430EX, manual mode.... confused.

[Davan]

I just picked up a 430EX speedlite. Playing around with it, doing a lot of reading, trying to figure it out.

I composed a scene in manual mode 1/60th and f/1.8 My lightmeter told me the scene was properly exposed for ambient light. So the flash operates in fill flash mode, right?

I then composed the same scene, but closed the lens up to f5.6. Obviously my lightmeter is reading underexposed. I took the shot anyways. It turned out almost identical to the first shot. I assume the flash boosted it's output to compensate? Is the flash now operating as the dominate light source?

Then just for kicks, I closed all the way up to f/11. Still got a perfect exposure, even though the lightmeter was reading underexposed. Then went to f/18 and the result was an underexposed shot.

What is really confusing me, is I'm not seeing any type of feedback telling me that the flash can or cannot compensate for the underexposure. So how do I know if the shot will turn out okay, or not?

TIA! :)

[snibbetsj]

Yes the 430 will up the light output to get a good exposure on the main subject until it runs out of power. That the auto (flash) mode we lovingly call ETTL. Knowing the Guide Number, f-stop, ISO, and distance to your subject will tell you if the flash will have sufficient power to produce a good exposure. There should be a table in the back of your manual with this info in it.

[Davan]

I see the table in the manual. But it doesn't take shutter speed or aperture size into account.

So... I should go ahead and assume there is no way, just by looking at the info in the viewfinder and on the LCD, that I can know whether or not the flash has enough power to properly expose in the conditions I described above?

append - I'm not dealing with light fall-off here. Rather, a shutter too fast, or an aperture too small, to allow sufficient flash illumination to expose the shot.

[tim]

Read about ETTL here (http://photonotes.org/articles/eos-flash/).

[Davan]

I've printed that article off, read it, re-read it, and read it again. Still not finding an answer to one question... is there any form of feedback on the camera, or on the flash, that tells me whether or not in manual mode if i've picked a shutter too fast or an aperture too small, to expose my scene properly...

I'm assuming a downside to ETTL is there is no way to know this, until the flash has actually fired......?

[tim]

That's right, there's no indication about if the flash will be powerful enough until you take the shot. The only time that should happen is if you're in bright sunlight, a long way from your subject, or you've diffused too much. Just watch your histogram.

[Davan]

I guess that is our Digital Camera advantage. :)

Thanks again!

[PacAce]

With all the EX flashes that I have (and that includes the 420EX), you can fire a preflash using FEL and that will tell you if the flash exposure will be OK or not. So I would imagine the 430EX would work the same way. Just press the FEL button and see if the lighting bolt in the viewfinder blinks or not. If it does, the flash image will be underexposed. If it does not, then your setting (aperture) is fine.

[tim]

With all the EX flashes that I have (and that includes the 420EX), you can fire a preflash using FEL and that will tell you if the flash exposure will be OK or not. So I would imagine the 430EX would work the same way. Just press the FEL button and see if the lighting bolt in the viewfinder blinks or not. If it does, the flash image will be underexposed. If it does not, then your setting (aperture) is fine.

Heh, you learn something new every day! :)

[mbze430]

Tell me something I don't know.

[tim]

Tell me something I don't know.

Ducks sometimes sleep standing on one leg. I have pushed over sleeping ducks to test this unlikely sounding statement out.