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06-30-2012, 07:08 AM   #1
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Sharpness

Why, when I use flash (in particular softbox) are my shots sharper?
Even when I use high shutter speed, they are not as tack sharp as with flash.
I know how other factors such as depth of field etc. effects it...
Yes, flash is a lot faster, but are there reasons I am missing?
No FF or BF either

Of course, all responses welcome

Thanks

Randy

06-30-2012, 07:19 AM   #2
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What shooting mode was used with/without flash?
06-30-2012, 07:23 AM - 1 Like   #3
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When used properly, you will almost always get sharper photos when using flash, this is due to better contrast breaks (crisp detail highlights, etc..).
06-30-2012, 07:23 AM   #4
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40 years ago, it was because the duration of a flash was the equivalent a 1/100,000 of a second. Someone correct me if I'm searching here. it's hard to remember stuff I listened to in class in 1967. You can never have a shutter speed as short as the duration of your flash. As long as it's reasonably dark around, flash is like having a shutter on steroids.

The other part of that is, if you're not shooting with a tripod, you can do better. All hand held shots can be affected by movement, they may not be if you're good at steadying them, but shooting hand held, take lot's of shots. You can never count on a hand held shot. Take 3 or 4 if you need one. I don't have the steadiest hand, but if I take 4 shots at 1/15 sec. one will be good, maybe 3, but one for sure. You need to find out what your ratio is, and work with it.

06-30-2012, 07:45 AM   #5
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QuoteOriginally posted by normhead Quote
40 years ago, it was because the duration of a flash was the equivalent a 1/100,000 of a second.
I'm pretty sure that's still true with conventional electronic flashes, though I had something like 1/50,000 on my mind. The way I understand it, the shutter will stay open for 1/180 but the actual exposure (in dark enough environment) will only take place during the flash bust, since other light sources are negligible compared to the flash light.
I think the previous answer is right too: if you use a flash you generally get more light and get it from the direction you choose, thus getting a more contrasty shot.
06-30-2012, 07:54 AM   #6
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QuoteOriginally posted by joe.penn Quote
When used properly, you will almost always get sharper photos when using flash, this is due to better contrast breaks (crisp detail highlights, etc..).
This.
06-30-2012, 08:41 AM   #7
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QuoteOriginally posted by normhead Quote
40 years ago, it was because the duration of a flash was the equivalent a 1/100,000 of a second.
Why would flashes be way faster 40 years ago than today, I wonder.

My Alien Bee B800 studio strobes, for example, have the following flash durations.
T.5
1/3300 second (at full power)
1/1650 second (at 1/32 power)

T.1
1/2000 second (at full power)
1/1000 second (at 1/32 power)
Where T.1, for instance, is the time during which the light intensity exceeds 10% of its peak value.

Digital strobes that quickly shut off the flashtube according to the power level of your choice results in the elimination of the decaying tail in the flash duration curve resulting in much faster speeds such as 1/10,000 depending on power level. The small flash units built in cameras and ones you attach are typically that way with variable flash speeds depending on power level. I'll take a guess and say 1/20,000 is about as fast as you'd get without specialized gear but I don't know every flash unit out there.

Last edited by tuco; 06-30-2012 at 09:04 AM.
06-30-2012, 11:24 AM   #8
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Several factors: The typical flash shot stops the lens down more, often to its optimum aperture, giving better resolution and greater depth of field, so more areas are in focus. And as mentioned already, "sharpness" as perceived is a combination of resolution and contrast. The typical flash is a point source of light, giving harsh and distinct shadows and edges, giving an impression of sharpness. Outdoor shots on cloudy days tend to look less "sharp" than in bright sun, even though the resolution of the lens is the same.
The flash impression of sharpness is very apparent in macro photos, due to the more harshly defined texture and edges.
But all this is a matter of taste also. I much prefer non-flash, "available light" pictures, and haven't really used a flash for 40 years.

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