Mold is not nice

[george013]

Even ifr i do say so myself this thread has taken an interesting turn. But to clarify one point...

My problem is not so much humidity during storage as it is humidity during shooting. I'm out there having fun, the sun comes out instrant sauna as the moisture in the earth and on the plants is vaporized.

I already thought so. I've no solution. But does your lcd looks like Graham's? For I don't think that's mold from insight the camera but more a leaking lcd cover, which is over the lcd. He's using his left thumb a lot.

Off topic. I looked at the specs of the Sony a77. It has a mirror that doesn't move?? That's new to me.

George

[JBW]

I already thought so. I've no solution. But does your lcd looks like Graham's? For I don't think that's mold from insight the camera but more a leaking lcd cover, which is over the lcd. He's using his left thumb a lot.

Off topic. I looked at the specs of the Sony a77. It has a mirror that doesn't move?? That's new to me.

George

There are a few Sony Cameras with translucent mirrors. Scroll down a bit in this link and it's explained.

[DanK]

My problem is not so much humidity during storage as it is humidity during shooting. I'm out there having fun, the sun comes out instrant sauna as the moisture in the earth and on the plants is vaporized.

Ah. Many of us indeed missed the boat.

If you are quick enough, you could wrap the gear and wait a bit for it to warm up in the sun.

Even with the situation you mention, I would still store the gear in a sealed container with desiccants, and I would dehydrate the desiccant often. (In the Adirondacks, which is humid but I would guess far less humid than where you are, the silica gel is partially hydrated within a week or two.) That way, even if gear gets damp during the day, it will dry out when stored, making it harder for any mold to grow.

[Stagecoach]

But does your lcd looks like Graham's?

For I don't think that's mold from insight the camera but more a leaking lcd cover, which is over the lcd. He's using his left thumb a lot.

It's identical mould growth patterns that are also in some lenses I have and on this camera is just starting to be visible on the mirror also.

As for the area of missing paint I put this down primarily to sweat, oil and salt from my face getting behind the buttons and then working away to corrode and then lift the paint and in the process has finally affected the seal of the left side.

The area where it is most apparent is around the two buttons that I use the least on that row

[Manfred M]

Buttom ax is the temperature, vertical ax is the amount of water in the air. The red curved lines are the different relative humidity percentages. If you know the temperature and the relative humidity then you can read the amount of water in the air and the temperature at which the condensation starts, that's the 100% line.

Practical.
Inside the house there is a temperature of 20C and a humidity of 70%. Seek the line crossing between 20C and 70%. To the right you can read the amount of water in the air, 0.010, and to the left at the 100% line you can read the condensation temperature, something as 14C.
Simply you could say that if the camera was outside in a temperature lower as 14C and you would enter that room, you will experience condensation on the camera.
The figures are based on an easy reading of the diagram.

George

George I was being a bit pedantic as my response was to Ted's comments, just because Ted tends to do this. He generally will bring up points that to some will appear to be fairly minor. My intent was to do this as well.

His example about the watch, which is what I was responding to, dealt with condensation with the condensate mixing with the lubricants in the watch. A psychometric chart is based on evapouration, not condensation. Wet bulb / dry bulb measurements are how relative humidity is determined. A wick on the wet bulb thermometer is saturated with distilled water and the air is set to flow around the wicked bulb of the thermometer; traditionally this is done by whirling the thermometer around for about one minute. Some devices are equipped with a small fan to accomplish the same purpose. The energy required to evapourate the water on the wick lowers the temperature and the thermometer reads that. By using the chart's wet bulb and dry bulb readings, we can determine the relative humidity.

Conversely, if we know the relative humidity or dry bulb temperature, we can also use the chart to infer the wet bulb temperature. The question is: Is the wet bulb temperature identical to the dew point, i.e. the temperature where gaseous water will condense. The answer is NO, the dew point is slightly below the wet bulb temperature, as we should not get any evapouration while the water is condensing. The only condition where they are exactly equal is for 100% relative humidity; at this point the wet bulb and dry bulb reading will be identical.

That being said, given the scale of the graphs, what you write is approximately correct; the wet bulb temperature is approximately the same as the dew point.

If you look at the dew point chart I added, it is more or less identical to the psychometric chart. On the psychometric chart, the temperature scale is linear and the relative humidity scale is non-linear. On the dew point chart, the temperature and dew point axes are non-linear, but the relative humidity is shown as a straight line.

[Manfred M]

Off topic. I looked at the specs of the Sony a77. It has a mirror that doesn't move?? That's new to me.

Sony has not built a DSLR in quite some time. They switched to a fixed mirror design in their higher end cameras a number of years ago. If I remember correctly, this started in 2010 or 2011.

[Manfred M]

Even ifr i do say so myself this thread has taken an interesting turn. But to clarify one point...

My problem is not so much humidity during storage as it is humidity during shooting. I'm out there having fun, the sun comes out instrant sauna as the moisture in the earth and on the plants is vaporized.

These are separate but related issues:

1. The relative humidity in the tropics can be very high; approaching 100% for considerable periods. These conditions promote mould growth.

2. High humidity means that condensation will occur when the camera / lens body temperature are lower than the dew point for the relative humidity conditions. I've run into this quite a number of times when traveling in the tropics. Stepping out of a cooler interior relative to exterior temperature / humidity conditions, whether that be a place we were staying or vehicle we were traveling in.

