Okay, I've never really used flash much, and what I know about it is this: You push the button that pops up your flash, and you take the picture....
Seriously, I've been shooting for awhile (mostly landscape stuff not needing flash), but I'm beginning to run into some situations where it might be beneficial (such as keeping the shutter speed up on shots at dusk). I've read the "Lighting 101" stuff on the Strobist website - the strong recommendation there is to avoid ETTL and get a manual flash. But I think most of the uses I'd have for flash would more often be on-camera rather than off, and if the camera gives you flash exposure compensation control over external flashes, won't that basically do the same thing that a manual power flash can? One big hesitation in getting a manual is that all I've found are fairly bulky and heavy, and there seem to be some ETTL flashes (like Canon 270ex) that are tiny but probably powerful enough for my purposes. But due to my ignorance on this topic I don't really know what I may be missing here.........
Any advice appreciated.
What are you planning on taking pictures of with a flash?
That will help give a useful reply.
It has to be said there are very few times when an on-camera ettl flash will make a picture look better than having the flash off camera.
If you like the confidence of the ettl system pick up an ettl cord. I work with a corded ettl flash, often in a small ring light. It works beautifully.
I also use manual flashes on radio triggers as a cheap option to a studio, also with very good results.
I would suggest you get something like a 430EX that will give you the option of going to manual settings if you want to.
The usual times when I wish I had flash are when shooting around dusk and encountering "slightly" moving subjects that need faster shutter speed (such as my dogs when standing not quite still) or flowers, etc that are slightly disturbed by wind. This would be in a walk-around situation most of the time, hence the need for on-camera flash. Would a flash bracket move the flash adequately "off-camera"?
Stobist has an anti TTL bias because Mr. Hobby is frugal and only used cheap manual flashes. More recently he has tried ETTL with and discovered it works and is warming to the idea of using it. If you buy an external Canon flash it can operate in either ETTL or Manual mode as your shooting needs dictate. In general manual works best if the flash and subject are at a consistent distance, such as in portraiture. ETTL is a better choice if you or your subjects are moving around because the camera will adjust exposure automatically.
The basic things to realize about flash are:
1) The intensity decreases about 2 f/stops every time the distance doubles
2) Exposure is only correct at one distance from the flash.
In ETTL mode what your camera does when the shutter is pressed fully is: 1) meter the ambient light, then 2) fire a pre-flash and meter it. The metering is done off the viewfinder of the camera, not the sensor which is still hidden behind the mirror and shutter at that point. The ambient and pre-flash reflections are compared and then the camera makes an educated guess HOW FAR AWAY the most important stuff in the photo is and sets flash power to make the exposure correct at that distance.
The result of the camera's guess will:
A) put the point of correct exposure at the correct distance
B) Put it nearer or further away than you want
The odds of it being "A" are about the same as coin toss.
The camera can only guess what you want correctly exposed based on how you frame the shot in the viewfinder. If you put the back of Uncle Louie's white shirt in the foreground and Aunt Sophie's face 5ft further back the camera will think you want the shirt exposed correctly, not the face. So when composing a flash shot keep what you want correctly exposed nearest the flash.
If the camera doesn't put the point of correct exposure where you need it in the scene, we can override the camera meter with an FEC adjustment. The FEC adjustment is indicated in f/stops from -2 to +2 but actually what FEC does, functionally is change flash duration (which how power is modulated) and move the point of correct exposure closer (minus FEC) or further away (plus FEC).
Accept that exposure is never going to be completely automatic because the camera can't read your mind. Its very much like sighting in a new gun. Fire a shot, see where it lands, then correct the aim of the next shot with FEC.
An easy way to know what is correctly exposed is to turn on the camera's overexposure warning (OEW) which blacks out the over exposed places. Take a shot at FEC =0, look at the OEW and see where things like white shirts are blacking out, then adjust FEC until what you want correctly exposed is below where warning appears.
That is the basics... For more detailed tutorials click the WWW button below.
cgardner wrote:
...the camera makes an educated guess HOW FAR AWAY the most important stuff in the photo is and sets flash power to make the exposure correct at that distance. ...
I would add that with newer cameras and with ring-USM lenses, the lens communicates the focus distance to the camera, and the flash exposure is based on that distance since presumably your subject is what's being focused on.
BrianO wrote:
I would add that with newer cameras and with ring-USM lenses, the lens communicates the focus distance to the camera, and the flash exposure is based on that distance since presumably your subject is what's being focused on.
Good point. I tend to forget that because it only works with direct flash and I bounce flash up into diffusers most of the time...
