Use whatever ISO you need to use the light you have with your speedlite, to get the shots you want and need.
If you are shooting in a small room with light colored walls, and are close to your subject, use ISO 100. But sometimes your poor little speedlite won't have enough light in a big room with darker walls when the subject is 15 feet away. Raising your ISO from 100, to 1600 gets you effectively 4 more stops of light - 200, 400, 800, 1600 - that is a lot more light, that you can bounce of ceilings, or walls, etc.
So - Yes, a lower ISO is generally preferable all other things being equal, but they rarely are equal, and raising the ISO can help you bring home the bacon.
Modern DSLRs can capture very pleasing images at high ISOs if they are exposed correctly and are not under exposed.
Try to use as low an ISO as possible. If it's a large room, as mentioned, a hot shoe flash won't put out enough power, and you may need to raise the ISO so your camera captures more light.
does it matter what ISO I use when I use a flash indoors? I will try to use a canon 580 flash to shoot boxing.
You have multiple considerations that determine what ISO you want to shoot with when using a flash indoors.
If you are using your flash for foreground illumination and still want some ambient exposure on your background (so it's not too black), then you will need to find a shutter speed, aperture, ISO that gives you decent background exposure where the flash doesn't reach. This would basically be the same exposure as taking a non-flash shot of the background, so if it's dark, you will probably need to raise your ISO in order to get a decent exposure there.
If you need more range from your flash, you can raise the ISO to get more range. Your flash has twice as much range as ISO 400 as ISO 100.
If you are trying to "stop" some fast action with your flash, then you probably want to kill any effect of ambient light on the exposure so that the short flash pulse is the only relevant illumination in the shot. In this case, you either need a small aperture, a low ISO or some combination of the two. This is generally the opposite effect in item 1 above.
I'd say your very first consideration is to understand the range of your flash at the aperture you'd like to shot and your base ISO. If you need more range, then you will immediately have to up the ISO and there's no need to discuss the other issues.
Your second consideration is how you are going to stop the action in the boxing. Since it sounds like you already know you need to use the flash and you want to stop the action, you're going to have to go for option 3 above. I'd set your shutter speed to around 1/200th, set the camera to your base ISO and then look at how much ambient exposure there is at whatever aperture you'd lke to shoot at. To "freeze" the motion with your flash, you want ambient to be 2-3 stops underexposed so it won't have any serious effect on the final result. In some cases, you may have to stop down a little to kill the ambient. I generally run the camera in manual mode at this point because you want to control ISO, aperture and shutter speed while letting the camera/flash pick the flash power.
Is the boxing match televised? If so...and even maybe if not, there will probably be nearly enough light without flash. I would think that anything less than 1/250 will likely have motion blur from your subjects swinging....and some will be blurred at that speed as well. Where will you be seated? If you are not ring side, you may have more trouble with flash than without...by illuminating distracting elements between you and the ring. In your shoes, Id set my shutter speed at 1/250 in manual. If ringside using a 17-55mm zoom, an apeture of F4...and use an ISO that will get me a proper exposure according to the camera's meter. If there isn't enough light for proper exposure, then setting the flash at auto ETTL will finish the job.
Comments
If you are shooting in a small room with light colored walls, and are close to your subject, use ISO 100. But sometimes your poor little speedlite won't have enough light in a big room with darker walls when the subject is 15 feet away. Raising your ISO from 100, to 1600 gets you effectively 4 more stops of light - 200, 400, 800, 1600 - that is a lot more light, that you can bounce of ceilings, or walls, etc.
So - Yes, a lower ISO is generally preferable all other things being equal, but they rarely are equal, and raising the ISO can help you bring home the bacon.
Modern DSLRs can capture very pleasing images at high ISOs if they are exposed correctly and are not under exposed.
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You have multiple considerations that determine what ISO you want to shoot with when using a flash indoors.
- If you are using your flash for foreground illumination and still want some ambient exposure on your background (so it's not too black), then you will need to find a shutter speed, aperture, ISO that gives you decent background exposure where the flash doesn't reach. This would basically be the same exposure as taking a non-flash shot of the background, so if it's dark, you will probably need to raise your ISO in order to get a decent exposure there.
- If you need more range from your flash, you can raise the ISO to get more range. Your flash has twice as much range as ISO 400 as ISO 100.
- If you are trying to "stop" some fast action with your flash, then you probably want to kill any effect of ambient light on the exposure so that the short flash pulse is the only relevant illumination in the shot. In this case, you either need a small aperture, a low ISO or some combination of the two. This is generally the opposite effect in item 1 above.
I'd say your very first consideration is to understand the range of your flash at the aperture you'd like to shot and your base ISO. If you need more range, then you will immediately have to up the ISO and there's no need to discuss the other issues.Your second consideration is how you are going to stop the action in the boxing. Since it sounds like you already know you need to use the flash and you want to stop the action, you're going to have to go for option 3 above. I'd set your shutter speed to around 1/200th, set the camera to your base ISO and then look at how much ambient exposure there is at whatever aperture you'd lke to shoot at. To "freeze" the motion with your flash, you want ambient to be 2-3 stops underexposed so it won't have any serious effect on the final result. In some cases, you may have to stop down a little to kill the ambient. I generally run the camera in manual mode at this point because you want to control ISO, aperture and shutter speed while letting the camera/flash pick the flash power.
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