Camera Problems Troubleshooting

Film cameras are mechanical devices, and mechanical devices develop problems. Learning to diagnose camera issues saves wasted film and helps you decide when a camera needs professional service versus a simple fix.

This guide covers the most common camera problems, how to identify them, and what you can do about them.

Light Leaks

Light leaks are the most common film camera problem. Light enters the camera body through worn seals, cracks, or gaps, fogging the film.

Symptoms on Film

• Red or orange streaks (colour film) along frame edges
• Light bands or patches that don't correspond to the scene
• Fog that varies frame to frame (depends on how camera was held relative to light)
• Consistent fog in the same location across multiple frames
• Fog worse in bright conditions

Common Light Leak Sources

35mm SLRs:

• Door hinge foam (most common)
• Mirror box foam
• Film door seal foam around edges
• Damaged door latch not closing fully
• Cracked prism housing
• Worn sprocket shaft seals

35mm Rangefinders:

• Back door seals
• Film counter window (if present)
• Viewfinder housing cracks
• Back pressure plate foam

Medium Format:

• Film back seals
• Dark slide slot felt
• Magazine light traps
• Bellows pinholes

Large Format:

• Bellows pinholes or cracks
• Film holder light traps
• Ground glass frame seals

Diagnosis

The most reliable test:

The position of fog on the film indicates the leak location. Fog at the top of frames (with camera held normally) means a leak in the bottom of the camera body, and vice versa.

Repair

Most light leaks are caused by deteriorated foam seals. Replacing them is straightforward:

Materials:

• Foam seal kit (camera-specific or generic light seal foam sheets)
• Thin wooden pick or plastic spudger
• Isopropyl alcohol or naphtha
• Cotton swabs

Process:

Shutter Problems

Slow Speeds Inaccurate

Symptoms:

• Overexposed frames, especially in low light (when slow speeds are used)
• Slow speeds sound wrong—too long or hesitant
• Speeds may be inconsistent shot to shot

Cause: Lubricant on the shutter mechanism has thickened over time. This affects slow speeds first because they rely on a mechanical delay mechanism (escapement).

Diagnosis:

• Fire the shutter at 1 second. Time it. Should be exactly 1 second.
• Fire at 1/2, 1/4, 1/8. Each should be half the previous.
• If slow speeds are obviously too long, the shutter needs service.

Note: Fast speeds (1/500, 1/1000) often remain accurate when slow speeds fail, because they rely on spring tension rather than the escapement.

Repair: This requires professional cleaning, lubrication, and adjustment (CLA). Not a DIY repair for most shooters.

Shutter Capping

Symptoms:

• Part of the frame is unexposed (black on negatives)
• The unexposed area is consistent—usually at one edge
• Worse at faster shutter speeds
• May be absent at slower speeds

Cause: The shutter curtains (focal plane shutter) are not travelling at the correct speed. One curtain catches up to the other, blocking light before the film is fully exposed. Often caused by:

• Worn shutter curtain ribbons
• Sticky or slow curtain travel
• Spring tension imbalance

Diagnosis:

• Fire at 1/1000 or fastest speed. Examine the frame for uneven exposure.
• If part of the frame is dark, the shutter needs service.

Repair: Professional service required. May need curtain replacement or tension adjustment.

Shutter Stuck Open or Closed

Symptoms:

• Shutter won't fire at all
• Shutter fires but stays open (bulb-like behaviour)
• Mirror locks up (SLRs)

Causes:

• Dead battery (if electronically controlled)
• Mechanical jam
• Broken spring
• Mirror box malfunction (SLRs)

First checks:

• Replace battery with fresh one
• Check battery contacts for corrosion
• Try mechanical speeds if camera has them (often B and sometimes one speed like 1/60)

If checks fail: Professional repair required.

Testing Shutter Accuracy

For precise testing:

Phone app method: Some camera apps can analyse shutter sound to estimate speed. Useful for rough checks.

Shutter tester devices: Dedicated testers measure actual shutter speed precisely. Available for purchase or at camera repair shops.

DIY methods: Point camera at a flickering light source with known frequency (some monitors at 60Hz). Different shutter speeds will show different numbers of flicker bands. Complex to interpret but can reveal problems.

