A visual defect sometimes observed in older photographic optics, the issue manifests as a cloudy or iridescent appearance within the lens element. This occurs when the adhesive, traditionally Canada balsam, used to cement lens elements together deteriorates over time. The degradation introduces air gaps, causing light to scatter and impacting image quality through reduced contrast and sharpness. The visible effect can range from subtle color fringing to distinct, web-like patterns or complete delamination.
Its presence significantly affects the value and performance of vintage lenses. Collectors and photographers should be aware of this issue, as it can severely degrade the optical quality. Historically, Canada balsam was prized for its optical properties and clarity, but its susceptibility to environmental factors like humidity and temperature fluctuations leads to this eventual breakdown. Recognizing the signs can prevent disappointment and inform restoration considerations.
