External Flash n00b question. (580EX)

[SAZABI]

I just bought an external flash and this is my 1st external flash so I don't really know how to use it :o

When I put the camera in "M" mode, things seem to work fine as the flash will adjust its power to fit the setting.

However, if I put the camera in "Av" mode or "Tv" mode, it seems that the camera and the flash is not working well together. For example, in Av mode, i put the aperture in f4, but then the shutter will automatically selected to be 0.3". It is impossible to take a picture of people with 0.3 shutter.....

Can anyone tell me how it works under Av mode or Tv mode?

[rent]

this is probably one of the most frequently asked flash questions. in a nutshell, in AV/TV the camera sets exposure to properly expose the background while the flash outputs just enough light to properly expose the foreground.

please check out the flash sticky for more info.

-alex

[SAZABI]

thx, i read that flash bible and got more info.

thx for the help :)

[scottbergerphoto]

In Av and Tv, the camera is automatically trying to expose for the ambient light. In a dark room requiring flash it will correctly choose a slow shutter speed. In M Mode. you select the shutter speed. If you follow what the meter says you will wind uo with the same as Av or Tv. You're job in M Mode is to determine how much ambient light you want to record in exchange for a slower shutter speed. Just remember that the camera meter is always trying to meter the ambient light.

[robertwgross]

Just remember that the camera meter is always trying to meter the ambient light.

Let me add that in some modes, the camera meter can only work on ambient light and show you a full-time steady-state exposure solution in the viewfinder.

In other modes, the camera's meter can determine the flash exposure, but it only does that accurately in the tiny split second between the pre-flash and the main flash. So it doesn't really have the time to show you what it is doing until it is already done.

---Bob Gross---

[scottbergerphoto]

Bob, having no idea what you were trying to convey in your last post :shock: , let me say this for clarification. The camera meter in all modes gives you ambient light readings only. The camera meter never gives you a visual indication of the results of its flash metering until you see the actual picture or histogram. There is nothing analogous to the meter in the viewfinder for flash metering. The meter represented in the viewfinder is only for ambient lighting. Flash metering takes place, but its results are not displayed prior to the image being taken.

[robertwgross]

Yes, Scott, that is what I was saying also.

---Bob Gross---

[SAZABI]

someone care to explain further what "ambient light" is?


hee... sorry for being such a newb.... :o

[tim]

someone care to explain further what "ambient light" is?

hee... sorry for being such a newb.... :o

http://www.tfd.com/ambient

It means light that just happens to be there, rather than light you placed there. eg outside you'd call sublight ambient if you're using a flash. You might call room lighting ambient if you're using a flash.

[SAZABI]

okie~

thank you all for the input and help. now, it is time to practice.

Thx again~!