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<blockquote data-quote="BackdoorArts" data-source="post: 434742" data-attributes="member: 9240">Base ISO is the value at which the sensor naturally captures light information (for almost all current Nikons that is ISO 100).&nbsp; Any deviation from that value, both up and down, requires either the amplification or attenuation of the light information.&nbsp; In other words, software interprets the natural light in a way that allows you to shoot faster or slower.&nbsp; This interpretation will always introduce artifacts (i.e. noise) into the process with the amount depended on the level of manipulation.&nbsp; As a musician I like to think of ISO in terms of a tube guitar amplifier.&nbsp; There's a sweet spot, say around 5 on the volume, where everything sounds crisp, clean and perfect.&nbsp; If I turn down it's still &quot;clean&quot;, but the tones may be dull and muted.&nbsp; If I turn up I begin to get distortion.&nbsp; In each case, the further away from the sweet spot (i.e. Native ISO) the more pronounced the effect.&nbsp; Just how pronounced will depend on the amplifier circuit (i.e. the sensor physical design and firmware ability), which is why some are able to get much louder than others and stay clean.(back to cameras)...The manufacturer will tend to only give you access to ISO values it deems &quot;usable&quot;, which means you can expect to have an image that is recognizable and will function, at a minimum, as an accurate recording of the event.&nbsp; In general this will mean that the high values will have some &quot;significant noise&quot; seen when compared to native ISO, but that may be more than usable for a given purpose - particularly given the plethora of noise reduction tools available in post processing.&nbsp; What I &quot;avoid&quot; will differ by situation.&nbsp; For instance, if I am shooting birds then I want to see detail in the feathers, which can be lost when implementing noise reduction.&nbsp; On my D7000 that meant nothing above 1600.&nbsp; On my D7100 that means nothing above 3200 if I can help it, but 6400 is fine provided I don't need to crop significantly.&nbsp; That said, I had no issue shooting concerts on the D7000 with values above 1600 because I could deal with the noise more readily in those situations.</blockquote>

[QUOTE="BackdoorArts, post: 434742, member: 9240"] [B][I]Base ISO[/I][/B] is the value at which the sensor naturally captures light information (for almost all current Nikons that is ISO 100). Any deviation from that value, both up and down, requires either the amplification or attenuation of the light information. In other words, software interprets the natural light in a way that allows you to shoot faster or slower. This interpretation will [I]always[/I] introduce artifacts (i.e. noise) into the process with the amount depended on the level of manipulation. As a musician I like to think of ISO in terms of a tube guitar amplifier. There's a sweet spot, say around 5 on the volume, where everything sounds crisp, clean and perfect. If I turn down it's still "clean", but the tones may be dull and muted. If I turn up I begin to get distortion. In each case, the further away from the sweet spot (i.e. Native ISO) the more pronounced the effect. Just how pronounced will depend on the amplifier circuit (i.e. the sensor physical design and firmware ability), which is why some are able to get much louder than others and stay clean. (back to cameras)... The manufacturer will tend to only give you access to ISO values it deems "usable", which means you can expect to have an image that is recognizable and will function, at a minimum, as an accurate recording of the event. In general this will mean that the high values will have some "significant noise" seen when compared to native ISO, but that may be more than usable for a given purpose - particularly given the plethora of [I]noise reduction[/I] tools available in post processing. What I "avoid" will differ by situation. For instance, if I am shooting birds then I want to see detail in the feathers, which can be lost when implementing noise reduction. On my D7000 that meant nothing above 1600. On my D7100 that means nothing above 3200 if I can help it, but 6400 is fine provided I don't need to crop significantly. That said, I had no issue shooting concerts on the D7000 with values above 1600 because I could deal with the noise more readily in those situations. [/QUOTE]

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