One of the biggest things I have had to learn over the last year is to understand how the camera settings interact with each other to create the picture. It is something that I am still learning to be honest. There are lots of nuances that I don’t have yet. And I can’t do the reciprocals in my head yet for getting the exposure that I want.
I find it really fascinating how ISO, aperture and shutter speed all tie into the exposure. They can make the background black and the subject perfectly exposed. They can cause motion blur in just the right spot. Too much of one and the picture is overexposed. To little and the picture is dark and you can’t see anything.
I feel the key to learning how your settings interact is to take pictures of the same thing with changes in the settings. That way you can really see what the happens. And I think one of the trickiest, but best, things to practice on is the moon. You can either get a big white blob with no detail, a faint mis-colored disk in the sky or a really cool detailed shot of the moon showing the lights and darks.
Here is the best shot I have ever gotten of the moon.
1/500 sec, f 5.6 ISO 200, 300mm