Digital light meter and flash photography question...?

Question

I use a Canon 20D with a Speedlite 430ex II (I'm still trying to learn how to use the flash). Also, I prefer to shoot in manual mode. The problem I'm finding is that when shooting in a dark area, the camera's light meter always reads that it's too dark (which is why I'm using the flash). How can I know that the image will be properly exposed without any sort of meter? Sorry if the answer is obvious, but it's the one thing that's keeping me from understanding how to correctly use my flash. Thanks in advance!

Answer 1

There are advantages in using Manual Mode for flash photography. Your flash can be used in TTL mode. TTL works by emitting a pre-flash, reading the resulting light reflecting off the subject and using that value to alter the duration of the flash thereby controlling the light. TTL is very good at 'fill in' flash, anything else can be a 'mind bending' exercise, there are some things a TTL finds very difficult to do, a totally black background 'floating head' shot for instance, like this one.



http://www.flickr.com/photos/chris-judge/4884255235/in/set-72157624708137816/



The advantages of using Manual everything with a flash shot is you can control the ambient and flash components independently. The problem is getting the exposure right. Digital has given us the opportunity of just 'chimping' it. Taking a shot and adjusting, take another and so on.



Manual flash works like this;



ISO and aperture effect both the ambient and the flash components.



Flash power and flash to subject distance effects just the flash component.



Shutter speed effects just the ambient component. The duration of the flash is so short (faster than 1/1000th of a second at full power to 1/50,000th of a second at 1/256th power is normal) that slower shutter speeds don't have any effect on the flash component.



You can take the guesswork out of this procedure with a flash meter. You trigger the flash with the meter from the subjects position pointing back at the camera, an incident light reading. This measures the light falling onto your subject and will always give an accurate exposure, accurate to 1/10th of a stop.



You set the meter with the ISO and shutter speed you will be using, fire the flash and the meter will give you the aperture including 1/10ths.



Note) The fastest shutter speed you can use with a DSLR with it's focal plane shutter is called the X speed and varies with manufacturer, anything from 1/160th to 1/250th of a second, it will be in the cameras spec. This is the fastest speed you can use when all the sensor is exposed, faster than this and some of the frame will have a darker band across it usually at the bottom of the frame, this is the part of the sensor that doesn't see the flash.



Chris

Answer 2

You have answers that are probably confusing you. Fhotoace is basically saying you don't have to worry about it, which is true. That is what TTL, (through the lens metering), is all about. Your in camera meter is meaningless with flash photography.



When using the camera in manual, all you have to do is be sure you are not setting a shutter speed over the max X sync speed, which I believe to be 1/200 with your camera, but you can use a max of 1/180 to be on the safe side. Check your owner's manual to see what your sync speed is. Then remember the larger the aperture, (the smaller the fstop number), the less hard your flash has to work. You would find it nearly impossible to get a correctly exposed shot with an aperture set in your camera of f11 or higher. Set your fstop to 5.6 or even lower. You can also set your shutter speed lower if you want more ambient light in the scene, but usually you don't want to go below 1/40. I like to set my ISO to 400, which again makes life much easier on the flash. The flash will read light reflected off the scene and cut off power when needed. If you are using some type of diffuser, you may have to put in some positive flash exposure compensation, sometimes not.



The above is when you are using the flash as your main light source. Things are very different if you want to use the flash as a FILL light, but that is another subject.



steve

Answer 3

The only thing that comes to mind is the ISO value - the higher the more sensitive to light. Problem with low light photography without flash are the long exposure times. Especially indoors. If no flash can be used a tripod (mini tripod) will be necessary otherwise the pics will be blurred.

Answer 4

Try Trick Photography Special Effects - http://tinyurl.com/n3OVrmUITN

Answer 5

1

Answer 6

In film photography using an electronic flash unit with an adjustable camera went like this...



Set asa on camera and flash unit.

Set shutter speed on camera that will synch with flash unit to make a full frame image in camera.

Look at subject, focus camera and read distance to subject.

Look at flash unit analog/slide type calculator for distance/f stop. Read f-stop. Set exact or set nearest f stop on camera lens.

Put camera to face, tell everybody to say "cheese" and snap shutter.



Some thoughts.

Using an original technology flash bulb type flash unit set camera on flash bulb (actual picture of flash bulb on camera shutter speed dial on early film cameras !!! You did not even have to know how to read.) Or set camera on 1/25 or 1/30 second to synch with flash bulb flash units.

On early film cameras, there was a lightening bolt picture on shutter speed dial to indicate shutter speed setting which synched with electronic flash unit.



Now this is where your whiz bang, super high tech, Buck Rogers camera comes in...Set camera for synch with electronic flash unit...or the camera does it for you !!! What will they think of next.? To understand digital camera to electronic flash synchronization, just read the manual. It will be some shutter speed or shutter speeds of like 1/125 second to like 1/3000 second.



The camera, flash unit or both may or may not set correct aperture for you. Again very Buck Rogerish. Answer is simple. Read manual.



To do yourself read manual to set camera on manual and flash on manual. Then read the first few lines above.

All you need is correct iso set on camera and flash.

Put camera and flash on manual setting.

Focus. Read distance on camera lens.

Find distance on flash calculator thingy. Read distance/aperture setting.

Turn/set aperture number on lens aperture ring thingy.

Tell everybody to say "cheese." Press shutter button to take pic.



And shucks. To answer your question about flash photography.

Focused light falls off the farther from light source.

So up close, you got more light and have to use a smaller f stop to get a proper exposure to make an image with the iso set on your camera.

Farther out, light level falls off, same iso setting, you need to open lens aperture to have enough light to make a properly exposed image.

There are limits, to close or to far. But in between, same power setting on flash, same iso setting on flash and camera, you should be able to set aperture to take a flash pic for every distance on the flash units built in manual calculator.