On-the-Spot Diagnosis: Meeting a Seller at a Café Without Your Laptop

Picture the scenario: you've met a used camera seller at a park bench or café. No laptop handy. How do you assess the health of a mechanical shutter in 5 minutes using just the camera and a phone?

Here are 5 field-tested express checks from my repair shop practice.

5 Field Tests for Shutter Mechanics

1. Test 1: Shoot a bright surface at 1/8000s (or 1/4000s): Point the camera at a whitewashed wall or open sky. Take a shot at the shortest available shutter speed. Open the image on the LCD and zoom in. There should be no dark horizontal bands or gradient darkening at the frame edge! (Dark band = one curtain lagging behind the other.)
2. Test 2: Visual curtain inspection with a flashlight: Remove the lens and activate Mirror Lock-Up for Cleaning in the menu. Shine your phone's flashlight into the mirror box toward the curtains: the blades should be perfectly flat, with no waves, scratches, or oil spots.
3. Test 3: The "Audio" Burst Test in CH mode: Fire a short burst of 5 frames. The sound of each actuation should be even and rhythmic, without metallic squeals or timing gaps.
4. Test 4: Send a RAW File to Your Phone via Telegram: Ask the seller to forward the uncompressed file to you in a messenger and immediately upload it to our service right from your phone!

Field Self-Diagnosis Table

Express Test	Sign of Healthy Shutter	Sign of Failure / Wear
Shot at 1/8000s	Uniform brightness across the entire frame	Black band at top or bottom of frame
Curtain inspection with flashlight	Matte, flat blades without oil	Ripples on blades, dents, lubricant droplets
CH burst sequence	Sharp, rhythmic click	Grinding, frame timing gaps, Err error