ISO for objects.

ISO 100 - finely detailed subject

                                                         ISO 400 - finely detailed subject

                                                        ISO 1600 - finely detailed subject

For the finely detailed subject I prefer the ISO 400 as it gives some grainy texture to the image, but not so much that it's either too dark or that it lessons the detail of the subject. I prefer some grain to add to the detail rather than a smoother image because I believe it enhances the texture.

ISO 100 - smooth, coloured object

ISO 400 - smooth, coloured object

ISO 1600 - smooth, coloured object

For the smooth, coloured object I prefered using ISO 100 as I think it best reflects the brightness and the smooth texture of the apple. Once the image becomes grainier the apple seems to lose some of the reflective texture it had in the ISO 100 image, most noticable in the ISO 1600 image as this creates the most grain.