foggy lens

The last 2 times I was out, the glass on the front of the lens fogged up. It happened half way through my shoot not at the beginning. Start was about sunrise. I had the lens shade on and am perplexed as to why it happens and how to prevent it in the future. I've seen ads for no fog wipes or spray stuff but I don't know if it works or if it's okay to use on lenses. I was told Nikon made some wipes but I can't find it online. Does anyone have experience with this issue or the products. Thanks in advance for any input.

Peter,

I would be leery of using any chemicals on a lens, or even a filter. You have no way of knowing if they will damage the coating.

I have found the best thing to use is a micro-fiber cloth. My most usual issue on a cold day is my breath condensing on the ground glass of my 4x5; pretty hard to focus when this happens. My micro-fiber cloth has come to the rescue more than once.

--P

I carry a microfiber lens cloth with me at all times (and a lens pen, which is great for dust). The fogging issue may simply be caused by a sudden increase in temperature, or if the sunlight is directly hitting your lens. I've found that wiping the glass off with the cloth helps, and I haven't had many "refogging" issues, but it's not as though the cloth works as a preventative measure ahead of time. If the interior glass fogs up there's not much you can do. When I was in Borneo, I'd go from an air conditioned room out into the jungle. The interior lens elements fogged up in that case and then everything took forever to normalize.

Max

Here's an item from Kevin Adams to prevent lens fogging. This item is especially helpful if you are doing night shots and/or star trails. I've got one & it works on those cold nights.

http://www.kadamsphoto.com/catalog/digital-after-dark-lensmuff-keeping-your-lens-p-85.html

It's a holder for chemical hand warmers that wraps around your lens, keeping it warm so it does not fog up.

Apparently a difference in temperature between the glass and the air somehow. Not sure, could be movement of some moister air running through and condensing? microfiber cloth sounds like a winner.