Last year I went to the race track at night and was using my Nikkor 50mm 1.8. I went over the images again and the settings were coming out to 1/40s @ f/2.8 and ISO 1600. Now if I pull out my Tamron 17-50mm f/2.8 and shoot a 50mm w/ ISO 1600 @ f/2.8 will my shutter speed be the same? The reason I'm asking is because I currently have the above lens and I'm also looking to pick up a Tamron 70-200 f/2.8 shortly. I'm assuming with all these lenses the shutter speed should be the same across all their focal lengths at the same ISO. Am I right in thinking this? I wasn't sure if actual lenses would change this. If it is I'm hoping I can get acceptable images at 1600 on my D300, the D80 wasn't very nice at that ISO setting. I haven't really tried it's higher ISO settings yet. That's another thread though.