I am new to photography, and I just purchased the Canon G11. I am having the hardest time to learn how to determine what the AV/TV values need to be, in conjunction with ISO speed. I understand the reciprocity between AV/TV, which means that the higher the aperture value (the smaller the actual aperture size), the slower the shutter speed you can/should use because of the lessened amount of light entering the camera's aperture, and vice versa.

But how do you determine what combination of the two to use? My goal is to be able to turn on M--because I haven't gotten much success with AV Priority or TV Priority--and know what both should be with minor adjustments, and capture a solid picture. Is this a farfetched idea? Is this not how it is done? Also, with AV/TV Priority, how/when do you use them effectively.

I have seen some fantastic pictures come from the G11--so great in fact that I would have easily confused them for DSLR pictures --so I know it is not the camera - I recognize that it is my inexperience: I want to learn, not angrily demand a refund because it did not reproduce the Mona Lisa just by turning it on.

I was out last night and attempted to take pictures of people around a fire using the ambient light, and they always came up very blurry. I know to increase the shutter speed and aperture size (smaller AV) because of the situation (I did not have a tripod to allow for a longer shutter time).

I know that aperture alters the DOF, I experimented with my keyboard, and learned the (obvious to all of you) fact that the smaller the AV, the shallower the DOF, seen when i focused on a key in the middle of the keyboard and the further out, either in the fore- or background, became out of focus. And then obviously, when I cranked it up to f8, the entire keyboard came into focus.

Lastly, with ISO, what do you base it at? I am new to not using the flash so the whole concept is new to me. I used to work as a photo tech at Walgreens just simply processing the images, and I noticed that most of the film rolls we got were ISO 200/400, but I never understand what that meant (lol, yea they trained me well). Now, I realize that you need to up the ISO at night/limited light, and with each increase, you risk noise, especially above 800. What are your guides? What I mean by that: where do you default the ISO to depending on the light conditions? Is it bad to crank it straight to 16/3200 if it is extremely dark out, and then keep it around 100 during the day, and around 4/800 around slightly lowered lighting, such as dawn/dusk, indoor lighting?

Then, lastly, how do you combine the three? Because I know that with a larger aperture (smaller AV), then a lessened ISO, yet faster shutter speed are used.

Like I said, I am new to photography, but I have researched the hell out of it, and this is the single biggest issue that is holding me back from attaining some great shots. I realize I have a good eye for artistic shots, but I can't for the life of me seem to capture them. I kinda feel like a highly educated researcher that has a wealth of knowledge of the subject, but no real-life, actual experience in it to make it applicable. (Sadly, this is not unknown to "academics," but that is a whole other debate :))

And also, I did not try to explain everything as detailed as I did to clarify it for you. I know you know. I just wanted to show you that I know what I am talking about, and most importantly to me, if any of my explanations--what I view as correct from my personal reading up on the subject--are wrong, correct me so that I can relearn what the hell I am doing, correctly.

Thank you very much for enduring this essay. I just want to overcome my ineptitude with a camera. :)

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I'm a 22 year old cadet ready to graduate and serve as a platoon leader in the US Army that has an extremely voracious apetite for backpacking and adventure. I am also finally feeding my passion for photography while working on the fluency of my two languages other than English: Spanish and Arabic.