piyomaru Posted September 11, 2007 Share Posted September 11, 2007 Hi all, I am a newbie to DSLR and have a question regarding Canon's E-TTL. I just purchased an Rebel XTi and was given a 380EX flash unit by a friend. According to the Canon website's description of how E-TTL works with an external EX flash unit, there should be a preflash before the actual picture being taken. I would like to know if this preflash should be noticable by human eye because I don't notice any when I shoot using my XTi + 380EX. Thank you! Link to comment Share on other sites More sharing options...
rainer_t Posted September 11, 2007 Share Posted September 11, 2007 -- "I would like to know if this preflash should be noticable by human eye because I don't notice any when I shoot using my XTi + 380EX." You would only notice the preflash, if you sync the flash on the second curtain (and I'm not sure you can do that with the XTi 380ex combination). Link to comment Share on other sites More sharing options...
tommyinca Posted September 11, 2007 Share Posted September 11, 2007 You can't notice the gap between pre-flash and main flash. The pre-flash however is ahead of the main flash, so process then can be trigger by light source start with the pre-flash (slave flash, eye blinking and etc). If you want to check the preflash alone, use the FEC (ie: *) button in your camera before you press shutter release. 380EX support 2nd curtain sync so you can use that to check pre-flash too. Note: Dial in a slow shutter speed for your eye. Link to comment Share on other sites More sharing options...
joe chan Posted September 11, 2007 Share Posted September 11, 2007 You can see the pre-flash through the viewfinder prior to the shutter opening. For a long time, I thought this was very odd until I realised why. With older TTL flash systems without pre-flash, you wouldn't see the flash through the viewfinder because the mirror would be up and blank the view. Link to comment Share on other sites More sharing options...
pc1 Posted September 11, 2007 Share Posted September 11, 2007 I'm not really sure the 380EX supports preflash , i have one but never have expected it to do pre flash (modeling flash) , coz it's an old design (but then again i could be wrong) , i also have a 550EX that does modeling/pre flash. anyway, most of them knowlegeable photographers here might have the answer, sorry ! couldn't be of any help. PC Link to comment Share on other sites More sharing options...
joe chan Posted September 11, 2007 Share Posted September 11, 2007 According to my 380EX manual, preflash is a low output flash that is fired when the shutter is fully depressed but before the shutter is opened. It is to enable the camera to calculate the required flash output for the exposure. If the original poster is referring to modeling flash, then the 380EX doesn't support it (at least not when used on my EOS 1V). Link to comment Share on other sites More sharing options...
piyomaru Posted September 11, 2007 Author Share Posted September 11, 2007 Now, I am even more confused. What is this "modeling" flash? I've only heard of preflash for E-TTL combined with an EX series flash. In fact, I saw my friend using this 380EX on his Powershot G2 which also uses E-TTL and I can clearly notice a preflash before the main flash. That's why I am asking this question since I cannot see this preflash on my Xti. Link to comment Share on other sites More sharing options...
joe chan Posted September 11, 2007 Share Posted September 11, 2007 Some camera / flash combinations support a modeling flash feature where the flash fires a rapid burst for a couple seconds. This allows the photographer to quickly check the lighting effect and shadows. I don't know if the XTi has this feature but the EOS 1V works by pressing the depth of field preview button with the flash on. As I said above, it doesn't work with my 1V / 380EX combination. Perhaps what you're seeing on your friend's G2 is the red-eye removal feature where the flash fires a short burst before the main exposure. This is intended to cause the eyes' pupils to contract and so reduce the red-eye effect. Link to comment Share on other sites More sharing options...
colinsouthern Posted September 12, 2007 Share Posted September 12, 2007 Man, Easiest way to see a preflash is to close one eye - stick the other one up against the view-finder - and take a shot. Any flash you see through the view-finder is pre-flash. About the only time you won't get a pre-flash is if the flash unit is in manual mode - not sure if your unit supports this. Contrary to what some have mentioned, it IS possible to see a pre-flash - but you have to be looking for it - it's only barely distinguishable from the main flash. Link to comment Share on other sites More sharing options...
joe chan Posted September 12, 2007 Share Posted September 12, 2007 Another way to see the preflash is to set the camera to self-timer mode, with the flash switched on, and press the shutter button. You will see the preflash as soon as the shutter button is pressed and the timer starts. When the timer elapses and the shutter is released, then you will see the main flash. Link to comment Share on other sites More sharing options...
rvalois Posted October 2, 2007 Share Posted October 2, 2007 The 380EX DEFINITELY does pre-flash because it sets off my studio strobes. So now I always do a pre-flash, this sets off my strobes, I wait 3 seconds for recycle (from a full-power pop), I have 16 seconds FEL on the 380EX and voila, perfect exposure. All this until I get some wireless transmission. Ray Link to comment Share on other sites More sharing options...
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