Flash question...

[gravity0]

What's the difference between a dedicated and a non-dedicated flash? It's not making sense as both look the same.

Thanks

 

[Big Mike]

A dedicated flash is designed to work with your camera, it communicates with the camera, usually for things like TTL (through the lens) metering.

For example, if you have a dedicated flash for your camera (a Canon 430EX on a Rebel XTi), you can use E-TTL mode....which causes the 430EX to fire a pre-flash, which is read by the camera. The camera then tells the flash how much power to use for the actual flash when the shutter opens. This all happens in a fraction of a second, just before the shot it taken. When you change the camera settings, the flash (and metering) automatically adjusts itself. In a nut shell, it's an automatic setting for your flash. There are other benefits, like HHS (high speed sync) and auto zooming of the flash head.

A non-dedicated flash, on the other hand. Only gets a message from the camera of when to fire. Some of these flashes have their own metering system, some just have a manual power adjustment. So this means that you have to understand a little better, how flash works and how to meter or adjust for it. If you change your camera settings, you have to change the flash settings to match, or you might end up with poor exposures.

Non dedicated flashes are cheaper and they are great for using as remote off-camera lights. But if you just want to stick a flash on top of your camera and not have to figure it all out...then a dedicated flash is the way to go.

 

[gravity0]

A dedicated flash is designed to work with your camera, it communicates with the camera, usually for things like TTL (through the lens) metering.

For example, if you have a dedicated flash for your camera (a Canon 430EX on a Rebel XTi), you can use E-TTL mode....which causes the 430EX to fire a pre-flash, which is read by the camera. The camera then tells the flash how much power to use for the actual flash when the shutter opens. This all happens in a fraction of a second, just before the shot it taken. When you change the camera settings, the flash (and metering) automatically adjusts itself. In a nut shell, it's an automatic setting for your flash. There are other benefits, like HHS (high speed sync) and auto zooming of the flash head.

A non-dedicated flash, on the other hand. Only gets a message from the camera of when to fire. Some of these flashes have their own metering system, some just have a manual power adjustment. So this means that you have to understand a little better, how flash works and how to meter or adjust for it. If you change your camera settings, you have to change the flash settings to match, or you might end up with poor exposures.

Non dedicated flashes are cheaper and they are great for using as remote off-camera lights. But if you just want to stick a flash on top of your camera and not have to figure it all out...then a dedicated flash is the way to go.

Thanks Mike, that Helps.

 

[Katier]

BUT using TTL is very much like using 'program' or a preset on your Camera.

Most professionals will be using in manual mode and off camera. This is so they can control exactly how much light falls and where on the subject.

 

[Joves]

Yeah I rarely use TTL as it is. Old habit from when cameras didnt have electronics.

 

[zbo2408]

Is there a best of both world options? I am a beginner with my XSi & there are times I would like to have an off camera flash ... but I could use the TTL option until I know how ot use it better.

 

[Big Mike]

Because of the communication required, it's a little more complicated if you want to use 'off camera TTL'. You can do it within the Canon system, but you need a master and a slave....so either one 580EX as a master and then either another 580 or a 430.

If you are leaning toward off camera flash, I'd suggest a cheap manual flash anyway.

A 'best of both worlds' is a dedicated flash, because you can also use it off camera, either with E-TTL (providing you have the rest of the system) or you could use it manually (provided you have some way to fire it).

BUT using TTL is very much like using 'program' or a preset on your Camera.

Most professionals will be using in manual mode and off camera. This is so they can control exactly how much light falls and where on the subject.

While TTL is like an auto mode for your flash metering...you can still have quite a bit of control while using it. For example, when I'm shooting with flash, I will usually have the camera in manual and the flash in E-TTL...but I'm quick to adjust the FEC when needed.

 

[Village Idiot]

BUT using TTL is very much like using 'program' or a preset on your Camera.

Most professionals will be using in manual mode and off camera. This is so they can control exactly how much light falls and where on the subject.

Not exactly. TTL is great for when you're in a dynamic environment and your subjects and subjects' distances are always changing.

Taking time to set camera setting in manual mode is easy, but having to back away from the camera and adjust the power on the flash or having to run over to a flash on a stand and adjust it to get the proper exposure is going to leave plenty of time for you to miss a good opportunity for a photo.

Each has their place in time. I wouldn't use TTL flashes when shooting models that are in a static environment where the only thing that's apt to move is the model's body and not their position on a set. If I was shooting a wedding, or some other event where things are constantly happening and I'm constantly moving around, then I wouldn't hesitate to use TTL mode on a flash.

There are many experienced and pro photographers that will share my views.