Spots on the inside of my glass

[Craig Brelsford]

During the trip to Inner Mongolia this month, I discovered water spots on the inside of the glass of my lens (Nikkor VR 600mm F/4G). Inner Mongolia was dry, but I spent five weeks during July and August in Sichuan and encountered much wet weather. Perhaps condensation occurred in the lens during the Sichuan trip and I only discovered the effects recently. I protect the lens with camouflage "skin" and a rain cover. I'll shoot for up to 20 minutes in a drizzle fully protected. I immediately seek shelter in anything more than a drizzle. When it was not raining in Sichuan it was often very humid. I remember at least one time when I emerged from a cool, dry, air-conditioned room into 30-degree C heat and 90 percent humidity. Condensation occurred on the glass that time, but my impression was that the condensation was limited to the outer surface of the glass.

The spots are hardly noticeable, and I doubt they have any effect on performance. Still, I'm worried.

Four questions:

1. What caused the water spots and how can I stop the spots from forming again?

2. How can I remove the spots?

3. What's your modus operandi when rain starts to fall? How long will you keep shooting in a drizzle?

4. Does high humidity ground you the way rain grounds you? Do you fear high humidity?

[John Chardine]

Hi Craig- Yes this is worrisome. I assumed with fixed-focus, internally-focussing lenses like this that the innards are sealed off from the outside. Having said this I guess there are some connections from the outside to the inside via the switches and wires and the focusing ring for example (unless it focusses by wire like the Canon 600 does). The lens is no doubt weather-proofed to guard against drizzle/rain getting in but if humid air somehow crept inside, you run the risk of it condensing inside under certain conditions. It's my hunch that this is what happened rather than drizzle/rain somehow seeping in.

With an expensive piece of kit like this personally I would eventually have to send in to Nikon for refurbishment.

I use a cheap plastic rain jacket for the lens and body, so rain just can't get in. Also have Lenscoat which must provide some extra protection. Yes I do fear humidity. In the winter here in Canada I routinely wrap cold gear up in plastic before I come indoors, thus trapping cold dry air in the bag. Then bring in the gear and let equilibrate over next few hours. I try to remember to remove my CF card before coming in the door, although you can always go outside again and open things up.

[Craig Brelsford]

John, hi, thanks for your response. Today I took the lens to Nikon's China headquarters, conveniently located here in Shanghai. After a long talk, the technicians and I decided to proceed this way. First, we're going to assume that the spots were a one-time occurrence, probably the result of taking the lens into hot, humid air after having stored it in a cool, dry, air-conditioned house. The Nikon guys explained to me that lenses are not made airtight and that humid air can get in. I mentioned your idea about the plastic bag. The technicians immediately nodded yes and said that no special bag was necessary. (Still, I'd like to know what type of plastic you use.)

If the spots were a one-time thing and can be prevented in the future, we further reasoned, then opening up the lens and cleaning the spots would be a bad idea. The spots are hardly visible anyway and will have no effect on performance. The technicians told me that opening up a lens and putting it back together again is a serious operation and risky. The risk is that the parts can get just slightly out of alignment. Of course, if I sent the lens back to Japan then the same people who assembled it in the first place presumably could put it back together again just right, but I'm not going to go that far just yet.

John, what do you think? Anybody else have anything to add?

[Norm Dulak]

Craig:

When I travel to places where moisture may be a problem, I do two things.

First, if precipitation is likely, I cover my equipment with a Storm Jacket Camera Cover (stormjacket.com).

After photographing, I put all of my equipment into a protective, restorative environment. I protect my equipment by putting it into a Ziploc Big Bag, which easily encloses my Nikon D300 camera with an attached 80-400mm VR lens and an SB-800 strobe. To remove any moisture taken up by my equipment I enclose Hydrostat 40g silica gel canisters in my bag with the equipment.

If the largest available Ziploc bags are not sufficient for your needs, put the canisters and your equipment into a larger plastic trash bag.

The canisters are heated in an oven prior to travel, to drive out moisture per instructions and then kept sealed in a Ziploc bag during travel. They are sold in many places, including at amazon.com: http://www.amazon.com/Silica-Dehumid...738090&sr=8-13.

I hope this will help you in the future.

Norm

[Doug Campbell]

probably the result of taking the lens into hot, humid air after having stored it in a cool, dry, air-conditioned house.

I don't buy this for a split second. Houston Texas is arguably one of the most humid areas in the country and friends and I frequently take lenses from air conditioned cars out into 90% + humidity and I have never seen a Nikon lens with condensation on the inside. Outside? Yes, big time. Seems to me the lens was/is improperly sealed.

[Craig Brelsford]

Wow, Doug, strong words. Thank you. Nikon told me yesterday that they have no way of testing the sealing. All they can do is examine the lens.

[John Chardine]

Craig, I just use a plastic garbage bag tied at the top to wrap the mark IV and 500. Low-tech but it works. I keep a couple in my camera bag all the time.

[Craig Brelsford]

Thanks, John. I will stuff some plastic garbage bags into my camera bag.