Depth of Field (DOF) is often forgotten by a lot people. They just open their apertures to the max whenever they shoot in dark environments. Often, the pictures come out blurred. It may very well be that the DOF was too small in those situations.
My own DOF calculator
I’m always screaming about Depth Of Field and how you should be aware of this. So I could not resist to put my own DOF calculator online. As of today, you can visit my DOF calculator here: XHD DOF Calculator.
In time I will be expanding this calculator page, possibly add some graphics and explanation links to what the numbers really mean.
For now, play around with it. Any feedback is welcome!