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本帖最后由 gzhjb 于 9-5-2021 12:47 编辑
Flash Basic
Shutter speed is much slower than the duration of the flash, so think of it as just controlling your ambient light, this is because no matter how slow or fast the shutter speed is, up to the sync speed (normally 1/200 second), of course, it won't be as fast as the flash. So whenever the shutter is open, it'll take in all of the flash lightings, but the longer you leave your exposure, the more ambient light you'll let into the camera.
Your ISO and aperture controlled both flash and ambient light. This is because, with aperture, you're increasing or decreasing the size of the hole that the light can get through, and with ISO, you're changing the application of the signal from the sensor. So these control the overall exposure of your photograph. And then we have the flash power setting, this comes as fractions, 1/1 being full power, 1/2 being half power, 1/4 being quarter power, and so on and so forth, right down to 1/128. The lower the power, the longer the batteries will last in your flash, and also the quicker the recycle time.
One other thing to take into consideration is that for each fraction change that you make in the power on the flash, this changes the flash brightness by one stop. So 1/4 to 1/2, would be the same as F5.6 to F4, or ISO 100 to ISO 200, and 1/4 to 1/8 on the flash would be the same as F5.6 to F8, or ISO 100 to ISO 50.
Now you might be wondering why I haven't included shutter speed and the reason for this is that really short duration of the flash, no matter how long or short the shutter speed is, as long as you're below the sync speed (normally 1/200 second), it'll take in all the power of the flash, so it doesn't matter what shutter speed you're at, the flash power will be exactly the same. And for now, this is all you need to know about your flash. You can have it in manual mode and you're gonna change the fraction of power that you're going to use, so as long as you understand stops of light, and you know how aperture, shutter speed, and ISO work together, this fractional change should seem quite familiar.
One other thing to take into consideration is the flash duration, especially if you have things moving fast through your frame the closer to full power that you are on your flash unit, the longer the duration of the flash, so if something's moving fast through your shot, it's more likely to blur. If your subject starts blurring due to motion when you're using a flash, you may have to reduce the power, which will reduce the duration of the flash, more likely freezing your subject, and do remember to increase your aperture or ISO to compensate for this decrease in flash power.
I start off with the following settings. I put the shutter speed at around 1/100 second, my ISO at 100, aperture at F5.6 and I set the flash to manual and 1/4 of the power, I set my white balance to Flash. If you're using a mirrorless camera, you'll have to turn the live view display off to see what you're shooting. Once you've done this, take a test shot, one quick tip to get much better light from your flash instantly is to tip the head of the light-up towards the ceiling, as long as you got a white ceiling, it'll give you a really nice light. This will bounce the flash off the ceiling, making the flash a much bigger light source and making the light a lot softer. It will dissipate the intensity, so you may have to increase the flash power if needed, then you want to play around with your shutter speed and flash power to get the right ratio between the two sources of light, once you've got this, you can adjust your aperture to get good overall exposure and this is where personal taste comes into play. You might like more flash or you may prefer more ambient light, but knowing how to change each light source is critical to get what you want. If I want more ambient light, I'll lower my shutter speed, if I want less ambient light, I'll increase my shutter speed. You just need to make sure when increasing your shutter speed, you don't go faster than the sync speed (normally 1/200 second). If I want just the flash to be brighter, I'll increase the flash power, if I want the flash to be darker, I'll decrease its power. So very quickly you can dial in your settings by just thinking of shutter speed for ambient lights and flash power for flash.
When dialing in my settings, if I want there to be very little ambient light, and all flashlights, I'll have my shutter speed set at the max sync speed which is 1/200, then I'll increase the power of the flash and then control the overall exposure with aperture.
If I want to blend ambient and flashlight, what I'll do is I'll decrease my shutter speed (so getting more ambient light) and then play around with both shutter speed and aperture. If I then need to increase or decrease the flash compared to the ambient light, what I'll do is change the power on the flash. All I need to do now is change my aperture to change my overall exposure because I've balanced the ambient light outside and the flashlight inside together to where I want them to be. It does take a while to get your head around this but once you do, you'll be able to dial in those settings really quickly and then you have ultimate control over your flash and ambient light. You'll also be able to get really consistent results that you wouldn't do in maybe an auto mode or TTL mode.
The next thing to think about is how you use the flash head to disperse that light. If you have it pointing directly at your subject, it'll be a really harsh hard light, because that light source is really small. If you have one of these flash units with a moveable head, what you want to try and do is bounce it off different surfaces in the room that you're in, as long as the surfaces aren't black, they will bounce that light back and they'll normally create a much bigger light source, so in using the basic principles that I've just taught you, try tilting the head of the flash towards to a big wall or a big ceiling, just to see how the light changes, you can grab a family member and use them as a subject or if you have a remote shutter, you can take photos of yourself.
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