Basic questions about a slave flash

Joined: 16 Mar 2007 Posts: 69

I just purchased a Canon S3 and have been looking into accessories that I might want/need. I read about a slave flash, so went to my local camera store to find out more. I was rather disappointed with the response I got, which was- 'You can't use one of those with the S3, and why do you want one, anyway?' Okay, well, I was expecting him to tell *me* why I would want one, not the other way around.

I felt a little like I was taking a test. So- tell me how I did with my answers. I told him I want one because a bigger light source would be better quality light. And because having light from two angles would fill in shadows better. And, since its more powerful I could use it for objects that are further away which might be handy if I'm using the 12x zoom capabilities.

Why *do* I want one? They look cool, but I'm sure there's more to it than that.

Joined: 13 Jan 2007 Posts: 245 Location: Maryland

Quote:

So- tell me how I did with my answers. I told him I want one because a bigger light source would be better quality light. And because having light from two angles would fill in shadows better. And, since its more powerful I could use it for objects that are further away which might be handy if I'm using the 12x zoom capabilities.

You probably taught him something!

All valid reasons to own a slave flash. Larger though? Such a small amount larger, would really make nearly no difference at all.

So, why do you want one?
Honestly, if you can't answer that, you don't need one yet.
Perhaps your an equipment hound and just gotta buy it cause you got the bucks lying around collecting dust.

Or perhaps you want to improve your skills and master balancing flash and ambient light, flash fill, multiple light sources, improve the look of your images with off camera flash and the like.

Then you need one.

hth,
Jacque

Joined: 16 Mar 2007 Posts: 69

I wasn't certain if it would be enough larger to make a difference in that regard.

I'm always looking for more light when I do photo shoots with my girls. On the other hand I don't really have any complaints with my current set up, which is typically window light. Its very economical, but not always reliable since the right weather and time of day has to match up with an agreeable child.

Thanks

Posted: Fri Mar 23, 2007 1:28 pm

I don't know much about the S3, but if you go for a slave there are some caveats to think about

The flash metering on most digital cameras works by firing a pre-flash, metering that and then firing the main flash. This presents two possible problems when using a slave:

1. The slave fires on the first flash.

This will make the camera drastically overestimate the light available and underexpose the shot (it took me AGES to figure this out when I first tried a slave flash with a digi-compact).

2. The first flash is dim enough that the slave doesn't go off, but it fires on the main flash.

In this case the camera will have metered for it's internal flash only and you will get massive overexposure.

To operate successfully you either need to be able to set everything manually and have the camera just fire the flash once, or the slave needs to be specifically designed to work with your camera so that it fires on both the pre and main flashes and everything works as designed.

Joined: 13 Jan 2007 Posts: 245 Location: Maryland

Sammi,

I wanted to emphasize when you said:

Quote:

a bigger light source would be better quality light.

Sammi wrote:

I wasn't certain if it would be enough larger to make a difference in that regard.

Perfectly true. A slave flash would, if anything, be minimal difference in terms of quality of light and shadows from the on camera pop up flash. It's simply not really that much bigger, you know?

The bigger a light source the softer the light (and shadows) will be. Distance also effects this, sine the closer a light source is, the bigger it appears to be (which since it is larger close up than farther away = softer light right?)

Now balancing both flashes and/or ambient light can be done perfectly well of course, and eliminate the hard shadows from the small light sources.

Main reason to have a slave flash (well to me) in your situation would be to like you said:
-have an available light source anytime you want it.
-off camera lighting, to avoid flat lit images, and more creative control
-a bit of extra light when needed (again, like you said)

You should be able to use a slave flash of most any brand, in manual mode at least, provided you trigger it with the cameras pop up flash using a device like this. It simply mounts onto the flash's hotshoe, and detects your cameras flash. It will also work with cameras that have a preflash, only firing on the flash for the actual exposure. I've used these myself in the past.

Quote:

...I don't really have any complaints with my current set up, which is typically window light. Its very economical, but not always reliable since the right weather and time of day has to match up with an agreeable child.

I'm looking forward to seeing more of the window light images from you!

hope this helps,
Jacque