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Canon 580EX FEL question

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Stevil

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Is there any way to save a FEL setting with the 580EX, or does it automatically reset every time you take a shot? For example, if I set FEL off of a white wall and dial in 2 1/3 stops FEC, can I keep that flash power setting for all my subsequent shots?
 
No, but FEL isn't the best strategy.

All TTL exposures are a process of camera guesses / we second guess. Its when we try to out guess the camera's metering in advance of letting it do its thing that things fall off the tracks.

A Digic II/ E-TTLII camera with 35 zone evaluative metering does a pretty good job of sorting things out once a base level of FEC is established. E-TTLII compares pre-flash with ambient across the 35 zones just before the shutter opens so even focus/recompose works OK (not the case with earlier Digic/E-TTL bodies).

With my 20D I shoot in evaluative, compose normally, take a test shot, evaluate, then adjust FEC as needed.

CG
 
I was hoping I could find a more consistent method of getting the flash exposure right- sort of the white towel method for flash. The metering in my 300D is too inconsistent- I can shift the lens just slightly and get totally different results, even though 90% of the scene is the same as before. I get decent results by metering off my whitish walls and dialing in +2 FEC, but that still underexposes a bit with my 420EX. I was hoping that a 580EX would help the situation...maybe having +3 EC will help.
Chuck Gardner said:
No, but FEL isn't the best strategy.

All TTL exposures are a process of camera guesses / we second
guess. Its when we try to out guess the camera's metering in
advance of letting it do its thing that things fall off the tracks.

A Digic II/ E-TTLII camera with 35 zone evaluative metering does a
pretty good job of sorting things out once a base level of FEC is
established. E-TTLII compares pre-flash with ambient across the 35
zones just before the shutter opens so even focus/recompose works
OK (not the case with earlier Digic/E-TTL bodies).

With my 20D I shoot in evaluative, compose normally, take a test
shot, evaluate, then adjust FEC as needed.

CG
Click to expand...
 
Stevil said:
I was hoping I could find a more consistent method of getting the
flash exposure right- sort of the white towel method for flash. The
metering in my 300D is too inconsistent- I can shift the lens just
slightly and get totally different results, even though 90% of the
scene is the same as before. I get decent results by metering off
my whitish walls and dialing in +2 FEC, but that still underexposes
a bit with my 420EX. I was hoping that a 580EX would help the
situation...maybe having +3 EC will help.
Click to expand...
I don't see how your method would work. I assume you metered the flash power using the wall, then use that flash setting for human subject inside the room. The problem is that the distance from your camera to the wall isn't always the same as the distance from your camera to the human subject. Not to mention that human does move. Flash exposure changes significantly when the distance changes (inverse square law). So you probably never get the right exposure that way.

If your subject stands still, then use manual flash power. Just take a test shot, and dial in more or less power until it looks correct.

If your subject moves around, then you can either use ETTL or the old Thyristor Auto mode (not on Canon flashes). The Auto mode is more consistent, but then it doesn't take into account the different focal lengths. ETTL is a gamble, but I think it's good enough for 95% of the time.
 
Stevil said:
I was hoping I could find a more consistent method of getting the
flash exposure right- sort of the white towel method for flash.
Click to expand...
Actually the white towel method works perfectly for flash. In fact its how I calibrate my L-358 flash mete
Stevil said:
The
metering in my 300D is too inconsistent- I can shift the lens just
slightly and get totally different results, even though 90% of the
scene is the same as before.
Click to expand...
Well sadly we get what we pay for and the metering in the 300D is not as good as other later and more expensive Canon bodies. You might consider upgrading to a 400D with uses the same Digic II / E-TLL II 35-zone exposure system as the 20D, 30D, and 5D
Stevil said:
I get decent results by metering off
my whitish walls and dialing in +2 FEC, but that still underexposes
a bit with my 420EX. I was hoping that a 580EX would help the
situation...maybe having +3 EC will help.
Click to expand...
A 580ex will not help much because the problem is how the camera is evaluating the scene.

Also distance is a critical factor for flash and if the wall you measure isn't the same distance from the camera flash as subject the flash exposure will not be correct or consistent.

Try the broadest metering mode your camera has (center weighted) which will tend to average out the minor differences in spot-to-spot illumination which are affecting your exposure.

When using FEL try pointing it at the thing in the scene you want correctly exposed -- not a wall somewhere else - then adjust your FEC from that baseline. Use the white towel near that spot to gauge the exposure.

Remember the flash intensity will fall off 2-stops each time the distance to the flash is increased. So when framing your shots avoid anything in the shot which is closer than what you want correctly exposed. Ideally everything you wish to be correctly exposed should be the same distance from the flash. Nearer objects will either wind up overexposed or conversely fool the metering and result in your main subject further away being underexposed. I suspect that my be part of your problem; not realizing the flash photos need to be composed differently than ambient shots.

For example, a simple trick for evenly exposed large groups is to arrange them in arc a string tied to the flash head proscribes. Equal distance = equal lighting.

CG
 
Have a look at Don Cohen's technique over on Open Photo Forums where he utilized PF (not CF) 23 to hold your FEL setting for as long as you like, higher battery drain notwithstanding:

--
John Kirby
 
Stevil said:
...The metering in my 300D is too inconsistent- I can shift the lens just
slightly and get totally different results, even though 90% of the
scene is the same as before.
Click to expand...
Try an auto-sensor flash such as a Sunpak PZ5000 AF:

http://www.bhphotovideo.com/bnh/controller/home?O=647&A=details&Q=&sku=177009&is=REG&addedTroughType=categoryNavigation

It'll give more consistent results when making slight adjustments to camera position as opposed to E-TTL (300D).

Fairly regularly available on ebay from $40-$80 (avg.)

I have one I use on my 300D:

AUTO across a variety of apertures (but I have to set the aperture - mis-matching flash/camera aperture acts as a form of flash exposure compensation),

reads camera ISO and

lens zoom position (does not take into account crop factor, but then neither does a 420EX I believe).

Flash also has manual mode with 1/1 to 1/64 power adjustment.

--
Good Day,
Roonal

'Money doesn't buy happiness, but it makes for an extravagant depression' by golf tournament sportscaster
 
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