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 p.1 #7 · Question about flash and shutter speed | |
Hmm, this is not really a dumb question, it's actually one of the things that many people find the most difficult to "Wrap their head around." The topic can be somewhat technically complex if you choose to make it such, but let me see if I can shed some light on this for you. This isn't 100% technically accurate, but it'll hopefully help.
When you start using flash, you have the 'sync speed' which is essentially the fastest shutter speed you can use with a flash. This is 1/200 or 1/250 on most cameras. If you need a faster shutter speed, your only options are High Speed Sync (if your particular setup supports it), or to risk catching your shutter in motion. High speed sync loses *ALOT* of your distance/output power really quickly (inverse square property of light). If you catch your shutter in motion, what you'll notice is that there is basically a line through your image where it's substantially darker.
So now the big question I have is. What are you trying to accomplish by changing your shutter speed. Contrary to what you would actually tend to think, increasing the shutter often times does not actually help you with things like motion blur (except for extremely fast subjects.) One of the properties of dealing with flash, is that it tends to "Freeze" an object in motion. So while not technically accurate, a 1/200 w/ a flash can appear more crisp than a 1/200 w/ ambient. Just different beasts.
Also important to note, is how to properly expose with flashes, if that's your problem. Generally speaking, the shutter speed will control your ambient light, and your aperature controls your flashes. That is to say, whatever the flash isn't lighting up, (ie the background or area's outside of the path of the light from the flash) will be best exposed by adjustments to theshutter. The Aperature/flash power is what really effects how much flash is visible. If you're seeing too much flash, use a smaller aperature. This is partly why things can get so confusing, most people often think "use a larger aperature to get a faster shutter speed to freeze motion" and here I'm mentioning use a 1/200 shutter and a f/11. It's just a bit backwards from what most people intuitively feel. ISO tends to impact both. So on a brightly lit day it's not uncommon for me to be shooting ISO 100, f/11, 1/200 shutter.
PS Some of the best scenario's for flash is when the subject is about 2 stops separated from ambient in my experience. (But this definately varies on circumstance.)
Anyways, maybe give me some more details about what you're trying to accomplish and we'll see how we can help.
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. The old CCD chipped cameras ie the 1D and older Nikons (DX format) had a shutter sync speed of 1/500th (canon 1D) or higher (Nikon users please correct, I believe only achieved with dedicated Nikon flashes). Unfortunately the CMOS chips are limited generally to 1/250th or so 
. Back in the "old" film days Metz made some units that would sync at a very high speed (note the units are very expensive, etc... don't know if they will work with DSLR's).
. Come to think of it, it never rains inside a hockey rink!