif with Internet Explorer).

I can't see it with IExif in Firefox. But, that's just a problem with my install of it (something got messed up a while back and I'm still trying to get it straigthtened out). I probably need to uninstallboth types ofIExif (the one fir Firefox and the one thatworks in Microsoft Explorer and Microsoft Internet Explorer) and reinstall both again. I think I accidently installed theFirefox pluginbefore making sure I had the main Explorer program installed first a while back, causing my issues.





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