In the Library module, try Library -> Find All Missing Photos. I have LR 5, so I know it's in there. I don't know about LR 4.

I would consider myself as roughly fitting into that category. I have a couple main suggestions for you. Shoot a lot. Doesn't really matter what format it's in, what camera or lens you use, whatever. ...

I'm out of my element here, but... I did some testing and it seems that if you take the horizontal/vertical resolution of the camera's sensor, divide that by the Focal Plane Horizontal/Vertical ...

For reducing parallax, check out this helpful article. It has useful information on finding and using the no-parallax point on any lens, as do the links it includes at the bottom. Essentially, as you ...

Here is the tutorial: Watch on YouTube. Got it from this Flickr page. In a nutshell: Move all your icons off screen. Take a photo of your hand in front of the screen, making sure that you leave ...

I've wondered this myself, but never thought to ask. I'm not qualified to give a good answer, but it seems to me that, as Michael said, the bokeh is projected in the shape of the iris, which is ...

This is not a complete solution, but TinEye is a good tool for finding what other places use a certain image, even if it's a different size. Could be a good place to start.

It looks to me like the picture you linked to involves multiple mirrors. It seems to have been taken in some sort of studio with mirrored walls. I've attached a copy of the photo here with the ...

I made a few assumptions about your first question and did a quick test. I opened a DNG image in Lightroom 5 that I had never touched after import. It had the standard +25 sharpening applied to it ...

Wide-Angle lenses generally aren't recommended for portraits, since they distort features. Something around a 50mm lens is, for some people, the widest they are generally willing to go unless they ...

Moving parts inside the lens (especially if it has/uses autofocus or image stabilization) wear out over time. Glass can grow mold (or something similar). The better the build quality of a lens the ...

Anything is better than nothing (and at around $5 for a 3-pack it's definitely worth a try), but if you will use flash frequently, I would invest in a real, dedicated flash unit. Even a low-end flash ...

I think these are the only Nikon lenses that use plastic mounts: 18-55mm f/3.5-5.6 (II, VR, and G) 18-105mm f/3.5-5.6 18-135mm f/3.5-5.6 55-200mm f/4-5.6