add on flash

[gbrehmer]

Please bear with me, this is my first post, I hope I've picked the right forum. Would an add on flash for my Canon sx20is eliminate the streaking ghosts I get when is use the camera flash on moving subjects? Or can I compensate with the camera settings to eliminate this effect?

[prabbit237]

You probably just need to drop the shutter speed down. If using a flash, you can probably use a shutter speed of 1/500 or even faster. But just be aware of the fact that if you make it that short, then it picks up pretty much no light other than the flash. So the background might be completely black.

You're probably getting the extremely short exposure of the flash and that makes the subject plenty bright but then you're leaving the shutter open longer than needed and thus getting ambient lighting on the subject as well and thus the "ghosting" as the subject moves. With my camera, it doesn't adjust the shutter to a shorter time with an external flash and thus if I use AV or TV mode, it does that. I use manual settings and it's fine.

[gbrehmer]

I went back to my pictures and found out I had shot them in "landscape" and the settings were all wrong for what I was trying to do. I thought I had shot them in Manual with a 1/125 shutter speed. Next time I will try it in Manual like I thought I had done and see what happens. With this Canon the flash settings are 1st light curtain and 2nd light curtain, so the flash fires when the shutter opens or before it closes, and according to the manual will cause the ghosting. I'll play with it and see what works best. Thanks for the help.

[luminescent]

Originally Posted by gbrehmer

Please bear with me, this is my first post, I hope I've picked the right forum. Would an add on flash for my Canon sx20is eliminate the streaking ghosts I get when is use the camera flash on moving subjects? Or can I compensate with the camera settings to eliminate this effect?

What you are experiencing is an effect that photographers use as a creative effect, called "dragging the shutter." This happens when your shutter speed is low/slow and, if your camera settings are optimal, allows ambient light in your scene to be captured while the flash freezes your subject and/or provides fill light.

You can decrease the shutter drag (blur) effect by either increasing your shutter speed or opening up your aperture more (lower aperture value). However, less ambient light will be recorded and your background wll be darker and objects in the foreground will be lit by your flash.

[prabbit237]

Originally Posted by gbrehmer

I went back to my pictures and found out I had shot them in "landscape" and the settings were all wrong for what I was trying to do. I thought I had shot them in Manual with a 1/125 shutter speed. Next time I will try it in Manual like I thought I had done and see what happens. With this Canon the flash settings are 1st light curtain and 2nd light curtain, so the flash fires when the shutter opens or before it closes, and according to the manual will cause the ghosting. I'll play with it and see what works best. Thanks for the help.

Let me say that I'm, by NO means, an expert (I should have noted that earlier as well.) But basically landscape mode simply means the picture is wider than it is tall (portrait is taller than wide.) The "1st light curtain" and "2nd light curtain" shouldn't cause ghosting if the shutter speed is short enough. Basically, they affect moving targets. Think of doing a long-time exposure (1/2 sec or more) of a car at night. If you use "1st light curtain" then the flash fires in the first 1/1000th of a second or so and makes the car bright. But then the car continues to move and you see a "ghost" of it past the bright image due to ambient light and the headlights. "2nd light curtain" opens the shutter and picks up that ghost and then fires the flash right at the end so you see the ghost behind the bright image. If nothing is moving or if the shutter speed is short enough, you don't get any ghost at all no matter how long the shutter speed (but the longer the shutter, the brighter background objects become.) I think, in this case, the shutter speed might have been longer than you thought it was.

Maybe if you can post one of the pics and get the EXIF info, we can tell more about what might have caused what yer seeing.