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What does changing the ISO on a digital SLR like the D70 actually do? Does it work on the same principle as with a film SLR? Your incredible insights would be appreciated.

Regards

Peter Mc PS Is there an easy way to put a piccy on my posts?

Gidday Peter,

ISO works the same.

Doubling the iso value is equal to one stop of extra sensitivity, which means that one stop faster shutter (double shutter speed can be used) or one stop smaller aperature can be used in a given situation.

Cheers

Hi Peter, Not sure what you mean by putting a pic on your posts? If you mean putting a little pic on every post under your name that is an avatar and is done by the profile button which is at the top of the page in the middle. If you mean putting a pic in one of your posts, Stubbsy has made a guide here: http://www.d70users.com/viewtopic.php?t=2789

Good luck

The principle in terms of exposure is much the same as film. The consequence is also similar, but instead of increased grain you get "noise"

There are programs which can reduce the appearance of noise.

petermmc wrote:What does changing the ISO on a digital SLR like the D70 actually do? Does it work on the same principle as with a film SLR? Your incredible insights would be appreciated.

Your question in photographic terms has already been answered - but in case you were wondering what the mechanism behind it is, increasing the iso amplifies the output from the CCD, as well as changing the exposure meter calculation. So, like any amplification, the noise (grain) is increased as well as the signal (picture). It's like changing the exposure and the film at the same time.

Changing the iso on a film camera doesn't do anything except modify the exposure meter parameters, but I'm sure you already knew that!

Cheers

Thanks for those replies. Is it the CCD that becomes more sensitive? If so, how does this happen? I assume you can get the same effect by using manual or is this a different thing?

Regs

Peter

 AFAIK, the actual output from the sensor is amplified.

The real use of ISO is allowing you to have a correct while maintaining a fast enough shutter speed and an aperture that you want.

petermmc wrote:Thanks for those replies. Is it the CCD that becomes more sensitive? If so, how does this happen? I assume you can get the same effect by using manual or is this a different thing?

Regs

Peter

The amplifiers that the ccd is connected to are "turned up". You cannot get the same effect by underexposing using manual, then adjusting later in PP. Try it and you'll see the difference!

Cheers

Well answered.

Thanks for your assistance.

Peter Mc