Until the camera and lenses get to the same temperature as the ambient conditions, your will get condensation. The only solution is to keep the equipment away from the warmer, moister air until the camera equipment gets to the ambient temperature of where you are shooting. Yes, air conditioning will make this worse, but it is not exclusive to an air conditioned environment. It can occur any time that you move the equipment from a cooler to a warmer and more humid environment; even when no air conditioning is involved.

The previously recommended bagging the gear until the temperature equalizes is the ONLY way to prevent condensation on / in the camera equipment.

[Arjung]

Even ifr i do say so myself this thread has taken an interesting turn. But to clarify one point...

My problem is not so much humidity during storage as it is humidity during shooting. I'm out there having fun, the sun comes out instrant sauna as the moisture in the earth and on the plants is vaporized.

Brian,
I live in a hot humid tropical environment and did have problems with my gear.

I invested in a humidity controlled cabinet 2 yrs ago and have not had a problem since

[JBW]

Brian,
I live in a hot humid tropical environment and did have problems with my gear.

I invested in a humidity controlled cabinet 2 yrs ago and have not had a problem since

I'll look into it

[george013]

Brian,
I live in a hot humid tropical environment and did have problems with my gear.

I invested in a humidity controlled cabinet 2 yrs ago and have not had a problem since

I don't live in a humid environment, well unless it's raining.
How do you use it practical? Do you also set the temperature? For my first thought was that if that temperature is lower as outside the cabinet you will get condensation immediately when you take out your gear.

George

[Arjung]

I don't live in a humid environment, well unless it's raining.
How do you use it practical? Do you also set the temperature? For my first thought was that if that temperature is lower as outside the cabinet you will get condensation immediately when you take out your gear.

George

George,
My camera gear lies in there unless I am using it.
The cabinet only allows you to set the humidity. Their is not much difference between the temperature inside & outside the cabinet

[george013]

George,
My camera gear lies in there unless I am using it.
The cabinet only allows you to set the humidity. Their is not much difference between the temperature inside & outside the cabinet

I see. It takes the temperature of the room.

George

[Manfred M]

I see. It takes the temperature of the room.

George

Not quite George; it removes the humidity from the room.

I live in a climate where we use a room dehumidifier to reduce the humidity in areas of the house in the summers. Mechanically it is really a small air conditioner that is vented back into the room, so it does warm things up too from the waste heat. Air conditioners are vented to the outside to remove heat from the house. We have one of those hooked into the air ducts in the house as well, but only run it on the really hot days; i.e. central cooling.

In the winter, the air here gets so dry that we use a central humidifier that is attached to our forced air furnace, to add humidity to the air. Knowing the dew point is important, as condensation will form on the windows (window glass, even when double glazed, argon filled and with a low emissivity coating is still a relatively poor insulator). Condensation can form and will damage the paint work on the window trim.

[xpatUSA]

"There is not much difference between the temperature inside & outside the [controlled humidity] cabinet"

A dehumidifier reheats the air after cooling it below the dew-point to extract the moisture. That is why there is little difference in temperature.

1. A fan collects air from the surrounding area and pulls it into the dehumidifier.
2. As the air passes through, it comes into contact with the dehumidifier's cooled coils. These coils use condensation to pull moisture from the air. The collected moisture remains on the coils and drips into the dehumidifier's reservoir.
3. The dehumidifier reheats the air and exhausts it back into the room.

https://home.howstuffworks.com/dehumidifier1.htm

"the room" in this case being the cabinet internal space.

Unashamedly, I offer a psychrometric chart of the process:



I marked it up to include the heating part, state 2 to state 3.

Easy enough to understand, in spite of the claimed unsuitability of that chart in these matters.

[george013]

Not quite George; it removes the humidity from the room.

I live in a climate where we use a room dehumidifier to reduce the humidity in areas of the house in the summers. Mechanically it is really a small air conditioner that is vented back into the room, so it does warm things up too from the waste heat. Air conditioners are vented to the outside to remove heat from the house. We have one of those hooked into the air ducts in the house as well, but only run it on the really hot days; i.e. central cooling.

In the winter, the air here gets so dry that we use a central humidifier that is attached to our forced air furnace, to add humidity to the air. Knowing the dew point is important, as condensation will form on the windows (window glass, even when double glazed, argon filled and with a low emissivity coating is still a relatively poor insulator). Condensation can form and will damage the paint work on the window trim.

It removes humidity from inside the cabinet. When there's no additional source of heating in the cabinet, then the temperature in the cabinet will equals the temperature of the room, in time. That's good.

George

[xpatUSA]

It removes [water] from inside the cabinet. When there's no additional source of heating in the cabinet, then the temperature in the cabinet will equal the temperature of the room, in time. That's good.

George

Spot on, George. Looks like we were typing at the same time . .

[Arjung]

George, Manfred, Ted,

I think there is some confusion so let me clarify. Humidity controlled cabinets and humidifiers / dehumidifiers are 2 different things.

Humidifiers / dehumidifiers control the humidity levels for the entire room.

Humidity controlled cabinets only control the humidity inside the cabinet.

[Manfred M]

George, Manfred, Ted,

I think there is some confusion so let me clarify. Humidity controlled cabinets and humidifiers / dehumidifiers are 2 different things.

Humidifiers / dehumidifiers control the humidity levels for the entire room.

Humidity controlled cabinets only control the humidity inside the cabinet.

Understood, but the principles are identical. Humidity is controlled by some means; usually mechanical, so that the humidity is within per-determined limits in that space.

Humidity control is not only used to remove humidity; in some environments, humidity is added when the relative humidity is too low.