Hi all, I built a simple pinhole camera with my son made out of cardboard that uses 4X5 sheet film. The distance from the pinhole to the film is about 6 inches. I have been having trouble getting good images with my hand punched pinholes (sewing needle) exposure is OK but the focus seems poor. I am pretty careful to keep it steady.

Is there are way to get more precise pinholes other than using a sewing needle? I may be mis-calculating the pinhole diameter needed for the focal distance.

Thanks in advance for your advice.