General question about Aperture/Shutter speed

[TMR Design]

I know that for some this is a silly question but I have real background in photography and never used manual SLR's in the past so my only experience is with digital camera. I have been working with my A620 and never use Program or Auto anymore. I must admit though, that at times I get confused as to settings to use and in which situations to use them.

For instance, if I were taking an outdoor shot how do I know what is the ideal aperture? I understand about depth of field and closeups but don't fully understand how to work with it in other situations where you could choose an aperture and the camera will set the appropriate shutter speed. When there is enough light for many different combinations how do you know?
On ther flip side, when many shutter speeds will work and the camera sets aperture, how do you know what is best? I know that playing and shooting will sometimes give me all these answers, many of which I have gotten but I would like to undertand it from the photographers perspective, understanding lighting and how fast the shutter should be. Just with aperture, I have an understanding of how to shoot subjects that are moving or fast moving objects but when there is no movement how do you know what speed to use?

Thanks.
Robert

[Jon]

You can choose an aperture either for depth of field or to force the shutter speed in the direction you want. For instance, you'll choose maximum aperture if you want to isolate your subject, or if you're trying to get the fastest available shutter speed. If you want greater DoF, or if you want a long exposure (to get motion blur, say), you'll stop down as far as possible. Using the aperture for this ensures that you'll get the fastest/slowest shutter speed that will give you a good exposure.

If you're in a situation where you know you want a specific shutter speed, say to reduce camera shake problems or to allow a certain amount, but only so much, subject motion to be captured (prop aircraft and helicopters are good examples - too fast a shutter speed and you'll freeze the prop; too slow and it'll disappear) you can set the shutter speed and take the aperture that falls out.

There are other cases, but most good photography books (Bryan Peterson's Understanding Exposure is popular here) will explain the selection process in more detail.

[TMR Design]

Thank you very much Jon

[TMR Design]

Hi Jon,

I see you are also using an A620. What types of gadgets do you use? Any cool toys or add-ons you use or recommend?
I currently have the 58mm Canon converter tube and a UV and Polarizing filter but have not had much experience with them yet. I am still trying to figure out how to deal with the fact that the viewfinder sees the top of the barrel and in bright sunlight I am finding difficulty in shielding the LCD from the sun. At times it gets washed out and you really have to wrok to find an angle or hand position to see the LCD.

Is there a flip out shade of some kind that works on an A620 with the tilt/swivel display?

[Jon]

I don't have any accessories for it. If I'm going to be doing anything fancy, I use one of the DSLRs.