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Old Nov 26, 2004, 8:59 PM   #1
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I have a Panasonic fx7 that I just got. I'm learning a lot about what to do to not get grainy pics in low light situations. When at the limit of the flash range, in auto mode, in a dim room I take a picture. Results: the ISO is set to 400 by the camera, the shutter speed is 1/60 and the pics come out at a good brightness, but they are grainy (expected for a tiny camera at 400 iso). BUT, when I manually set the ISO down to a lower setting like 100, with the flash in auto mode, the shutter speed stays at 1/60 and doesn't get longer! and I get a dark picture as expected.

My question: Why, does the shutter not stay open longer to absorb the light needed for the lower ISO? it does when I don't use the flash and change the ISO levels. Why is it froze at 1/60 when I'm using the flash, even if I need more light?
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Old Nov 26, 2004, 9:10 PM   #2
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1/60 second is a good speed that many manufacturers use with flash.

In most lighting conditions, shutter speed is not critical when using flash. This is because the flash itself has a very short burst (ranging from about 1/1000 second to around 1/10,000 second). So, shutter speed has no bearing on the amount of exposure you get from the flash. The exposure you get from the flash itself is only dependent on aperture (not shutter speed), flash duration (which the camera will control) and ISO Speed (each time you double the ISO speed, the flash range will increase by 1.4x if the aperture and flash duration are the same)

Themain reason that some manufacturersset the shutter speed to around 1/60 second is so that you don't get asmuch motion blur if there arelight sources present other than the flash (for example, open windows during daylight hours). If you set the shutter speed too slow in some lighting, you'd get exposure from ambient light sources (which can lead to motion blur).

In most indoor lighting condtions, it's not a problem (even with slower shutter speeds). This is because the subject is only properly exposed for the duration of the flash burst (so the flash itself freezes the action).
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Old Nov 26, 2004, 9:17 PM   #3
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OK, sounds logical. Guess I'll just have to get closer, or get a camera with a better flash if I'm worried about these situations.
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Old Nov 26, 2004, 9:21 PM   #4
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Or, try Noise Reduction if you need the extra range that ISO 400 provides.

Noiseware (and they have a free version) is available from http://www.imagenomic.com

More choices:

Neat Image: http://www.neatimage.com

Noise Ninja: http://www.picturecode.com

You could also buy a slave flash (designed to fire at the same time as the camera's main flash):

http://www.srelectronics.com/
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Old Nov 26, 2004, 9:39 PM   #5
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WOW! I just tried the imagenomic software on one of my noisy photos, and I got to say I'm impressed. A grainy pic at ISO 400 looks like I took it at ISO 80. Of course, it does average out a little detail, but still, I'm surprised software can remove noise that well.

Thanks.
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Old Nov 29, 2004, 8:54 AM   #6
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Also, in the "old days," SLR manufacturers often used 1/60 second for cameras with horizontal focal-plane shutters because that was the fastest speed at which the entire film plane would be exposed (so neither shutter curtain would block part of the image). SLRs with vertical shutters sometimes used 1/125 and I think there was one Nikon that used 1/250 second (or slower, user's choice) for flash sync.



JimC wrote:

Themain reason that some manufacturersset the shutter speed to around 1/60 second is so that you don't get asmuch motion blur if there arelight sources present other than the flash (for example, open windows during daylight hours). If you set the shutter speed too slow in some lighting, you'd get exposure from ambient light sources (which can lead to motion blur).

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Old Nov 29, 2004, 9:00 AM   #7
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davidl340 wrote:
Quote:
WOW! I just tried the imagenomic software on one of my noisy photos, and I got to say I'm impressed. A grainy pic at ISO 400 looks like I took it at ISO 80. Of course, it does average out a little detail, but still, I'm surprised software can remove noise that well.
I've been pretty impressed with it. As a starting point, use the defaults, then set the sharpening selection in Noiseware up a couple ofnotches (it will automatically go to Custom when you change the defaults). Then, see if you like it even more. ;-)

Then, experiment with the other parameters until you find something that works best for photos taken with your camera in typical conditions when you use a higher ISO speed.





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