Petri, originally called Kuribayashi, was a Japanese camera and optics company founded in the early 1900s. The company produced many different types of cameras, including single lens reflexes (SLRs), compact rangefinders, twin lens reflexes (TLRs) and large format folding cameras. Though the company stopped making cameras in the late 1970s, many Petri cameras, especially fixed lens rangefinders, can be found on the vintage market. As most of these cameras are over 40 years old, light repair work and cleaning is commonplace.
Open the film door by pulling up on the film rewind knob, located on the top right of the camera body. Older Petri rangefinders have a small tab on the left side of the body that you must pull down to open the film door.
Scrape out the old, crumbling seals from the grooves at the top and bottom of the film chamber using a toothpick. Blow out any small particles from the grooves using an air blower.
Cut two lengths of thin black yarn to fit into the grooves.
Press the yarn into the grooves using your toothpick. Pressure from the film door helps to seat the yarn permanently, so avoid using any glue or adhesive. Leave the film door open.
Push the film advance lever forward to cock the shutter. Watch the lens as you press the shutter button to ensure that the camera's shutter blades open and close properly.
Rotate the aperture ring at the front of the camera's lens barrel. Check that the diaphragm blades, which determine the amount of light entering the lens, respond to the ring's rotation.
Alternate between pushing the film advance lever and pressing the shutter button to exercise the camera. Often, this continuous exercise frees up sticky internal mechanisms and redistributes dried lubricant.
Loosen a sticky focus ring by leaving the camera on a warm, sunny windowsill for several hours. Rotate the focus ring back and forth to redistribute the warmed lubricant. If this doesn't help, apply two small drops of denatured alcohol to the seam between the focus ring and lens barrel. Rotate the ring continuously to spread the alcohol.
Blow away dust from the front element of your camera's lens. Moisten a microfiber cloth with lens cleaning solution and swab the lens clean using a gentle circular motion.
Many Petri cameras are fully mechanical, meaning that no battery is required for use. If your camera requires a battery, open the chamber cover and clean away any corrosion using an eraser. Insert a replacement battery and close the cover. If you have a Petri SLR camera, remove the lens and blow out any dust inside the camera. Fire the shutter to check that the internal mirror flips up and back down as it should.
Do not attempt extensive repair work on your Petri if you are not familiar with camera mechanics. Bring your camera to a professional repair service if the shutter, film advance lever or other internal mechanism require attention.