Can camera lenses be damaged by storing them in very low humidity?
Asked 1/13/2024
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I set up a DIY dry box using an airtight container and silica gel for lens storage. It quickly dropped the humidity inside to about 10% RH. I've often seen recommendations to store lenses around 40% RH, so I'm wondering whether keeping lenses that dry could cause damage. Is 10% relative humidity safe for long-term lens storage, or should I raise it closer to 30–40%?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
2y ago
2 Answers
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According to Zeiss, humidity levels below 30% is "dangerous for the instrument". About the only thing I can think of that might be affected by very low humidity is the adhesives used in bonding lens elements; most things in a lens are much more affected by oxidation than humidity (lubricants, plastics,rubbers, etc). But there is probably more involved that I don't know about... So I would take Zeiss's statement as fact, at least regarding some lenses.
How can fungus be avoided?
Reduce the relative humidity to less than 60% (never under 30% as it is dangerous for the instrument) by storing:
Zeiss also states that for humidity to be problem it needs to be over 70%, for more than three days, with no/very little air movement, and darkness. Your DIY box is probably creating two out of three of those conditions. Whereas those are not conditions that typically exist in most environmentally conditioned homes. If those conditions do not exist in your home, then I would have to say that the DIY dry box may be doing more harm than good...especially since it's not really needed.
Relative humidity of at least 70% (more than 3 days)
No or little airflow
Darkness
Originally by user70370. Source · Licensed CC BY-SA 4.0
user70370
2y ago
0
Generated from our catalog & community — verify before relying on it.
Very low humidity may not be ideal for long-term lens storage. Based on the community answer, Zeiss advises keeping storage humidity below 60% to prevent fungus, but not under 30%, calling that potentially dangerous for the instrument. One possible concern is that extremely dry conditions could affect materials inside the lens such as adhesives; other components may also have manufacturer-specific limits.
A practical takeaway is that you usually want storage dry enough to avoid fungus, but not aggressively dry. Around 30–40% RH is a safer target than 10% RH if you can control it.
Also, high humidity becomes most problematic when it is sustained above roughly 70% with little airflow and darkness. So your dry box is useful, but you may want to reduce the amount of silica gel or monitor humidity so it doesn’t stay extremely low.
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AI2y ago
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