| Author |
Message |
    
Steve_s
Tinkerer
Username: Steve_s
Post Number: 43
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 30, 2007 - 02:22 am: | 
|
Due to damp I have to keep my cameras and lenses in plastic bags when not actually in use, with silica gel as a dessicant. This can keep the relative humidity down to 25% or less for months at a time, and if the volume is small it can go to less than 5%. Anything containing wood or genuine leather I keep separately at 50 - 60% RH, but this needs frequent monitoring.
According to the fungus prevention page on the Carl Zeiss site http://www.zeiss.com/C12567A8003B58B9/Contents-Frame/3CFD45E4A65DEC10C1257100005 6AC85 a RH below 30% is "dangerous for the instrument", though they do not say why. Does anyone know what could be damaged? All I can thing of is possibly shutter curtains, or maybe some varieties of glue. It would be a shame to keep the mushrooms at bay, only to cause some other dire problem! The same Carl Zeiss page reckons it is OK to store at up to 50°C as a means of reducing relative humidity, which I would have thought much more likely to cause problems.
Any ideas? |
Rick_oleson
Tinkerer
Username: Rick_oleson
Post Number: 315
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, June 30, 2007 - 06:57 pm: |
|
I can't think of anything that would harm a camera or lens in being too dry, though it might affect the lubricants or something. While there are things that don't want to "dry out", the moisture involved is seldom actually water so it is not likely to be helped by higher humidity. Like you, I would think that 50C storage would add to the problems in addition to giving you the low humidity that they had just finished warning against... in particular, the high temperature will soften the grease and increase the chances of oils migrating into the diaphragm and fogging onto the inner lens elements. I think the risk of your getting too dry is slight, I would keep doing what you're doing. If you were NOT controlling the humidity with dessicants, I would advise against the sealed bag as it tends to protect the fungus from the perils of fresh air circulation. |
Steve_s
Tinkerer
Username: Steve_s
Post Number: 44
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, July 01, 2007 - 06:34 am: |
|
I would expect that anything that might be affected would have to be organic, and the only organic thing I can think of in a lens is Canadian balsam in cemented elements, which apparently is a resin from the bark of a tree. In any case, as far as I know this hasn't been used for many years, so Zeiss would hardly have considered it.
As for cameras, SLR curtains might be cotton, I suppose, and their coating is probably natural rubber, but I am doubtful whether either would be damaged by dryness.
I might try emailing Zeiss with the question, but I think the chances of it getting to anyone who would know the answer are pretty slim, so I'll keep on doing what I'm doing, but maybe in future I will let the RH creep up to 30 - 40% before I change the silica gel! |
Steve_roberts
Tinkerer
Username: Steve_roberts
Post Number: 4
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 31, 2007 - 02:33 am: |
|
I do much the same thing for exactly the same reasons, only I keep cameras in the airtight rectangular tubs that are intended for use in freezers. I think that of all the potential problems, mushrooms are the worst and I'll take my chances with any other issues. |
Alex
Tinkerer
Username: Alex
Post Number: 39
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 31, 2007 - 03:27 am: |
|
I too use plastic tubs with snap-on lids, bought from a hardware store, for storing cameras and lenses. I put one or two bags of silica gel in each box, and check them regularly to see if the gel bags need drying off by looking at the desiccant colour. I hadn't thought to check the humidity level using a hygrometer. Is this worth doing? |
Adrian
Tinkerer
Username: Adrian
Post Number: 69
Registered: 08-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, July 31, 2007 - 03:47 am: |
|
I believe that static electricity can become a problem in a very dry atmosphere, which I can certainly see causing problems in an electronic camera. Possibly automatic apertures might be at risk of a spark if this happens? That is a wild surmise, though!
Adrian |
Streetlife
Tinkerer
Username: Streetlife
Post Number: 16
Registered: 10-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, August 02, 2007 - 04:17 pm: |
|
Hi all. Good thread this.
So what’s the biggest culprit for inducing fungus growth. The Dark? The Humidity? or, The Lack of air flow? And does leaving a lens in sunlight help ward off the dreaded mushroom?
All the best
Scott. |
Steve_s
Tinkerer
Username: Steve_s
Post Number: 46
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 03, 2007 - 12:56 pm: |
|
Humidity is definitely the killer, but all three are better still! Hopefully, without the damp the other two won't matter.
Regarding Alex's question, I can thoroughly recommend "Humonitor" indicator cards. I obtained them here in the UK, but they are made in the USA by Multisorb Technologies (Tel 800-445-9890). They have six spots on them indicating humidities from 10% to 60%. They are very accurate according to my hygrometers. |
Flyingo
Tinkerer
Username: Flyingo
Post Number: 1
Registered: 08-2007
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, August 06, 2007 - 10:33 pm: |
|
Aloha everyone, I live right on the beach in Hawaii (yes, I know I'll get no sympathy..), should I take any "extra" precautionary steps to keep my gear dry? I have purchased quite a bit of silica gel desiccant and am in the process of getting all gear bags, lens cases and the like prepared for their time here, but I thought this would be a good place to ask if there is anything more I should do because of my close proximity to the sea air. Thanks in advance for your advice! - Mike O. |
Alex
Tinkerer
Username: Alex
Post Number: 40
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, August 07, 2007 - 01:11 pm: |
|
Steve, can you say what the pricing is? I found a UK web site for Multisorb, but there was no pricing information that I could see. They look the business.
Incidentally, 7dayshop (for UK folks) have been selling off silica gel bags for photo use fairly cheaply, so I've just taken delivery of fifty of them, for less than GBP 5. |
Steve_s
Tinkerer
Username: Steve_s
Post Number: 49
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, August 08, 2007 - 11:55 pm: |
|
Alex, The firm I got them from had a minimum order quantity of 100, and I think the price was about £35, but as I only wanted a few they sent them gratis. I'd suggest you contact Multisorb directly and ask where you can get a small quantity (I hadn't realised they had a UK presence). If you don't come up with anything, maybe we could organise a joint order (with any others in the UK that may be interested). I could use a few more myself! |
Steve_s
Tinkerer
Username: Steve_s
Post Number: 59
Registered: 07-2006
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, September 22, 2007 - 01:31 am: |
|
I finally got around to contacting Zeiss to ask why relative humidity below 30% is "dangerous for the instrument". It looks as though Rick's first guess was right!
Their reply was: "When you store photographic instruments below 30% humidity for a longer time, the greases will degenerate or their substances of content will diffuse. So if you want to use these instruments, they should be stored above 30% humidity." I'm not too sure what this means. Are they suggesting that in the absence of any significant water vapour pressure, the lubricant will take its place and condense on the lens?
I still think that the greases would degenerate a darn sight quicker stored at temperatures near 50 degrees centigrade which was one of their options! I reckon I will have to live with the risk for the time being as long as it keeps the fungus away. |
