Manual calculation of fill flash

[mblanton]

How did photographers manually calculate fill flash before cameras became computerized? Could you please give me an example.

I was thinking of taking my cameras (10D) computer out of the equation, setting it to manual, disabling auto-reduction of fill flash, so I can control everything. I want to take an outdoor portrait of my family. We've got a really pretty tree that is currently changing colors, its in a semi-shaded location. I was thinking if I metered on my wife or daughters face, that should give me the ambient exposure that I'm looking for. Then I'd simply dial my flash (420EX) to -1. Would this work? I want the photo to have a really warm rich look, not flat and overcast. Can you reverse fill flash? Effectively using the flash as the main light and ambient light as the fill. Would this translate into setting the flash to +1?

Advice would be helpful here. Thanks everyone.

Mike

[jra]

The easiest (or most accurate) way would be to use a light meter and get an ambient reading and then balance that with your flash to get the effect you desire. As far as -1 and +1...are you talking about FEC?....If so, FEC would be of no concern if you're shooting in manual mode....and yes, you could use your flash as your main light source (meaning the brightest light source) as long as it's got enough "oomph" to over power the ambient light.

[Curtis N]

The 420EX has no manual option, so you're stuck with E-TTL and its quirks. It tends to work well outdoors, though.

Your 10D uses the original version of E-TTL with auto fill flash reduction, so I would leave the FEC at 0 to start, chimp and adjust from there.

"Main light" and "fill" are just terms we use. The camera really doesn't think that way. It calculates ambient exposure first and flash exposure second. To get the balance you want, adjust EC to expose the background and adjust FEC to expose the subject.

[mblanton]

If my camera is set to manual mode, 100 iso and I meter my subect @ 1/125, f/8 and set -1 FEC (with auto reduction of fill flash disabled), how is that TTL and not fully manual?

[Curtis N]

-1 FEC simply means you're telling the E-TTL system to expose one stop less than it would at 0 FEC. It's not manual flash.

[mblanton]

So, is there a surefire way to get the correct exposure without looking like you've never taken a photo before?

And if I understood correctly, the 420EX does not have constant power output. So it would do no good to use a flash meter with this unit? Would it not be easier to use a vivitar 283 or sunpak 383 (meter them at a given distance and shoot away). Of course they would have to be triggered via wireless or pc cord.

Mike

[Inspired Photography]

So, is there a surefire way to get the correct exposure without looking like you've never taken a photo before?

And if I understood correctly, the 420EX does not have constant power output. So it would do no good to use a flash meter with this unit? Would it not be easier to use a vivitar 283 or sunpak 383 (meter them at a given distance and shoot away). Of course they would have to be triggered via wireless or pc cord.

Mike

You are half right... the 420EX has a consistent power output, but not a 100% predictable one, as it does rely on the camera for output calculation.

A flash meter would help, you could adjust FEC based on your readings, but it wouldn't give the same results as adjusting flash output by a stop or whatever manually.

Using a Vivitar or Sunpak manually is a good option for what you want to do. The cheaper Speedlights are really designed to be a higher power version of your onboard flash, they are not really designed for much more. A 430EX or 550/580/580II etc all have manual control, so you get the best of both worlds - ETTL for on-the-fly, and manual when you need it.

Rob

[Wilt]

The purely manual process...
a. Using GN of flash, calculate the correct exposure for the given distance to the subject.
b. Now set the aperture to ONE smaller opening, e.g. f/5.6 is the 'correct' flash exposure for the distance, so you set f/8 on the lens.
c. Next meter ambient light and find a combination of f/stop and shutter speed which matches the set aperture...if the meter shows 1/50 f/16, then you set that on the camera.
The result is ambient light is perfect, and the fill flash provides illumination that results in -1EV exposure in those shadow areas.

Translating that into an ETTL flash...
1. Put the flash in Manual mode. Use the GN for the flash, proceeding with steps A thru C

[Curtis N]

So, is there a surefire way to get the correct exposure without looking like you've never taken a photo before?Not with a 420EX. But if you had a flash unit with a manual mode, you could either use the method Wilt described, or you could use a flash meter.A flash meter would help, you could adjust FEC based on your readings, but it wouldn't give the same results as adjusting flash output by a stop or whatever manually.With E-TTL, the flash meter would likely just read the pre-flash and give a useless measurement.

Mike, don't be afraid of E-TTL. Like I mentioned, it usually does a good job with outdoor fill. I took a bunch of outdoor family portraits a few weeks ago and used E-TTL (even though I had other options) and they turned out fine.

If you're really paranoid, you could manually bracket the flash exposure, adjusting FEC up and down +/- 2/3.

[mblanton]

So, I'm looking at two different setups:

1. (2) sunpak 383 flash, light stands, brackets, umbrellas, and a wireless trigger. I estimating this to be about $300 buying everything except the trigger from B & H. I'd get a trigger from ebay.

2. (1) canon speedlite 580 EX II. About $450 at wolf camera.

Seeing how unhappy I am with the 420EX I would have a hard time buying another canon flash. Is there anywhere I could rent this unit for a week to try it and see how it performs?

Mike

[Curtis N]

I don't know why you're unhappy with the 420EX. It's a consumer level unit, not designed for serious professional use except maybe as an E-TTL slave, but honestly it would fit the bill for 99% of the flash shots I take.

If all you want is manual control, the 430EX or a Sigma Super would work fine, too.

If you want a 580EX II, there are cheaper places than Wolf to buy one. Check the usual online retailers. But it wouldn't make much sense to buy one unless you really need some feature that's lacking in the units I just mentioned.

The sunpak 383 & umbrellas route will give you many creative possibilities if off-camera lighting is what you're really interested in.

[mblanton]

I've been reading everyone's responses and wanted to say thanks. I'll check back later (working now).

Mike

P.S. If you have pictures taken with the 580 EX II, or another setup that you just love, I'd love to see them. I'm trying to find a system that will work for me.

[roman_t]

get one softbox for portraits too! off camera 420ex with white translusent umbrella is for group shots.

[rhys]

For fill flash...
Set the camera to the flash sych speed (1/125 on most film cameras).
Set the aperture to match the scene.
Then set the flash to give out power equal to the given aperture at the given distance.

Sorry - probably as clear as mud to most people.

[da_teacher]

2. (1) canon speedlite 580 EX II. About $450 at wolf camera.



Why would you want to spend that money when you can order online and save yourself a hundred bucks? People actually buy from Wolf?

[Sele]

For fill flash...
Set the camera to the flash sych speed (1/125 on most film cameras).
Set the aperture to match the scene.
Then set the flash to give out power equal to the given aperture at the given distance.

Sorry - probably as clear as mud to most people.

Sorry to interrupt this thread, I got this part, but my question now is do you make any adjustments to the manual settings on the flash when you bounce the flash off of an umbrella. Do you have to make up for the diffused light?

[Curtis N]

An umbrella will most certainly reduce the output and require either a larger aperture, or more flash power, or both. The flash unit's guide number is fairly useless for any sort of calculation.

But if you're using a meter, you adjust those things until you get the meter reading you want, regardless of light modifiers.

[rhys]

Sorry to interrupt this thread, I got this part, but my question now is do you make any adjustments to the manual settings on the flash when you bounce the flash off of an umbrella. Do you have to make up for the diffused light?

Umm... With a thyristor controlled flash, as long as the sensor is aimed at the subject nothing much should change other than you'll have to use the lighter flash options and expect it to use more of its power on the bounce.