The small one on the right was bought in Japan at Yodobashi Camera Store and is still accurate after 13 years. The one on the left is off by 15%. So I have stuck label on the dial that read +15% which means whatever is the reading, add 15 to it.
How often one needs to re-heat the silica gel depends on the Relative Humidity (RH) in the surroundings and how often you open the boxes.
During winters, an unopened box will stay within limits for about 4 – 5 weeks. Open it couple of times and it will stay within limits for couple of weeks.
During the monsoon season in Bengaluru, with outside RH% about 90%, open it once for taking the lens out and you have to reheat it.
After a shoot in the monsoons, clean and dry the equipment as soon as you finish. Lens coats and other covering often take some time to dry. Place them in the dry cabinet or the silica gel box immediately.
A bad place to store camera is in the camera bag or in a closet full of clothes.
Monsoon is a nice time to click pictures that are out of the ordinary. Stay dry, keep your equipment dry, and happy clicking.
5. Close the lid and the silica gel starts absorbing moisture in the box. When the silica gel turns light pink, it is saturated with moisture and no longer active. At this time, heat it on a pan over a slow flame or use a microwave. The moisture evaporates from the gel and it turns blue once again. Be careful the container and the gel will be hot.
6. Place the containers in an area where indirect light falls on it during day time. I keep a low wattage light lamp on during the night.
While this method relies on the observation of colour of the silica gel. Investing in a hygrometer helps in measuring relative humidity in the box. Keeping a hygrometer in the box will provide readings and takes guesswork out of the exercise.
3. Place your lenses with front cap and rear cap removed carefully in the box. Avoid placement where the front or rear of the lens can potentially knock against sides of the boxes. This is to keep the lens elements exposed to light. Close the caps and you are providing a dark place for fungus to grow.
4. Place a handful (around 200-300 gms) of desiccated silica gel in an open container or in a wrap that would allow silica gel to absorb moisture. Buy silica gel which is of indicating type. This is blue when it is ready to absorb moisture and turns a light pink when it has absorbed all the moisture and is saturated.
Camera gear protection in monsoons
We spend a lot of time, and money in acquiring gear that would help us in our photography journey.
While shooting in adverse conditions itself puts the gear through a rough pace. Storing the gear in places of high humidity like coastal regions, regions with heavy monsoons, or regions close to the equator is another problem.
Primary problem in these conditions is the growth of fungus inside the lens elements that not only degrade the lens coatings but lead to soft images as the fungus growth accelerates.
What makes fungus grow inside lenses is not exactly known. I am sure fungus cannot differentiate between a pro lens and a consumer lens. The primary attraction seems to be the coating on the lens which is made of organic elements.
Fungus thrives in places with high moisture content and darkness.
Do not worry yourself looking for a place with no fungus. The spores are everywhere and start growing when the conditions are right.
Eliminate moisture and darkness and you have protection from fungus growth.
Dry cabinets are one solution to the problem. These resemble mini refrigerators with a transparent front door. They create a dry environment in the cabinet, some models offer settings to control the humidity levels. These may or may not have a light bulb. These units need to be plugged into an electrical socket all through and may not be a good solution where there are frequent power outages.
Till about a few years ago it was difficult to procure dry cabinets in India. These units are fairly common in Japan and Singapore.
Other solution somewhat low cost and laborious is to use airtight boxes with moisture absorbing materials like desiccated silica gel.
The way this works is
1. Find a container that is transparent and large enough to fit your lens and cameras. For a beginner kit of a small body and a small lens, a bread box would suffice. A larger box occupied with small gear will have empty spaces with air that needs to have moisture removed. Just right size is good.
2. Place a bubble wrap or glazed paper on the bottom of the box (anything that is will not absorb moisture in large quantities). This is not necessary and only meant to prevent lens rolling and knocking against each other as you move the box around.
The reading in the figure above was the relative humidity during monsoon in the room. It is about 88% and overnight with silica gel and the hygrometer in the box the humidity dropped to around 34%
How much humidity is good is debatable. Too dry and the lubricants in the moving parts of the lenses will dry up.
Somewhere between 30% - 50% seems to be ok. I had no issues within this range.
Not all hygrometers are accurate and need to be calibrated using the salt test. Google “How to calibrate hygrometer salt test”