Quote:
Originally Posted by Rossco  What's the optimum ISO to use on a bright day if you're using a ring-flash? |
You really need to use some trial & error - it's very hard to work out because the resulting exposure will depend on the ISO, the lens, the aperture, the shutter speed & the distance to the subject.
ISO just controls the sensitivity of the sensor but the trade-off is that the faster you set it, the grainier your photos will look - so a slower ISO will give you a better quality image but needs more light. In natural light you might have to use a higher ISO to compensate for low light conditions but if you are providing your own light (a flash) and you are close to the subject then there's no reason why you shouldn't set a low ISO and get a better quality image.
I raised the issue because in your example photo it looks like the aperture is a bit wide and the flash isn't dominating the lighting so it has allowed a little movement to create some blur on the image. If you drop the ISO down to 100 or 80 then the sensor will need more light to make a proper exposure and if you use a small aperture (eg. f11 to f22) this will again reduce the amount of light getting to the sensor ... thus reducing the influence of the sunlight and allowing the flash to have some freezing effect on the photo
But just try out a few things and see what works best for you