Another thing nice about using lower iso's & smaller f stops is long shutter speeds (reason for the tripod). Slower shutter speeds means that if someone walks through the scene they will not show up in the photo. Moving subjects are not in the scene long enough to register on the sensor.

As others have said, it is a very good lens. Before I switched from Canon 5D to Pentax I had the L lens. At the time I wasn't sure if I wanted the Canon L or the Sigma 105 F2.8 Macro. Both have IS. I ordered them both and ended up keeping the Canon. Below is a link to what I thought of both lens. This isn't a very good test because the photos were not the same and under the same conditions. I thought both were about equal in quality, but if hand holding I thought the Canon L had a better IS.

http://wingincamera.zenfolio.com/lens-test

I have never lost anything on a memory card. But just the same I usually only use 8 GB cards, sometimes a 16 GB, so if something does happen all my photos are not in one place. My raw files are only about 20 mb's each and I shoot very little video (use a actual video camera for that).

What a sweet old gal.

I use LR4 with only one problems. One time my catalog was corrupted, but my backup copy corrected it.
I have used the slideshow, print, and of course develop and the library. I do keep a list of all serial numbers of all programs installed. I just ordered LR5.

I hand spanked my kids less than my dad did me. My dad usually used his belt. And when we were warned about something that would result in a spanking there was no "counting to three" or something similar, we learned to listen. I know I deserved everyone, including things I didn't get caught doing.

Now me and my five brothers all grew up well adjusted, responsible adults and families of our own. We learned the value of working and taking care of each other.

Now, I once did threaten to sue my parents when I found out that I might have been traumatized when born because we were all circumcised. But it didn't seem to destroy me anymore than being spanked.

One other thing, all my wife brought with her was a Canon G9 point & shoot. She was in a tour group and things moved fairly quickly. One of the other members in the group was carrying a dSLR with multiple lens and found it too slow to try changing lens and carrying everything. He realized he spent so much time with the camera and not seeing the land. He ended up just using one lens so he could enjoy the experience more. If your by yourself you can slow down, not so much in a group.

I can't answer your question about filters, but thought you might be interested in seeing my wife's blog about her trip to Israel a year ago. She did a great job documenting the the trip. On the blog she is Suzette.
Here are two different url's in case one does not work.

http://israelsues.blogspot.com/
http://israelsues.blogspot.com/2013_03_01_archive.html

Oh come on, I am sure he would have purchased the necklace first before going into the Pub, right?

I love it, I had to copy to post on FB.

I use a DOF calculator on my cell phone. There are several to choose from, most are free.

When I was using a Canon 5Dc, my favorite lens was a Sigma 24-70 F2.8 (non OS). Later I picked up my only "L" lens, 70-200. Good glass is important with this camera. I had a few other lens, but these were the two I used the most. Purchased the Sigma new, the 70-200 used from Craig's list.
A good place to look for used lens is Keh's
http://www.keh.com/
They have a good warranty & exchange program.

Using it between two filters works. I just rubber band the coffee filter over the end of the lens. Works for any size lens.

I sometimes have a need to adjust white balance when shooting indoors in mix lighting situations. I use to use a gray card to set a custom white balance in camera even though I do shoot raw.
But then I heard about just using a plain old white coffee filter over the lens to set the white balance. It is so much easier to carry one in the bottom of my bag. If you google "coffee filter white balance" you will find lots of info. Here is one link below.

http://www.ppmag.com/web-exclusives/2008/11/product-comparison-white-balan-1.html

Some photos are fairly expensive too. How about $4, 338.500 for this one? (2011 prices)

(link removed for spamming)/photography-articles/3004-the-19-most-expensive-photographs-ever-sold