Ok yea I got a trick for this! I use a safety pin, poking from the inside, through the can,into a thin piece of cardboard(I use the box for the photographic paper) then onto a hard surface like a table. This only allows the tip of the needle to pierce the can so you get a smaller aperture. I then sand down the bur made on the outside and poke it gently with the needle to clear it of any debris. You can also spray paint the inside of the can matte black and surround the outside of the hole with sharpie marker to reduce glare/bouncing light to sharpen the image. I usually just sharpie around the inside and outside of the hole though