Jack Loc: Miami FL

High ASA exposition creates more definition in night photoshot. I would like to know the purposes of high ASA/Apertur exposition in daylight photoshoot.

RonaldLewis Loc: Chicago, Illinois

The ASA used to be the film speed but now that has been replaced with ISO which is the sensitivity to light of the sensor.

ShakyShutter Loc: Arizona

The rule of thumb would be to use the LOWEST ISO setting possible letting light conditions dictate of course.

You may be shooting with acceptable shutter speed and fstop settings with ISO 100 outside in daylight. But as evening falls by increasing the ISO setting you can maintain acceptable shutter speed and fstop settings in much dimmer light. However, the trade off is that as you increase the ISO you also increase the amount of digital "noise" in each photo. This would be imperceptible to you going from ISO 100 to about ISO 400. At that point even an untrained eye can see the loss of detail and increase in the noise displayed in the photos.

MPratter Loc: Pittsburgh, PA

I might use a high ISO film in day light to maximize depth of field and to make the picture grainier.

Usually I want a very narrow depth of field with a huge aperture, so I use very low ISO stock in the 25-50 range.