Help with 430EX needed

[munchy]

Hi Everyone,

I have just purchased a 430EX (on a 300D) and am a little confused...

When I take a shot, say in Av or Tv mode, the aperture/shutter speed seems unaffected by the speedlite (as if it wasn't there). The flash fires and I get what seems to be a perfectly exposed picture - but I'm sure I am missing something!

For example, I was taking pictures last night, fairly dark room, meter was reading something like f/4 0.5secs. I was expecting to put the flash unit on and see a change in the readings to say f/4 1/500 depending on the output of the flashunit but the readings stay the same. What I want is a high shutter speed to take out motion blur (which is why I bought the flash in the first place, to increase shutter speeds indoors!)

In order to get a high shutter speed I have to go manual (and set high speed sync) then the exposure warning seems to think that the picture will be waaaay underexposed, but when I take the shot, the flash seems to know how much light is needed and fills in to give a well exposed shot.

My flash 'workflow' seems to need a bit of looking at! I seem to be getting good results but not knowing how I got them...

Any help would be very much appreciated...

Munchy

[tim]

Read this (http://photonotes.org/articles/eos-flash/), from the FAQ. It doesn't know the 430EX is there, you have to know how to control it. Shoot in M mode, and learn about high speed/f p sync mode, all in that link and your manual. ETTL does know about how much light to put out to get a good exposure. Read that link and all will become clear. Flash is hard, btw, if you hadn't worked that out yet ;)

[René Damkot]

If the camera is in Av (or Tv) it will assume the flash is used as fill. Therefore using a shuttertime/aperture to get a good background illumination. If you don't want that, use either P, M or 'green rectangle'
By the way, you cant use 1/500 with flash, other then FP flash, and that won't freeze motion.
By the way also, if the meter reads, say 1/2 second @ f/4 without flash, and you use 1/8 or 1/15 @ f/4 with flash, the flash will properly expose & freeze your subject (because the ambient light on the subject is too underexposed to cause much blur), while the background will still be somewhat illuminated (say; lights in the Xmas tree). With 1/250s the lights in the tree and candles will look like they're off....

[munchy]

Cheers for the replies, the FAQ does answer most of my questions. I think things just work a little differently than I was expecting, I will have to have a play and see what works and what doesn't.

By the way also, if the meter reads, say 1/2 second @ f/4 without flash, and you use 1/8 or 1/15 @ f/4 with flash, the flash will properly expose & freeze your subject (because the ambient light on the subject is too underexposed to cause much blur), while the background will still be somewhat illuminated (say; lights in the Xmas tree). With 1/250s the lights in the tree and candles will look like they're off....

I would have thought that in a reasonably well lit room you would notice some blur from the ambient light, but, maybe not... I will have to investigate some of the Exif data from the portraiture section and find out what settings people are using.

By the way, you cant use 1/500 with flash, other then FP flash, and that won't freeze motion.

Why would this not freeze motion? Surely you can either use high speed sync (fast shutter and as I understand it have a shorter shooting distance) or if the scene is sufficiently dark, the short flash pulse will freeze the motion even if you have a slow shutter speed. Do I have this wrong?

Flash is hard, btw, if you hadn't worked that out yet

Photography is hard! But fun nonetheless.

Cheers, Munchy

[PacAce]

Why would this not freeze motion? Surely you can either use high speed sync (fast shutter and as I understand it have a shorter shooting distance) or if the scene is sufficiently dark, the short flash pulse will freeze the motion even if you have a slow shutter speed. Do I have this wrong?
Cheers, Munchy
The fact is, 1/500 will freeze normal people motion unless they are really moving fast. And this would be true whether you shot using ambient lighting or flash lighting. If the only significant lighting is coming from the flash, then it definitely will freeze motion. However, with flash in highspeed sync mode, what you might see is what looks like a double or triple exposure of people frozen at different positions of motion. This is due to the flash going off two or three times within the duration of the shutter being open.

[munchy]

Ahhh - gotcha. Cheers PacAce.