Meter Problems

Dead Meter

Symptoms:

• No meter needle movement (match-needle cameras)
• No LED indicators (LED cameras)
• Exposure readout blank or unchanging

Causes:

• Dead battery (most common)
• Wrong battery type
• Corroded battery contacts
• Damaged meter circuit

Solutions:

Inaccurate Meter

Symptoms:

• Consistent over or underexposure
• Exposure varies with scene (meter misreads high/low contrast)

Causes:

• Wrong battery voltage (see above)
• Meter calibration drift
• Damaged metering cell
• Incorrect ISO setting (check the obvious first)

Solutions:

• Verify ISO setting
• Check battery type and voltage
• Compare with a known-accurate meter or phone app
• If consistently off by a set amount, adjust ISO compensation (set ISO 80 instead of 100 for 1/3 stop more exposure)
• Significant calibration errors need professional adjustment

Working Without a Meter

If your meter fails, you can still shoot:

Sunny 16 rule: In bright sun, set aperture to f/16 and shutter speed to 1/ISO. For ISO 400: f/16 at 1/400 (use 1/500).

Condition adjustments:

• Bright sun: f/16
• Slight overcast: f/11
• Overcast: f/8
• Heavy overcast: f/5.6
• Open shade: f/5.6
• Deep shade: f/4

Phone meter apps: Many smartphone apps provide reasonably accurate light metering. Use as backup when your camera meter fails.

Focus Problems

SLR: Viewfinder Focus Doesn't Match Film

Symptoms:

• Focus appears sharp in viewfinder but images are soft
• Images are consistently front-focused or back-focused
• Problem affects all lenses

Causes:

• Mirror position incorrect (misaligned or sagging)
• Focusing screen position incorrect
• Viewfinder optics damaged

Diagnosis: Test at wide apertures where focus is critical. Shoot a ruler at 45 degrees, focusing on a specific mark. If the sharp zone is in front of or behind your focus point, the camera needs adjustment.

Repair: Mirror and screen adjustments require professional service with calibration equipment.

Rangefinder: Images Not Sharp Where Focused

Symptoms:

• Rangefinder patch aligns but focus is off
• Problem may be consistent (always front or back) or erratic

Causes:

• Rangefinder out of adjustment (vertical or horizontal)
• Rangefinder cam worn (specific lenses)
• Mechanical damage to rangefinder linkage

Diagnosis:

• Test at close range with wide aperture where focus errors are most visible
• Try multiple lenses if available—if only one lens is affected, the lens cam may be the issue

Repair: Rangefinder calibration requires specialised tools and training. Professional service recommended, though DIY is possible with guides for some cameras (Leica, Canon, etc.).

Medium/Large Format: Ground Glass Focus

Symptoms:

• Sharp on ground glass, soft on film
• Focus plane appears tilted

Causes:

• Ground glass not at correct distance from film plane
• Ground glass shims missing or wrong
• Film holder seated incorrectly
• Film not flat in holder

Diagnosis: Use a ground glass focusing loupe to verify critical sharpness. Compare multiple film holders—if one holder consistently produces soft images, the holder is the problem.

Film Advance Problems

Overlapping Frames

Symptoms:

• Frames overlap each other
• Spacing between frames is inconsistent
• Frame numbers don't align with perforations

Causes:

• Sprocket drive slipping (35mm)
• Film not seated on take-up spool correctly
• Spacing mechanism worn (medium format)

Solutions:

• Verify film is properly engaged with sprockets
• Check take-up spool tension
• Medium format: verify backing paper is threaded correctly
• May need professional service if persistent

Film Not Advancing

Symptoms:

• Rewind knob doesn't rotate when advancing (35mm)
• Counter doesn't advance
• Entire roll comes back with same frame repeated

Causes:

• Film not caught by take-up spool
• Leader pulled out of cassette
• Sprockets not engaging

Prevention:

• After loading, verify the rewind knob rotates when you advance
• Watch for leader fully engaged on take-up spool
• Close back carefully without disturbing film

Rewind Failures

Symptoms:

• Rewind crank turns freely without tension
• Film tears inside camera
• Back opened with film not fully rewound

Causes:

• Rewind release button not engaged
• Film torn from cassette spool
• Mechanical damage

Solutions:

• Always press and hold the rewind release button while rewinding
• If film tears: in complete darkness, open back and manually roll film into cassette
• Don't force the rewind mechanism

Mirror and Mechanism Issues (SLRs)

Mirror Stuck Up

Symptoms:

• Viewfinder black
• Mirror remains in up position
• Camera may or may not fire

Causes:

• Mirror box jam
• Self-timer engaged (on some cameras)
• Mechanical failure
• Mirror bumper foam deteriorated and sticky

Solutions:

• Check if self-timer is engaged—trip it
• Try firing shutter at different speeds
• Replace mirror bumper foam if accessible and sticky
• If mechanically jammed, professional service needed

Mirror Damper Failure

Symptoms:

• Excessive mirror slap vibration
• Loud "clack" sound when firing
• Potential for blurred images at medium shutter speeds (1/30-1/125)

Causes:

• Mirror damper foam deteriorated
• Damper mechanism worn

Repair: Mirror damper foam replacement is straightforward and similar to light seal replacement. Use appropriate-thickness foam.

