Looking to shoot star trails and milky way with an a900. Can anyone tell me what the highest useable iso is for this application? Thank you!!
There is no one 'highest useable' ISO. The noise of one ISO setting might be acceptable to one person, but not another.
My guess would be around 1000 ISO. I shot the Nikon D3x for about five years and if my memory serves me correctly the two cameras shared basically the same sensor. With an adequate exposure Nikon was good to up to around 1000 to 1250 ISO But as was mentioned above what one person might consider acceptable another person would not consider good...
