Cleaning the back element of my 70-200L IS

So...I was pretty sweaty at my last wedding (95 in the shade and humid)...and while switching bodies, I think I must have dripped some sweat on the back element of my 70-200.

So the 70-200 back element is pretty deep inside of the mount, and I am not exactly sure of how to go about cleaning it.

I have read through a lot of the postings on cleaning, but most of them have dealt with the front element (or a speck on the inside of the FE).

Can anyone comment on cleaning the rear element? Is this a spot where the "lens pen" is my best option? It seems like that would be the way to go, but I would be curious to hear someone else's opinion....particularl​y if you have cleaned the RE on this lens before.

Thanks in advance.
Chris

just use a microfiber cloth on it...I use that for my 70-200 f/4L which also has its rear element pretty deep in the mount

I'd go with the standard methods. If you do a search you'll find a bunch of recent lens cleaning posts. If you don't think you can squeeze your fingertip down in there you can always use a qtip to get a lens tissue down there.

Microfiber cloth. I even use Q-tips for cleaning...

+1

I was at a small bird refuge a few weeks ago and while I was switching lenses I saw a mosquito fly into the mirror chamber just as I was about to seat the new lens. For some reason my brain could not get my hand to stop from moving the lens toward the camera. Fortunately the pest flew out just before the surfaces mated.

I don't want to even think about what could have happened when the mirror would have flown up for the next shot!