Slow Mirror Return

Symptoms:

• Viewfinder takes a moment to clear after exposure
• Frame rate reduced
• Occasional partial blackout in viewfinder

Causes:

• Mirror mechanism sluggish
• Lubricant deteriorated
• Spring tension reduced

Repair: Professional CLA (clean, lubricate, adjust) required.

Lens Problems

Aperture Not Stopping Down

Symptoms:

• Correct exposure at one aperture, wrong at others
• All images shot at maximum aperture regardless of setting
• Depth of field doesn't change when it should

Causes:

• Aperture lever/pin not engaging with camera body
• Oily aperture blades
• Mechanical damage to aperture mechanism

Diagnosis: Remove lens, look through rear while moving aperture ring. Blades should move smoothly. If they stick or don't move, the lens needs service.

Repair: Aperture cleaning requires lens disassembly—professional service for most users, though some repair guides exist for common lenses.

Sticky Aperture Blades

Symptoms:

• Aperture moves slowly or inconsistently
• Blades don't fully open or close
• Oil visible on blade surfaces when viewed through lens

Causes:

• Lubricant migrated onto aperture blades
• More common in hot climates or older lenses

Repair: Requires disassembly and cleaning of blades with solvent. Professional service recommended—aperture blade reassembly requires precision.

Fungus

Symptoms:

• Visible filaments or web-like patterns inside lens elements
• Patterns may look organic (branching, spreading)
• Reduced contrast, especially in backlit situations
• Often appears on front or rear element surfaces

Causes:

• Storage in humid conditions
• Fungus spores present in air grew in moist, dark environment
• Once established, can etch glass permanently

Prevention:

• Store lenses in dry environment (below 60% humidity)
• Use silica gel in camera bags
• Avoid airtight containers that trap moisture
• Occasionally expose lenses to sunlight (UV kills fungus)

Repair: Fungus cleaning requires disassembly. If fungus has etched the glass coating, the damage is permanent. Early-stage fungus can be cleaned; advanced fungus may require element replacement.

Haze and Cleaning Marks

Symptoms:

• Overall softness without visible spots
• Reduced contrast, especially backlit
• Visible swirl patterns when viewed at angle

Causes:

• Outgassing of internal lubricants onto elements (haze)
• Improper cleaning leaving residue or micro-scratches
• Coating damage

Solutions:

• Professional cleaning for internal haze
• External haze: careful cleaning with proper lens cleaner
• Coating damage is permanent

Element Separation (Balsam Failure)

Symptoms:

• Visible bubbles or cloudy areas in lens
• Rainbow patterns at certain angles
• Areas that look like the elements are lifting apart

Causes:

• Cement (Canada balsam or modern UV cement) deteriorated
• Heat damage accelerates failure
• Age

Repair: Element re-cementing is specialist work. Often not cost-effective except for valuable lenses. May be left alone if not severely affecting image quality.

When to DIY vs Professional Service

DIY-Friendly Repairs

Basic repair toolkit: small Phillips and flathead screwdrivers, rubber grip pad (for stuck filters/rings), lens cleaning supplies, light seal foam kit, coin-cell batteries. Total: ~£20-30.

Professional Service Recommended

Testing a Camera Before Purchase

Before buying a used camera:

If possible: Run a test roll before committing to the camera.

Summary

• Light leaks are usually repairable with foam seal replacement—a straightforward DIY task
• Shutter problems often require professional service, especially speed adjustment
• Meter issues are often battery-related—check the obvious first
• Focus problems indicate misalignment requiring professional calibration
• Film advance issues may be simple (loading error) or complex (mechanical failure)
• Lens problems vary: external cleaning is simple, internal work needs professionals
• Know your limits: some repairs are approachable with patience; others require special tools and expertise

Old cameras can be reliable workhorses with proper maintenance. Many problems develop gradually and can be caught early by periodically running test rolls and knowing what to look for.