i had heard about dry cabi..what is the purpose(prevent dust or moist?)?? is it a must to have??
The ambient relative humidity in SG (70-90%) is higher than the recommended environmental conditions of most manufacturers (see manual). Fungus "loves" such conditions: warm, humid, organic material (e.g. sweat, dust) and dark. So it's just a question of time till you'll get some fancy "development" inside your camera or lenses. If you don't like this you better store your equipment under conditions that are less welcoming to fungus, a lower RH of about 40-50%
Whether you use a simple dry box with silica gel or a electrical dry cabinet is up to you. Here is a nice article about the common types of dry cabinets. In addition, a dry cabinet also serves as a common storage for all gears (e.g. filter). Keeps it tidy.
No need to panic, get something within the next weeks after you got your cam and you are fine. Also, the best way to prevent fungus is using your gear and exposing it to sun.