Originally Posted by jaor.s2k

Depends what you want in your lighting situation. Having a greater aperture will actually make the the overall photo more in focus. For example: the subject and background will be in focus more compared to a lower aperture where you can blur out the background or foreground depending on your focus (also called bokeh), If you are around f/1.4-f/2 you will see that even parts of your subject are out of focus or blurry. So having a an aperture of f/8 should be sharper than f/5.6

But the main reason to play with aperture during light painting is exposure of light. So if you wanted more light exposing the sensor, you would have a lower aperture because it opens up the lens more so more light hits the sensor. So technically M-type is right about using a lower f/, but not for a sharper image, but for more light exposure. This also plays in tangent with your shutter speed, so lower aperture you can have a faster shutter speed and higher aperture you will need a slower shutter speed to get the same light exposure, but images will differ, sometimes big, depending on the difference of change in aperture.

A wobbly tripod definitely doesn't help, especially if you don't use a timer or remote. Whenever I light paint, I always use a timer. The reason for this is because the small movement for pressing the shutter, can cause a blur in your photo, this is even more so with the tripod issue. I also use a timer so that I don't lose any light painting time walking from camera to car, as soon as the shutter goes off, I am by the car ready to light paint.


Hope this helps!