speedlite help!

[nateMN]

Just received the 430ex II. Read the manual and played around with various settings (high speed sync, second curtain, manual) with the 50mm lens. Still confused.
Searched the forum for answers and each search keeps coming up with "hits" because people's equipment list in the signature...

Changed camera flash mode to E-TTL II. Manual says I should have a little icon in the upper right of the flash display for recognizing the image sensor size, no icon.

Took two pictures, one with flash one w/o...
Camera Settings: Av mode (2.8) Auto ISO (AF on * if it matters)
Flash:ETTL, HSS, Zoom --mm

Results:
w/o flash: 1/15 2.8 ISO 800
w/ flash: 1/15 2.8 ISO 400

I know I have some setting wrong only changed ISO and only by 1 stop, but can't figure it out.

 

[mtfd635]

The sensor size icon only shoes up u enable it in Custom Function
I don't remember which or how, but it's in the manual

 

[nateMN]

The sensor size icon only shoes up u enable it in Custom Function
I don't remember which or how, but it's in the manual

Found with more playing around that it appears when the flash is facing straight forward and not in an angled bounce position.

Still can't figure out how the flash will tell the camera to have a faster shutter speed on Av mode with the flash on (or if it can).

 

[Big Mike]

Found with more playing around that it appears when the flash is facing straight forward and not in an angled bounce position.

Of course. Recognizing the sensor size only matters when the flash is pointed forward, because that's the only time the camera & flash know the light spread in front of the camera. If the flash it tilted up, you are probably bouncing the light, which introduces more variables that the camera/flash can't know about. Don't worry about it.

Still can't figure out how the flash will tell the camera to have a faster shutter speed on Av mode with the flash on (or if it can).

For the most part...shutter speed has no bearing on flash exposure. All else being equal, you will get the same flash exposure at 1/15 as you will at 1/200.
The camera will act differently in different modes, when it comes to flash. In full auto, it defaults to a minimum shutter speed of 1/60 (I think) and probably the max aperture (depending on the light, of course). The flash then provides the light required for the exposure. The result is that you may end up with photos of people who look like they are in a dark cave.

If you switch to Av or Tv, the camera will give you aperture and shutter speed settings to expose for the ambient light (could be rather slow shutter speeds). The flash then adds what it needs to, to give the 'subject' enough light. This is sometimes gives better results than the full auto modes, but it can also cause other problems because of the slow shutter speeds.

What I do, when shooting with on-camera flash, is to put the camera into Manual mode...keeping the flash in E-TTL.
I adjust the aperture for the DOF I want (keeping in mind that a wider aperture requires less flash power). The flash will automatically adjust it's output to the aperture setting but you can use FEC to adjust the flash exposure.
I adjust the shutter speed for the ambient (background) exposure. A slower shutter speed will give you more ambient exposure. (dragging the shutter)
The flash can help to freeze the image of the subject...even with slower shutter speeds....but if there is enough ambient light, you still have to watch out for too slow of a shutter speed, because it can still cause blur.
Turning up the ISO can also give you more ambient exposure and requires less flash power.

If you really want to read all about it....here is the 'Canon Flash Bible' Flash Photography with Canon EOS Cameras - Part I.

 

[nateMN]

Thanks for you detailed reply Big Mike! I'll have to take a look at the link and get more educated.

If you switch to Av or Tv, the camera will give you aperture and shutter speed settings to expose for the ambient light (could be rather slow shutter speeds). The flash then adds what it needs to, to give the 'subject' enough light. This is sometimes gives better results than the full auto modes, but it can also cause other problems because of the slow shutter speeds.

I noticed this too in Av. I was hoping it would increase shutter speed because of the flash, but just lowered ISO.

What I do, when shooting with on-camera flash, is to put the camera into Manual mode...keeping the flash in E-TTL.
I adjust the aperture for the DOF I want (keeping in mind that a wider aperture requires less flash power). The flash will automatically adjust it's output to the aperture setting but you can use FEC to adjust the flash exposure.

I too switched to full manual to control Av and Tv settings. Unless I'm missing something, it looks like it will be a trial and error/correction with the flash in manual and adjusting the flash power to get the correct exposure.
(ie f/2.8 at 1/60, then "find" correct power - 1/32 or something) I was really hoping the "pre-flash" system would help with this and select the proper power while the camera is in Av or M.

 

[Big Mike]

Unless I'm missing something, it looks like it will be a trial and error/correction with the flash in manual and adjusting the flash power to get the correct exposure.
(ie f/2.8 at 1/60, then "find" correct power - 1/32 or something) I was really hoping the "pre-flash" system would help with this and select the proper power while the camera is in Av or M.

No, you can still use E-TTL (auto flash metering) with the camera in manual mode...and it should give you a relatively accurate flash exposure. The main advantage of this method is that you can use the shutter speed to control the ambient exposure, separately from the flash exposure.

You then use FEC to adjust or fine tune the flash exposure. Because you are using 'auto' metering, you will need to adjust the FEC differently for different subjects.