Flash, aperture, shutter speed and sync speeds

Will James

Will James

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Hi,

I got a 50 1.8 a few days ago and thought it would be better for using flash indoors obviously because of the wide aperture potential. To my understanding, I thought that when flash is used, partciularly at very wide apertures, shutter speeds would be able to be increased because the flash is producing more light.

However, when I was in P or Av modes, with the pop-up flash up, the camera would set it to f3.2 at 1/20th sec (or thereabouts), meaning that I couldnt shoot handheld. Basically I'm wondering why the shutter speeds aren't much higher when I'm using pop-up flash?

Is it to do with the flash sync speed custom function? I'm also trying to get my head around this too and getting very confused! I'm looking to do birthday parties and possibly nightclub/night promotor photography throughout the summer - but I'm so confused right now.

Any help will be appreciated,

Thanks for reading,
Will.
 
In AV mode the camera will meter for ambient and use flash for fill. set the camera in manual and choose the shutter speed and aperture that you want and the E-TTL will adjust the flash power to give correct exposure.
 
Ah I see, I was really confused as to why it wouldn't go above 1/20th. Also, I've just noticed there's a setting for flash sync speed to set between 1/60-1/200 - that would help the problem I guess?

Thanks for the tip, I'll play around with manual :)
 
Woah that is meaty, I've saved it to my bookmarks for when my brain is able to read at least some of it :L

Thanks very much for the help Mike
 
Will James said:
Ah I see, I was really confused as to why it wouldn't go above 1/20th. Also, I've just noticed there's a setting for flash sync speed to set between 1/60-1/200 - that would help the problem I guess?

Thanks for the tip, I'll play around with manual :)
Click to expand...

There will also be a setting to lock the shutter speed at max. sync in Av mode.
 
Will James said:
Hi,

I got a 50 1.8 a few days ago and thought it would be better for using flash indoors obviously because of the wide aperture potential. To my understanding, I thought that when flash is used, partciularly at very wide apertures, shutter speeds would be able to be increased because the flash is producing more light.

However, when I was in P or Av modes, with the pop-up flash up, the camera would set it to f3.2 at 1/20th sec (or thereabouts), meaning that I couldnt shoot handheld. Basically I'm wondering why the shutter speeds aren't much higher when I'm using pop-up flash?

Is it to do with the flash sync speed custom function? I'm also trying to get my head around this too and getting very confused! I'm looking to do birthday parties and possibly nightclub/night promotor photography throughout the summer - but I'm so confused right now.

Any help will be appreciated,

Thanks for reading,
Will.
Click to expand...

The honest answer to your question Will is you need to bone up on exposure and how flash interacts with ambient light in this situation. There's a good good by Syl Arena, the Speedliter's Handbook - £18 Amazon.

Basically the issue you have here is nothing to do with the lens, and what you appear to be trying to do is at odds with the usual way an f/1.8 lens would be used. The idea of having a really low f/number lens in low light is usually so you don't have to use flash at all.

If you shoot on Av, as mentioned above the camera will adjust the shutter speed to balance the ambient with the flash. In P, it will try to do the same, but will not drop below 1/60sec so that doesn't sound right.
 
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