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Old Nov 11, 2011, 3:31 PM   #1
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Default Speedlite Bounce Flash w/ camera manual mode

For the longest time I've used my bounce flash with the camera in auto mode and the flash in ETTL. Average results were obtained.

It's time to figure out how to use the camera in manual mode with the flash.

I've spent some time googling this and I've gotten all sort of things in my head. Setting the flash to manual seems like a lot of trial and error. I also see that keeping the flash in ETTL and then using camera manual, with a 2 stop underexposure (f2.8, 1/16, iso 200) is a good starting point. I just tested it and it looked like it works pretty well.

My question is: is this a really complicated thing to do? Does anyone know of a good starting point to teach myself how to use this bounce flash with the camera in manual mode? I have a decent understanding of manual mode in general but adding the flash has really complicated things.

John
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Old Nov 12, 2011, 7:27 AM   #2
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John - it's not too complicated when you leave the flash in ETTL. You have to understand what happens with flash this way. When you press the shutter, the flash actually let's out an initial burst of light just before the regular flash and picture is taken. The camera meters using that initial burst and uses the information to adjust flash output. So whether the flash points directly at the subject or bounces, the process for the camera/flash is the same.

BUT, you have to understand that the flash/camera are doing a metering computation just like the camera does for exposure. And, just like bright/dark subjects in the frame can skew the camera's metering without flash, so too they can be thrown off in the flash metering computation. So sometimes you need to intervene a bit and adjust the flash output. Canon has flash exposure compensation (FEC) which does the same thing to flash that normal exposure compensation does to camera exposure. After the reading is taken, it forces a positive or negative adjustment to the flash output. In general I often shoot with a negative FEC. Unlike camera exposure, if you have too much flash you can ruin highlights quickly.
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Old Nov 12, 2011, 12:40 PM   #3
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I must be missing something major here. I'm in ETTL and camera manual mode (Canon Rebel XSI). To me it seems like the camera doesn't know that a flash is connected. The flash lightning bolt is present so I know its recognizing it. However, the flash seems to fire the same, regardless of how I set the exposure.

Right now I'm inside in typical inside light. The camera could probably take pictures without a flash but they may be requiring a slow shutter. So I set the exposure correctly and then the flash overcompensates. It seems like I need to set the exposure 2 stops down or something to account for the flash, but it still seems like guess work.

I just wanted to be able to control the aperture a bit while using a flash, rather than having the camera pick for me in automatic. But it seems like the camera and flash work together in automatic but not in M.

I'm sure this will be an ah-ha or duh moment once I figure it out. Thanks!

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Old Nov 12, 2011, 1:37 PM   #4
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I think my problem here is that I really only understand the interaction of shutter speed, aperture value, and ISO. Adding a flash is making me scratch my head. Normally I can adjust the main 3 settings according to my already present light source, but the flash isn't there when I'm setting the exposure so I'm confused at how correct exposure can be set when the flash isn't firing during the initial shutter/aperture adjustments.
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Old Nov 12, 2011, 2:10 PM   #5
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If you need to choose the aperture, then using the Av mode would seem like a better way to go, as the camera will then be able to calculate the correct flash output.
Figuring direct flash based on guide number isn't too bad in manual, but indirect flash adds a variable which is difficult to work out without a flash meter, or a lot of trial and error.
When you use manual mode, the camera will not take into account the additional light provided by the flash, and you will end up with overexposure, which is what seems to be happening.

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Old Nov 12, 2011, 6:20 PM   #6
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Quote:
Originally Posted by VTphotog View Post
If you need to choose the aperture, then using the Av mode would seem like a better way to go, as the camera will then be able to calculate the correct flash output.
Figuring direct flash based on guide number isn't too bad in manual, but indirect flash adds a variable which is difficult to work out without a flash meter, or a lot of trial and error.
When you use manual mode, the camera will not take into account the additional light provided by the flash, and you will end up with overexposure, which is what seems to be happening.

brian
I think you nailed it. Av works well, but M is craziness. Ha. Thanks.
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Old Nov 13, 2011, 5:54 PM   #7
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M is not that bad. My old flash came with a calculator in the back.

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Old Nov 13, 2011, 10:58 PM   #8
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My Vivitar 285 Auto-thyristor works very well in these situations also, but it doesn't have any ttl capability. My ttl flash doesn't have a light sensor to be able to use it in auto mode with camera in manual, as it relies on the camera for sensing. Would be nice to have a single flash which could do both.
The calculators are really only going to work for direct flash, unless the flash has a light sensor to be able to control the exposure. John is working with bounce flash, which makes calculating manual exposure a real crap shoot, since the distance to the reflective surface, and its reflectivity are going to have to be factored in.

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Old Nov 14, 2011, 7:53 AM   #9
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Brian - actually, the camera DOES take into account the flash output in TTL - it's the pre-flash. The camera/flash emits a pre-flash and the camera uses that reading, through the lens, to adjust flash output. That's how TTL works.

I do 99% of my flash work with the camera in manual exposure. The problem occurs, usually, when the exposure you dial in on the camera is "correct" for ambient light levels. The secondary problem is, as I say - how the flash meters. If I use Flash exposure Lock (FEC) on a face, I've never gotten a bad flash output. You don't always have time to do that though.
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Old Nov 14, 2011, 11:10 AM   #10
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John - I am aware of how TTl (or P-ttl or E-ttl, whichever camera you use) works. (actually,true TTL has only been implemented on one DSLR that I know of, and that is the Pentax *ist D, all others are p-ttl, and need the pre-flash to calculate exposure) Are you telling me that it is going to adjust the flash output when the camera is in manual exposure as well? How do it know? Why would you want it to? If the exposure is correct for ambient light, why would the flash fire at all in that case?
I don't get a pre-flash when I set my camera to manual exposure, which lets me use slave flashes with it in this mode. Adjusting flash power, in this case has to be done manually, as well.

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