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Old Aug 18, 2010, 3:07 AM   #1
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Default JPG Image details and CS5 detection differs?

Hello,

I'm rather confused about the following. I have taken a few shots to go for HDR attempts.

Upon shooting, I used a tripod, put the auto-bracket on +1, and took photos with exposures of -2 to +2.

When I look at the JPG detail / summary information (or however it's called), you can see all the statistics like when it's taken, the camera used, the F-stop and such. I don't know what the English word is, as I'm Dutch and use the Dutch Windows version. But there's also something like, in my best attempt to translate it, 'Exposure Bias'. When I check my details, it says -2, -1, 0, +1, +2 and so on, and I think that's quite good, as I took them that way.

In CS5, the HDR Photomerge says that my EV is +0,32, and on the other +0,32 as well, and the last 3 0 , -1, and -2. Is there something that CS5 does to correct something, or is it me that did something wrong?

When I open the same shots with Photomatix, it gives again other exposure values than my photo-details panel says. Since I took a whole lot, and I open them all together, it gives again the comment that there are equal EV-photos in the list, but some at least have -2 until +2.

Please help this confused guy out
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Old Aug 18, 2010, 10:40 AM   #2
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Exposure Bias=Exposure Compensation.

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Old Aug 18, 2010, 3:49 PM   #3
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If I usnderstand correctly, I think the answer is that the autobracketing is set separately from the exposure value.
If you have set an exposure value of -.5 and take a single shot, that is what the camera will use as the setting. If you take a bracketed series, the EV you set is used as the middle exposure, and the others are calculated from that.

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Old Aug 19, 2010, 1:57 AM   #4
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Thanks for your input, but I"m not sure if I still understand it properly. In my case, I took a few photos, in which I put the Exposure Compensation on +1, then on 0, and then on -1. Each time I use autobracketing as well, which is on +1.

I thought that means that I'd have a photo range from +2 until -2. When I save the photos to the computer, I can check the properties and summary of the photos, and they all have a certain Exposure Compensation, but yet, when loading in CS5, it gives other EV results, or am I looking at the wrong thing?
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Old Aug 19, 2010, 8:27 AM   #5
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Without knowing your camera, I couldn't say for certain, but with some models, the EV steps for autobracketing, as well as the number of exposures for the series, are set separately in the menu.

If you set EC to +1 and use bracketing at 1 stop, you should get a 3-shot series of 0,+1,+2. With EC set to 0, the series would be -1, 0,+1. EC of -1 would give -2,-1, 0.
If I understand what you are getting at, this is what you are doing. The middle set, though, is redundant-each of these exposure is duplicated in one of the others.

If this is what you are doing, I don't understand why CS5 is not giving you the correct information. Are the pictures taken in Raw or jpeg? If in jpeg, you should try looking at the Exif info with another Exif reader.

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Old Aug 19, 2010, 9:19 AM   #6
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I have the Panny FZ38. The autobracketing can be set to max +1.

The Exif info from windows seems to be correct (the way I took them), but both CS5 and Photomatix (tried this earlier this day as well) give other information.

But with them giving other values than they actually are, isn't that a problem for creating for instance HDR photos?

Oh and I take the pictures in JPEG.

If you want, I can post a photo in which all 3 photos give other information.
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Old Aug 19, 2010, 8:58 PM   #7
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As long as the picture sequence is in order, the software should be able to create the HDR image from the actual exposures - the Exif numbers shouldn't affect it. It does seem curious, though.
Maybe someone familiar with the camera has a better idea what is going on. Hav you asked in the Panasonic forum?

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Old Aug 22, 2010, 7:29 AM   #8
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I have not asked it yet in the Panny forum itself, as I thought this was more a 'general discussion' thing that might have been noticed by other users as well. Since I'm on a different computer now, I can't post the photos that give total different values, but I will upload a few when I got the chance, want to get this 'myth' busted ;-)
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