[René Damkot]

The fact is, 1/500 will freeze normal people motion unless they are really moving fast.
True. It won't stop fast motion though (falling things, cars etc)
Nice test here (http://webs.lanset.com/rcochran/flash/hss.html)

[PacAce]

True. It won't stop fast motion though (falling things, cars etc)
Nice test here (http://webs.lanset.com/rcochran/flash/hss.html)
As I said in my previous post, if ambient lighting does not enter into the picture, the flash will stop action, even at 1/500 with the flash in fp mode, just like it does with the shutter at or below max sync. However, what will be different is that you will get 2 or 3 exposures of the fast moving subject in the same frame but each exposure will be of the subject that has been frozen. Now, we're not talking about a flying bullet here, just common ordinary stuff, even a moving car. :)

BTW, in that link you pointed to, the author incorrectly stated that shooting in highspeed sync mode slows down the flash. It really doesn't. It only makes the flash fire multiple time within a given frame. The flash duration, of course, will be depending on the intensity of the flash, just like it is even when using the flash in normal non-fp mode. If anything, for the same flash exposure, putting the flash in fp mode will, in fact, shorten the duration of each flash pulse compared to the flash fired in normal mode.

[René Damkot]

Yeah, but the flash flashes at something like 50kHz AFAIK, so esentially it becomes a 'continuous' lightsource. I'ld say in a way both you and the author are correct....
I think in order to get just 2 or 3 'exposures' in the frame, the subject needs to move pretty damn fast ;)
Then again, I agree most 'normal' action will be stopped anyway by the shuttertime of 1/500s, but if the shuttertime wouldn't have stopped the action, neither will the FP flash, you'ld just get a kind of 'stroboscopic effect' with 100 exposures of the subject in 1 frame.
Then again, I also agree not many of us will come across a situation like that on a daily basis ;)

[PacAce]

Yeah, but the flash flashes at something like 50kHz AFAIK, so esentially it becomes a 'continuous' lightsource. I'ld say in a way both you and the author are correct....
I think in order to get just 2 or 3 'exposures' in the frame, the subject needs to move pretty damn fast ;)
Then again, I agree most 'normal' action will be stopped anyway by the shuttertime of 1/500s, but if the shuttertime wouldn't have stopped the action, neither will the FP flash, you'ld just get a kind of 'stroboscopic effect' with 100 exposures of the subject in 1 frame.
Then again, I also agree not many of us will come across a situation like that on a daily basis ;)
Rene, we were only talking about the shutter speed of 1/500. At that speed, on a camera with a sync of 1/250, you only get 2 strobes of the flash. On the 300D, you might get 3 tops. Or, at least that's my thinking. Now that you got me thinking, I'll have to go home and verify that. :confused:

:)

[René Damkot]

Hahaha, I'm curious as well. Never understood how they managed to eliminate the effect of the flash 'turning on and off' AFAIK the flash 'pulse' isn't a clean spike, but it 'fades out'. Anyone have a link to technical description? :D
(didn't mean to hijack this topic BTW, maybe start a new topic?)

[PacAce]

Hahaha, I'm curious as well. Never understood how they managed to eliminate the effect of the flash 'turning on and off' AFAIK the flash 'pulse' isn't a clean spike, but it 'fades out'. Anyone have a link to technical description? :D
(didn't mean to hijack this topic BTW, maybe start a new topic?)
Well, Rene, it looks like you were right after all and I stand corrected. The question you were asking re the "turning on and off" of the flash without leaving a trace on the picture has nagged me for quite a while, too. And I just found the answer to that question here:

http://www.chem.helsinki.fi/~toomas/photo/flash-discharge/hispeed.html

Thanks for the enlightening exchange of posts. :)

[munchy]

Hahaha, I'm curious as well. Never understood how they managed to eliminate the effect of the flash 'turning on and off' AFAIK the flash 'pulse' isn't a clean spike, but it 'fades out'. Anyone have a link to technical description? :D
(didn't mean to hijack this topic BTW, maybe start a new topic?)

Hijack away dude - this stuff is always interesting. Cheers for all the input.

Munchy

[René Damkot]

PacAce: Interesting reading! Seems the flash actually is on all the while...

[PacAce]

PacAce: Interesting reading! Seems the flash actually is on all the while...
It sure is. And that answers our question about why there isn't any evidence of the flash going on and off as the shutter shoots across the frame. :)