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03-09-2010, 08:47 PM   #1
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beginner flash photography question

I am relatively new at photography and VERY new at flash photography. I recently purchased a Metz 58 af-1 for my k20d. I've only had it for a couple days and am making my way through the manual as well as experimenting with the flash. So far, I haven't ventured much out of PTTL, but I've had pretty decent results with the indoor shots with flash that I've bounced off of walls.

I am in the habit of shooting in Av mode on my camera, occasionally switching to manual. I noticed that when I am in Av mode on my camera and PTTL mode on my flash, no matter what f stop I choose, the shutter speed stays at a constant 1/60. Is that what is supposed to happen? I know - silly question - I am just making sure because it seems strange to me that the shutter speed would remain constant.

????

03-09-2010, 08:52 PM   #2
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When dealing with flash, shutter speed only has an effect on the ambient light, not the light from the flash (which fires way faster than even your max shutter speed). Yes it is normal for the shutter speed to stay the same. If you were to actually put the camera into Flash-Sync mode (the red X), it would remain at 1/180.
03-09-2010, 11:07 PM   #3
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in Av mode with the flash enabled, shutter speed is dictated by the focal length of the lens being used. If you're using the kit lens, try zooming all the way in or out, and you'll notice the shutter speed probably changes accordingly. It's perfecly normal, and the expected behaviour. The camera changes the exposure by making the flash brighter or dimmer, depending on the needs. With the built-in flash, the limit is reached by about 9 to 15 feet of distance. After that, your subject gets progressively darker. But with a Metz 58, the limit won't be reached until at least 100 feet, depending on the focal length of your zoom.
03-10-2010, 12:55 PM   #4
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Thank you! Makes sense to me now.

It's so funny....over this last year of owning my first dslr camera, I've been learning about aperture, shutter speed, focal distance, and ISO and how they all affect each other. I feel like I have a decent grasp of all of that. Now this flash thing is rocking my world and adds a whole new can of worms to the equation.

03-10-2010, 01:00 PM   #5
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QuoteOriginally posted by kewpie-o Quote
It's so funny....over this last year of owning my first dslr camera, I've been learning about aperture, shutter speed, focal distance, and ISO and how they all affect each other. I feel like I have a decent grasp of all of that. Now this flash thing is rocking my world and adds a whole new can of worms to the equation.
I know how you feel, and that's exactly how you should see it. Flash photography is a whole 'nother world with its own set of rules. When it comes to flash photography, flash intensity, distance from subject and aperture have more effect on exposure than anything else. Just wait till you start combining flash photography with ambient lighting... then you have to start keeping track of EVERYTHING!
03-10-2010, 02:15 PM   #6
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Yes! I thought my brain was going to explode yesterday when I was reading about and experimenting with outdoor fill flash.

So, am I understanding the basic idea correctly?.....A good place to start when balancing ambient w/ flash is to meter for ambient and then stop down the aperture a couple steps (so that if I just shot w/ ambient light, it would be fairly underexposed).....then.....hmmmm.....this is where I get confused.....Then, what do I do w/ my flash?

03-10-2010, 02:38 PM   #7
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Fill flash is typically used when your subject is going to be dark compared to the rest of the scene. For example, a portrait in front of a sunset. In this case, you want to meter for the background, and use the flash to light up the subject at the end of the exposure. This is where "Trailing Curtain Sync" comes in. In such a case, you want the aperture and shutter speed to be whetever you need to capture the background properly (keeping depth of field in mind), and you want to make sure the flash isn't too bright or it will make your subjects look like cardboard cutouts on a beautiful background. It's also best if the flash will not light up the background at all, that way you get no obtrusive shadows or weird gradients in your ambient light.

I'm no expert on fill flash, though. I'm also no expert on flash photography. I always try to shoot without the flash whenever possible. Having a good DSLR with a fast lens makes that possible most of the time.
03-11-2010, 09:13 AM   #8
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QuoteOriginally posted by kewpie-o Quote
Yes! I thought my brain was going to explode yesterday when I was reading about and experimenting with outdoor fill flash.

So, am I understanding the basic idea correctly?.....A good place to start when balancing ambient w/ flash is to meter for ambient and then stop down the aperture a couple steps (so that if I just shot w/ ambient light, it would be fairly underexposed).....then.....hmmmm.....this is where I get confused.....Then, what do I do w/ my flash?

Not exactly. I use mostly off camera flash with radio triggers. I am a novice for sure but here is what I have learned. It is said that you can cut the ambient and then use the flash to build up your subject. What you do is decrease or shorten the *shutter speed* (ie go from 1/60 to 1/125, etc.) by one or two (if possible). This will bring down the ambient exposure and make the background darker. This will not affect your flash exposure. Adjusting the aperture, however, will dramatically affect the flash exposure. You then adjust your flash output and flash to subject distance to properly expose for the subject. I use manual power settings with my flash.

If you think about it and go out and try this during the midday, you will quickly see why so many lament over slower flash sync speeds. Pentax' is 1/180s. In bright sun ( sunny 16) an aperture of say f/4 yields a shutter speed ~ 1/2000 (iso 100)! You flash wont fire until you stop down below 1/180s. For easy math that is ~ f/16. Stopping down the aperture one stop cuts your flash power one stop assuming the same flash to subject distance. Hot shoe flashes can't over power the ambient. You then need to move into the shade or wait until the sun starts to go down,etc.

Hope this helps.

03-11-2010, 11:42 AM   #9
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QuoteOriginally posted by MSM Quote

snip..

If you think about it and go out and try this during the midday, you will quickly see why so many lament over slower flash sync speeds. Pentax' is 1/180s. In bright sun ( sunny 16) an aperture of say f/4 yields a shutter speed ~ 1/2000 (iso 100)! You flash wont fire until you stop down below 1/180s. For easy math that is ~ f/16. Stopping down the aperture one stop cuts your flash power one stop assuming the same flash to subject distance. Hot shoe flashes can't over power the ambient. You then need to move into the shade or wait until the sun starts to go down,etc.

Hope this helps.
If you have the flash (external) set to HSS, the flash will fire - it doesn't matter what shutter speed you use.

Back to the OP's question: the 1/60 shutter is the default (for all auto-setting) as soon as the flash is up. Flash photography is entirely different as the metering (exposure) portion of intended subject does not include shutter speed in the equation (instead - distant from the subject). However, it does play a part in controlling and balancing flash light with ambient light. Flash photography is more an art than science, it comes with experience.
03-11-2010, 01:56 PM   #10
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QuoteOriginally posted by aleonx3 Quote
If you have the flash (external) set to HSS, the flash will fire - it doesn't matter what shutter speed you use.
Good point. I don't use HSS (high speed sync). Though, keep in mind that the flash power is markedly reduced and 'pulsated' across the duration of the time the shutter is open, as opposed to a more powerful single flash burst with a regular sync.

Also, I can't remember, but I don't think that I can use HSS with my Metz 48 while using radio triggers. I know that pTTL can't be done.
03-11-2010, 02:25 PM   #11
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QuoteOriginally posted by kewpie-o Quote
It's so funny....over this last year of owning my first dslr camera, I've been learning about aperture, shutter speed, focal distance, and ISO and how they all affect each other. I feel like I have a decent grasp of all of that. Now this flash thing is rocking my world and adds a whole new can of worms to the equation.

Available light photography is like VFR (visual flight rules) flying. Flash photography is kind of like flying with instruments—a whole 'nother ball game.

Will

Last edited by WMBP; 03-11-2010 at 02:49 PM. Reason: fixed spelling error
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