[Ira]

Um, this doesn't make sense. Why would the WR work indoors and the non-WR not work indoors? The non-WR and WR 18-55s have the same aperture ratings, and the AL II version of the kit lens is (to my knowledge) optically identical to the WR.

The difference between these lenses is whether you would want to use them in a harsh outdoor environment... Makes no difference indoors unless you're taking pictures in the shower or after a fire sprinkler system has engaged.

I was waiting for the punchline.

[Douglas_of_Sweden]

Suggest WR 18-55mm because you can shoot indoors.
Non-wr 18-55 can't use indoors and it slow.

Are you living in a sauna?

[Pentaxor]

Are you living in a sauna?

pure classic.

[Arpe]

It's nice taking sports pictures out in the pouring rain, with a weatherproof cover over the lens and most of the camera. You can't avoid rain getting on the camera, and it doesn't matter, and I still have access to all the controls. So in my case it's more than just insurance.
eg-

[hcc]

... WR seems to be important.
If I'm concerned about the corrosion effects of humid/salty air, does it make it practically meaningless to have a K7 body with a non-WR lens?

There have been some very interesting posts, and I merely share an experience.

I have a K-7 and non-WR lenses. I would love to have a 18-250mm WR lens but there is none on the market.

When I shoot on the beach with some wind/breeze, sand, salt..., , I clean very regularly my lens. Especially the zoom lens that is most likely to be affected by humidity and salty air when you extend and retract the zoom. My Nokton 58 mm f1.4 is, on the other hand, very sturdy and required much less care.

Importantly I never change the lens when I am on the beach, or outdoor, in an unprotected area. I regard the lens change as possibly the most 'dangerous' time for the camera body. This is true for both WR and non-WER lenses.

So, for me, a WR camera and non-WR lenses are not meaningless! It may simply reflect the limited WR lens market, while the WR should not stop you to take care of your gears. As stated by an earlier post, the WR is an insurance.

Hope that the comment might assist ....

[Douglas_of_Sweden]

There have been some very interesting posts, and I merely share an experience.

I have a K-7 and non-WR lenses. I would love to have a 18-250mm WR lens but there is none on the market.

When I shoot on the beach with some wind/breeze, sand, salt..., , I clean very regularly my lens. Especially the zoom lens that is most likely to be affected by humidity and salty air when you extend and retract the zoom. My Nokton 58 mm f1.4 is, on the other hand, very sturdy and required much less care.

Importantly I never change the lens when I am on the beach, or outdoor, in an unprotected area. I regard the lens change as possibly the most 'dangerous' time for the camera body. This is true for both WR and non-WER lenses.

So, for me, a WR camera and non-WR lenses are not meaningless! It may simply reflect the limited WR lens market, while the WR should not stop you to take care of your gears. As stated by an earlier post, the WR is an insurance.

Hope that the comment might assist ....

You people are way too nervous about getting your cameras a little bit dirty.

First, do I have any right to say that?
Yes, because it is my profession to do research on how aerosol particles (you would call them dust) move in the atmosphere and interact with each other, clouds, solar radiation, climate and surfaces. Clearly I do not do this because we want to know what makes a camera or lens dirty, but it is the same physics, so I have a very good understanding of how "dirt" would end up on your sensor or inside your lens.

Really tiny particles, we are talking nanometer size, move similar to molecular diffusion, by a process called Brownian diffusion (one of Einsteins famoused 1905 papers was on this). These are so small that they change direction in a random manner because they collide with air molecules, which cause a diffusion like motion from high concentration towards low concentration. This motion goes towards any surface and would cause particles to deposite on your sensor even if you left the camera upside down. That is the bad news. The good news is that it is not these particles that you see as dust, they are just too small for that. They do not interact efficiently with light, and they have so little mass that you would have to wait for ages to see any effect of this process. They could probably have some sort of effect on tiny electronic components if they could get into them (this is why they take care to keep them out of electronics labs where they produce processors or similar stuff), but I would think the sensor is well enough protected by the filters that cover it.

Really large particles, from about a micrometer up to dust that can be seen by the naked eye, deposit due to gravitation. These particles are clearly a problem for the photographer if you get them on the sensor, less so in the lens (they will only degrade image quality very very marginally). This process is always directed downward. They are too heavy to efficiently follow turbulent motions, but high wind speed can lift them for a while. With the exception of dust storms, storms at sea etc you are fairly safe if you keep the camera mount downward while changing the lens. It is mainly if they land on the sensor, the focus plan, that you will get spots on the images. If these particles end up on the lens surfaces they are out of focus and have little effect. If you have many of them in a lens, they will degrade contrast, increase the risk for flare etc, but I have many old lenses with dust in and you would need a time machine and a factory brand new identical lens to compare with to see any difference in the images.

In between, in the range 1/10 to 1 micrometer, the deposition processes are less efficient. This is probably good for us, because in the lower end of this range you find the particles that interact most with light, but they are only efficiently removed from the atmosphere by rain, and I can't see how much of them could end up in your camera unless you leave it open in the rain, and then you would have much bigger problems. In the upper end of this range, there are deposition processes called interception and impaction, which basically mean that these particles follow the airflow, but when the airflow takes a sharp turn, like if it goes around a camera, the particles are too heavy to follow the air flow, so they may hit the object. Overall, I would think this process are of little concern for the sensor, because it is not in the direct air flow.

So what do I do?
I change lenses without worrying, I am more concerned with missing a good shot than with some dust going somewhere. I do have a healthy respect for sea spray because the salt and some organic acids in the sea spray are not good for electronics and can start corrosion, and the salt chrystals that can form when the sea spray dry are bad news for any fine mechanics. Of course I do not change lens in the middle of a storm on the North Atlantic, but it is way too fun too shoot on the ocean or on the beaches to not do it at all because of fear.
I do have a healthy respect for mineral dust, because like salt chrystals they are bad for fine mechanics. But still I change lens if I need to, of course not in the middle of a desert storm. I cary with me always gear to clean the camera, sensor and lenses and do so when needed (sensor) and regularly after every excursion (lenses, mirror, camera exterior).

After all, the whole point SLR cameras are to be able to change lenses. Not doing it is like having a car and not drive it because it could get dirty.

BTW, a super zoom like a 18-250 may pump more dust into its own interrior, where you cannot reach it easilly, than you ever get on the sensor (where you can clean it easilly) from changing between some primes. I'm not sure, but I suspect there would be difficulties with making a WR superzoom simply because it will be relocating lots of air that cannot go anywhere if the lens is air tight.

[bbluesman]

You people are way too nervous about getting your cameras a little bit dirty.

First, do I have any right to say that?
Yes, because it is my profession to do research on how aerosol particles (you would call them dust) move in the atmosphere and interact with each other, clouds, solar radiation, climate and surfaces. Clearly I do not do this because we want to know what makes a camera or lens dirty, but it is the same physics, so I have a very good understanding of how "dirt" would end up on your sensor or inside your lens.

.... of air that cannot go anywhere if the lens is air tight.

So should we start calling you Dusty?

[Douglas_of_Sweden]

So should we start calling you Dusty?

If you want to call me Dusty, that's fine. Nothing wrong with dust. Most materia on the earth has been dust many times during the eons. Stars grow out of interstellary dust. Of course I wish there was less dust on the floor at home and less dust on my slides when I scan them, but that's sort of unavoidable: 3rd thermodynamic principle.