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Old Jan 14, 2004, 7:57 PM   #1
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Default Grrr . . . Drebel Trouble! Does this sound normal? TIA

Hi everyone. First let me say thanks to all of the valuable information this forum has provided leading up to my Drebel purchase.

So I got it and am curious about something that seems strange to me.

When indoors (under good lighting) their seems to be a discrepancy between how the camera measures exposure between Basic and Creative Modes.

For instance, if I take a shot in Basic "No Flash" mode. I get a properly exposed shot with 60 5.6 at 55mm.

When I line up the same shot in Av or TV mode proper exposure requires 25 5.6 at 55mm.

Further, using the flash with creative mode barely effects the metering.

Is this right? If so why? The shots tend to look the same exposure wise. Am I missing something?
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Old Jan 14, 2004, 9:12 PM   #2
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Yes, you're missing how ETTL works in the various modes. ETTL is far too expansive to try to explain in this format. I suggest you read the following link:

http://photonotes.org/articles/eos-flash/

Regarding the difference in metering you saw, again it is beyond the scope of this forum. It has to do with a couple of different things. Not trying to diminish your knowledge of exposure and cameras, Basic mode and P mode are both fully automatic modes where the camera takes complete control and determines what settings to use to take the picture that it THINKS you want. Av mode and Tv mode, allow you to choose either aperature (Av) or shutter speed (Tv) and then the camera chooses the corresponding setting. M mode obviously allows you to choose both shutter speed and aperature for complete control. As good as the meters in cameras are, they are easily fooled by scenes that are not of an overall neutral tonality. The difference between 1/60 @ f/5.6 and 1/25 @ f/5.6 is a bit over 1 stop. In any given scene you can easily have a tonal range of 5-7 tones for a range of +or- 2-3 stops. Also working here is the type of metering involved. The DRebel normally meters using the matrix evaluative mode which is very good about 80% of the scenes. If you use exposure lock, the metering shifts to partial metering and if you shift to M, the meter shifts to a center-weighted averaging mode. Each of those modes have their upsides and downsides. Exposure is daunting at first, but once you get a grasp on it, it becomes much easier.

Here's a link for some basics on exposure

http://www.photo.net/making-photographs/exposure

Hope this helps some
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Old Jan 18, 2004, 10:31 PM   #3
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Thank you very much for the reply.

The links were great and gave me a much better understanding of how exposure is calculated differently between the various modes.

I really appreciate it.
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Old Jan 18, 2004, 10:57 PM   #4
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We're here to help (and ask our own questions too)
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