Module 02
Find focus in the dark
Practice a repeatable focus check when autofocus begins to hunt.
Lessons
- Choose a distant reference
- Use magnified live view
- Check corner sharpness
- Keep a field notebook
Give focus a useful target
A dark sky often has too little contrast for autofocus. Find a distant point of light or a bright edge, such as a building against the sky. Use that to establish focus, then return to your composition without changing the focus ring.
If the lens permits it, switch to manual focus after the first check. Magnify live view and turn the ring slowly in both directions. You are looking for the narrowest, cleanest edge. Avoid judging sharpness from a reduced preview alone.
Verify the photograph
Make a test exposure and examine the center and corners. A lens can render the middle sharply while stretching bright points near the edges. Stop down slightly and repeat if the shape of the light matters to your picture. Keep shutter speed and ISO notes alongside the aperture.
Do not assume every blurred light is a focus error. Movement can draw a short line across the whole frame. Condensation can spread light into a soft patch. Check the tripod, lens surface, and focus independently before changing several settings at once.
Keep a useful record
Record the lens, focal length, aperture, and how you established focus. Note the part of the frame you checked. On the next evening, those notes give you a practical starting point. Recheck after a temperature change, an accidental knock, or a new focal length.