I'd be tempted not to try and clean a smudge that will have no effect on image quality, for the simple reason that the more times you do this the more chance there is of rubbing a piece of grit across the front of the lens and scratching it. If cleanliness is important, and to some degree it should be, get yourself a uv filter, then clean the smudge and apply the uv filter immediatly. I've cleaned the sensor on my EOS before, and I'm not squeamish about doing what needs to be done, but I also believe in minimising risk, particularly if you are not familiar with the processes involved. Once youve cleaned half a ton of assorted dirt, watermarks and other assorted gubbins off the front of the uv filter then you might be in a better position to look at contact cleaning the lens itself.

Yes, but be certain there are no chemicals in the grease/sweat of the smudge that might over time damage the surface of the coating.

JPL

Ive just my breath and my T-Shirt even on my L lenses when im out and about and nothing bad has happend. Other than that i use a bog standard lens cloth that you can get from the opticians.

Ditto. I'm afraid I've proved again and again that the quality of the kit is much better than my ability to use it.

In the OP's case I'd use isopropyl and a microfibre cloth. Failing that Fairy Liquid diluted and a tissue.

My own solution (links just quickly googled for example purposes):

Something like this (available at all good opticians): glasses cleaner

And some very soft lens/glasses cleaning cloths.

No need to spend loads of money or worry about damaging lenses by destroying any coatings. The type of solution used for cleaning glasses really is just very dilute washing up detergent and if you have two glass cleaning cloths, you can use one for wet dirt removal and the other for drying and polishing.

Some other advice:

http://www.howtocleanstuff.net/how-to-clean-eye-glas...

Importantly, never use dry facial (or other) tissue - their fibers are too coarse. It's mainly only at higher aperture values that specks of dust/dirt smudges really impact on image quality. You can experiment yourself by selecting aperture values above f10. Wide open, you will hardly notice.

Be ultra careful if ever you decide to clean the inside of the 'Through The Lens'/TTL camera viewfinder above the mirror. This is actually the focusing screen and is made of very soft plastic which scratches extremely easily. Just light fingernail pressure can permanently mark it. Not all focusing screens are user replaceable and cost upwards of £30 (plus any labour charges etc).

Try not to be too obsessive; all camera gear (in my view) is meant to be used and to an extent, abused. Any filters on the front of lenses can diminish image quality if not of pro standard. I think they can be good for certain environments but they can trap dust between the lens and the filter so can be a pain. Fitting a lens hood is a good way to protect lenses from scratching.

Many thanks for that. It makes a very interesting read and I have gained a few useful tips from those links.

Most greatly appreciated.

In reply to a post by SPOOKish:

My own solution (links just quickly googled for example purposes):

Something like this (available at all good opticians): glasses cleaner

And some very soft lens/glasses cleaning cloths.

No need to spend loads of money or worry about damaging lenses by destroying any coatings. The type of solution used for cleaning glasses really is just very dilute washing up detergent and if you have two glass cleaning cloths, you can use one for wet dirt removal and the other for drying and polishing.

Some other advice:

http://www.howtocleanstuff.net/how-to-clean-eye-glas...

Importantly, never use dry facial (or other) tissue - their fibers are too coarse. It's mainly only at higher aperture values that specks of dust/dirt smudges really impact on image quality. You can experiment yourself by selecting aperture values above f10. Wide open, you will hardly notice.

Be ultra careful if ever you decide to clean the inside of the 'Through The Lens'/TTL camera viewfinder above the mirror. This is actually the focusing screen and is made of very soft plastic which scratches extremely easily. Just light fingernail pressure can permanently mark it. Not all focusing screens are user replaceable and cost upwards of £30 (plus any labour charges etc).

Try not to be too obsessive; all camera gear (in my view) is meant to be used and to an extent, abused. Any filters on the front of lenses can diminish image quality if not of pro standard. I think they can be good for certain environments but they can trap dust between the lens and the filter so can be a pain. Fitting a lens hood is a good way to protect lenses from scratching.

You welcome. Glad you found it useful.

By far the best investment I have made in photo gear in recent years was purchasing a Lenspen - http://www.lenspen.com/?resultType=category&params=9...

http://www.amazon.co.uk/Lenspen-LP-1-Original/dp/B00...

Peanuts to buy, lasts for years and totally safe to use. Oh yeah, it just darn works better and quicker than ANY other method and I've tried them all over the last 40+ years. I have yet to see any other method that is quicker or more efficient. Use them on my Leica lenses with no trepidation whatsoever so cannot speak higher about the LensPen than that.