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pjd
01-30-2007, 12:25 PM
Fairly straightforward q- we have an F30 which has obvious capabilities but in this regard I find it hard to use. If I suppress the flash do I really need a tripod/ solid base?

mattdm
01-30-2007, 12:45 PM
It depends on the lighting. And clearly, turning off the flash decreases the available light.

Watch the shutter speed. If it's getting below 1/60th, it's hard to hold the camera still (not to mention the subject). The camera actually puts up a little warning shake icon in this case. With some care, I've found I can hold the F20 acceptably steady down to 1/10th of a second or so (but then you really have to watch to make sure what you're photographing holds still too).

reppans
01-30-2007, 06:18 PM
The F30 is supposed to be good at high ISO.... so increasing the ISO can give you reasonably fast shutter speeds without having to use a flash. Higher ISO will always tend to be a bit grainier/noisier than lower ISO though - that's the trade off.

pjd
02-01-2007, 06:30 AM
I've obviously not previously properly understood the relationship between ISO/ shutter speeds. Big help!

Thanks.

mattdm
02-01-2007, 07:42 AM
I've obviously not previously properly understood the relationship between ISO/ shutter speeds. Big help!


It's pretty important to understand. For any given scene, there is a correct exposure. There are three factors in every camera which can be adjusted to get that exposure -- shutter speed, aperture, and ISO. "Factors" is a really good term, in fact, because you can think of it as "aperture shutter speed ISO = exposure". That is, just like 2610 and 835 both equal 120, you can decrease one parameter if you raise the others the exact right amount to compensate.

Shutter speed and ISO are rather obvious -- 1/30, 1/60, 1/120 are all doublings of speed. ISO 100, 200, 400, same thing. So 1/30 at ISO 200 is the same as 1/60 at ISO 400 -- decrease the shutterspeed by half and you have to double the ISO.

Aperture appears more confusing, but the important thing to remember is that each standard F stop -- f/1, f/1.4, f/2, f/2.8, f/4, f,5.6, f/8, etc -- also is exactly a halving of the amount of light allowed in. So if you keep ISO constant, 1/30 at aperture f/4 is the same exposure as 1/60 at f/2.8.

So, there's lots of ways to arrive at the correct exposure for a given scene. Often, you're limited by technical constraints -- most lenses don't have wider apertures than f/2.8 (or less for long zooms), ISO is a pretty limited range, and you can't always take a 2 minute exposure. But, within these limits, these variables give you technical/artistic/editorial choice, because each factor has its own tradeoffs.

SpecialK
02-02-2007, 10:57 PM
It's pretty important to understand. For any given scene, there is a correct exposure. There are three factors in every camera which can be adjusted to get that exposure -- shutter speed, aperture, and ISO. "Factors" is a really good term, in fact, because you can think of it as "aperture shutter speed ISO = exposure". That is, just like 2610 and 835 both equal 120, you can decrease one parameter if you raise the others the exact right amount to compensate.

Shutter speed and ISO are rather obvious -- 1/30, 1/60, 1/120 are all doublings of speed. ISO 100, 200, 400, same thing. So 1/30 at ISO 200 is the same as 1/60 at ISO 400 -- decrease the shutterspeed by half and you have to double the ISO.

Aperture appears more confusing, but the important thing to remember is that each standard F stop -- f/1, f/1.4, f/2, f/2.8, f/4, f,5.6, f/8, etc -- also is exactly a halving of the amount of light allowed in. So if you keep ISO constant, 1/30 at aperture f/4 is the same exposure as 1/60 at f/2.8.

So, there's lots of ways to arrive at the correct exposure for a given scene. Often, you're limited by technical constraints -- most lenses don't have wider apertures than f/2.8 (or less for long zooms), ISO is a pretty limited range, and you can't always take a 2 minute exposure. But, within these limits, these variables give you technical/artistic/editorial choice, because each factor has its own tradeoffs.

Excellent explanation, except..."1/30, 1/60, 1/120 are all doublings of speed..." is actually halving of speed, not doubling. Easy mistake :-)

pjd
02-14-2007, 04:15 PM
Mattdm

belated thanks for that reply. Much appreciated.

core!
02-15-2007, 06:44 PM
Excellent explanation from you dear Mattdm,will help me a lot in long run thanks!

mattdm
02-15-2007, 07:06 PM
Excellent explanation, except..."1/30, 1/60, 1/120 are all doublings of speed..." is actually halving of speed, not doubling. Easy mistake :-)

I actually meant it that way -- doubling of time, halving of speed. :)

But you're right, that's not really very clear, because of course it's not really speed but time.

Norm in Fujino
02-15-2007, 10:40 PM
I actually meant it that way -- doubling of time, halving of speed. :)

But you're right, that's not really very clear, because of course it's not really speed but time.

Well, one can think of it as the speed of the shutter that's doubled.