What would you recommend?

My lenses don't get that dirty!

I use a small blower and a soft lens brush to get most stuff off them. If they've got splash marks on them, then I use lens tissue and a drop or two of cleaning fluid ("lens cleaning fluid", or "eclipse", or something similar). Oh, and much of the time a small microfibre cloth is all it takes.

But that's all very old school of me -- quite literally, it's how I learned to do it over 30 years ago in high-school.

I too wonder how the modern crowd deal with this? Cris?

This is not going to help but, I've always been told the best way to clean a lens is not to let it get dirty.

One way is to keep a neutral filter attached. Filters being easier to replace than lenses.

My question is do digital SLR lenses allow keeping a filter attached?

The instructions of my L Series say to clean with a soft cotton cloth. I normally take that as meaning the bottom of my shirt.

Other than that I I just use a dry micfofibre cloth, I have some solution back at home, but I couldn't tell you what it is as I've had it so long.

I'm not one for using UV/protection filters either, as I don't shoot with the lens hood most of the time I find it causes loads of problems. I'm fully ensured and the excess is much less than the cost of a decent filter anyway.

Cheers

Cris

Yes, they do.

This is the old camera-shop method -- sell a customer a lens, and then add considerably to the bottom line by also selling them a cheap filter for an inflated price. Just like 95% pure profit "extended warranties" are what keep many automobile dealerships (as well as electronics shops) afloat.

The problem with filters can be summed up like this:

1. If you have a cheap lens, they're probably not worthwhile. Just take the risk on the lens, and replace it if you scratch it badly enough.

2. For expensive or rare lenses, some form of protection could be a good idea if you are a klutz like me. But if you cover that nice expensive coated glass with a filter, you're basically crippling it.

There are several problems with filters.

3. Being of non-zero thickness, they cannot help but distort the light passing through them. None of the other elements inside that expensive lens are flat planes for that very reason.

4. The filters the camera shop pushes on most folk, have poor or non existent anti-reflective coatings, so the light is going to bounce around a bit too much. This can be mostly overcome by buying really expensive filters, in the 100-200 currency unit range. But again.. at that price level, it's probably cheaper to just go without, and pay for repair in the unlikely event that you ever scratch the lens. And there's the much more real risk of scratching the out-front 100-200 currency unit filter.. doh!

5. Since the filter sits out at the end of the lens barrel, it attracts flare from any point light source in the vicinity. It also reflects, or blocks, some of the light that would be better allowed to reach the camera sensor.

I put moderately expensive filters on many of my lenses when new. Most of those have long since been removed, in favour of lens hoods. These provide fantastic physical protection for the lens, don't block any of the important light rays, and reduce flare, ghosting, and improve contrast. But they do make some lenses more unwieldly and more obvious.

I still carry a few filters, for when they are actually needed for their original purpose: UV for very hazy sunlight, and polarizers for wet/bright conditions where I may want the sky to look blue (instead of white), or want deeper saturation on foliage and the like.

Cheers

I put a filter on every one of my lenses, and I go for the pricier ones (B+W makes some nice ones; Nikon-branded filters are also very good) in order to avoid the problems that mlord describes.

I have a polarizing filter on a couple of my lenses and at least a UV filter on the rest. The only problem I've had is the colors being oversaturated in some 'spur of the moment' type shots indoors where I didn't have enough time to get enough light in the room. Other than that, no issues at all.

A polarizer is really a specialized thing. You only need it for particular things (darkening blue skies, seeing through reflective glass, etc.). Otherwise, I wouldn't want to take the brightness hit.

Thanks for all recommendations, guys. I am going to go with some soft cloth (I have few that came with my glasses) when needed, then.

For modern lenses I use a Lens Pens after going over it with a Camel Hair Brush and it works very well. The Lens Pen often leaves smears that you can then easily get rid of with just your breath and a dry microfiber cloth. If your lens is really dirty I would use a very small amount of liquid cleaner. A drop of Windex w/ammonia works well and gets things very clean. It won't take the coating off modern lenses- but I wouldn't try it with a very old lens.