OK, so I made the jump from a D40X to a D90. I have been incredibly happy with my upgrade, but wanted to ask some Nikon experts a ? about ISO.
On the D40X, my lowest ISO was 100. Since I mainly do studio portraiture, that is perfect for me.
On the D90, the lowest ISO is 200, but then there is "lo" options. Are they even useable? Why are they termed "lo"? I'm still learning the ins and outs of my new gear, so please forgive this lurker if this question is lame. I just hear talk about useable high ISOs and was wondering about the low end too. Thoughts? Opinions? Educate me oh wise Nikon brothers and sisters!