Originally Posted by
DanK
Let me back up a bit.
There are two ways to create a stack: move the camera toward or away from the object, or change the point of focus by rotating the lens barrel. Except for some practical questions, it doesn't make any difference which you do. What matters is that you get the right interval between shots so that you don't leave anything out of focus. There is no need for a rail, although you might find it easier to use. You can accomplish the same thing by rotating the lens barrel. I own a good rail, and I use it to help make fine adjustments for framing the first shot, but I don't use it after that to create the stack. I could, but I just am in the habit of rotating the lens instead, and I would have to figure out how much to turn the knob on the rail to get the right intervals.
I believe the function in Control my Nikon that George is referring to is controlling the change in focus via the software if you are shooting tethered. The software I own for that is Helicon Remote (not Helicon Focus), which works on both PCs and Macs. Once you figure out the settings for your particular lens (the defaults were not correct for mine), you simply focus on the closest and farthest points that you want in focus and indicate those to the software. The software then takes the necessary number of photographs, rotating the lens itself. It's in some ways very neat, but I found that I never use it. I just change focus manually. I have done it so long that I know how much to rotate the lens.
None of this helps with shooting bugs, unless they are very cold and slow-moving.