300D and flash

Printable View

  • 07-13-2004, 05:49 AM
    300D and flash
    I just bought a 550ex to go with my 300D and as far as i can tell the flash is zooming with the actual focal length of the lens not the effective focal length. has anyone encountered this before ? is there anything that can be done to overcome this, one of the reasons i bought a 550ex rather than my sunpak 4500 was it was suppossed to be integrated with the digital. i might not throw out the sunpak after all.
  • 07-20-2004, 01:14 AM
    There is no need for concern! This is correct. Your flash is functioning properly and will work correctly in conjunction with your camera.

    As far as the flash is concerned it is covering a 35mm frame size. The sensor in your camera is smaller than the 35mm frame - hence the 'effective' focal length you mention. If you think of the sensor as simply a 'crop' of the 35mm frame, you will see that the flash is, in fact, giving the correct coverage on your 300D camera.
  • 07-21-2004, 04:19 AM
    you misunderstand me. i am aware of the differences between 35mm film and the 300d's cmos sensor and how that alters the effective focal length of the lens. what i am getting at is that this flash zooms to provide a more efficient power output for a given focal length. i understand that the flash cannot tell that the camera is digital. what i am driving at is that at 55mm for example a 300d will have a field of view (and therefore require a flash angle coverage) of approximately 90mm. so whilst the 550ex's ettl metering system might be so accurate that i will not notice a difference in the flash exposure. i could potentially have used a less powerful flash if the head had zoomed from 50mm to 90mm. i am not saying this is a major problem, but rather noting that maybe this is something canon should look at fixing in a firmaware upgrade.
  • 09-16-2004, 11:05 AM
    300D/Rebel flash
    I have just bought a Sigma EF500 ST flash for my 300D/Rebel and found it to be extremly good. I does all I want and is about half the price as the Canon 550EX. If you want one with everything the 550EX has and more then look at the EF500 Super.