ISO settings

I have had my D3000 for a while but still haven't explored my ISO setting. I have had many people ask me to take portraits of them and was wondering if this has any importance in a shoot, will it affect a pic once it gets blown up to a 11x14 or 16x20.

Hi Christina...Welcome...High ISO wont effect a printed picture but noise generated by it can...

The higher the ISO the higher the noise....

I usually have the ISO in my camera set at ISO200 so there isn't a lot of noise

The basic answer to your question is Yes... The higher the ISO, the more noise is introduced... if you subsequently increase the image size, the noise becomes more apparent as sort of a grainy effect...

In a studio setting (generally) you control the lighting. That allows you to maintain/use a low ISO setting. The lower the setting, the less noise. At ISO 100-200, there is almost no noise with today's sensors... You might want to review the ISO settings in your camera, and select a low ISO, as opposed to letting the camera setting of ISO-Auto select the ISO...

If you do experience unacceptable "noise", then there are software methods in post-processing to eliminate the noise. There are even specialized software programs for correcting this single issue...

That's not say you shouldn't experiment with higher ISO settings when the situation warrants it...