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Old Jan 31, 2006, 2:55 AM   #1
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Hi there

Not sure if this is the right forum; but: I recently purchased a Canon EOS 5D and decided to write a manual. This forces me to fully explore all options without any preconceived ideas.

In this context, I have now come to a conclusion on which I am very keen to get input from more knowledgeable users of the 5D.

The 5D has several shooting modes including P for Program AE, Tv for Shutter priority and Av for Aperture priority. However, in exploring these three modes I have come to the conclusion that - while they explain a specific 'focus (ie have a stated bias)' - there is no difference in what they actually enable me to do. Each offers the same options to decrease exposure time (with the camera increasing aperture) or increase exposure time (with the camera decreasing aperture). In each of the three modes, my interaction is by the same means of using the Quick Control Dial and has exactly the same effect on what the camera does - which is shift between the shutter speed and aperture of the lens.

Am I correct in this perception or am I missing something?
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Old Jan 31, 2006, 4:25 AM   #2
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The difference is in what the camera will do for the new exposure reading for the next shot. Av will keep the same aperture and reset the shutter time, Tv vice versa, and program will reset both to what the camera thinks best regardless of the last picture taken. While framing a shot there is no difference.
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Old Jan 31, 2006, 10:51 AM   #3
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The exposure will remain the same in all 3 modes, and should result in a perfectly exposed shot, butyour intention of what you want the final captureto look like is what you are controlling.

If you control the aperture (Av), you are controlling the depth of field, and the shutter speed will compensate to give you the perfect exposure for this aperture, but you lose control of the shutter speed.

If you control the shutter speed (Tv),you control the amount of blur in the shot and the aperture will compensate to give you the perfect exposure for this shutter speed but you lose control of the depth of field.

If you allow the camera to decide (P), you control neither.

Don't forget that the ISO setting will allow you further control of all of these combinations. Further to this you can control over or under exposure, for difficult lighting conditions, the list goes on and on.

In conclusion, these modes allow you tocompose the picture the way you want the final image to appear, the camera is controlling the exposure. This is what serious photography is about, control. You decide.
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Old Jan 31, 2006, 1:10 PM   #4
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And if you're going to talk about flash usage, the way the flash is metered is different between the three settings. You'd have to look it up, as I forget how. But I believe it is different.

I *THINK* in AV the flash is assumed to be a fill flash, while in "P" it might be considered the primary light source.

And one uses center weight average metering, but I'm not sure all do by default.

The above description of the differences are spot-on. Nicely written liningiv.

Eric
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Old Jan 31, 2006, 4:24 PM   #5
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peterfisp wrote:
Quote:

I recently purchased a Canon EOS 5D and decided to write a manual.

Did yours not come with one?
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Old Jan 31, 2006, 6:56 PM   #6
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Thanks for this; now I knew all this, I am sure. But could not put it as usefully as jacks did. Thanks for the input.

And, by the way, I can write a manual if I want to.
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Old Feb 1, 2006, 5:34 PM   #7
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These shooting modes have been around since my first film SLR. I don't believe it has changed much if at all. If the 5D is your very first SLR, I guess you should be congratulated on your choice. As for writing a manual, I sort of did that when I got my 20D. I wrote out some index cards with summaries of the things that I wanted handy and could refer to in a jiffy. I have some cards for my 580EX flash as well, since I think it it probably more complicated to use than the camera... :shock:

H
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Old Feb 1, 2006, 7:18 PM   #8
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:|There we go, some positive input again. The one about the manual is to force me to fully explore all aspects of the 5D and photography. I am a very knowledgeable computer user; yet it has taken me several years to fully understand the differences between what I know and what my brother knows (or doesn't know) about computers.

I have used a film camera with great interest before; but not for several years. I have bought a Poloraid PDC2000 after it dropped from about USD5000 to under AUD900 but was extremely disappointed about lack of 'pixels' . I also got close to buying a KM Dynax Mxxum 7D. Then I remembered just how much I love to explore detail. So when the 5D came along, the choice was clear.

Even with my limited understanding, it is already clear that the 5D is an amazing technical device. Anyone buying it would be well advised to attempt to fully understandit, and therefore be able to explore it fully.

I think the Pro who has all the previous knowledge to fall back and rely on will be hard pressed to understand the issues that the relative novice faces.


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Old Feb 3, 2006, 2:48 AM   #9
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Very informative indeed.
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Old Feb 7, 2006, 7:42 PM   #10
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I must once more pay tribute to jacks for his response.

Admitting that I actually posted my question on four different forums, the range and scope of responses is just amazing. While some merely told me what I already knew, that I was confused, others also answered my question (how ever badly put) but none with the punch of jacks.

Thanks again.
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