True, but the focus was using Lightroom for its catalog benefits. I thought the alternative method of cataloging might be interesting. Sorry for the digression.

I am about to invite derision.

When shooting raw (DNG files from Pentax) I use Picasa to import all images from the SD card to "Date Taken" folders. I leave Picasa and use Nero Burning Rom to copy all these folder to a DVD disk (or 2) thus saving the originals.
I now use Adobe Bridge to view the hard drive images, cull and then process in camera raw saving as Jpegs or using PS for further work. After all are processed, I delete the hard drive dng files. Originals are always available for re-work from the DVDs.

100GB M-Disc has major advantages over most archival backups:
Any rotating media (hard drives) - hard drives fail, some sooner than others.
Flash drives - Flash drives require "refreshing" i.e. re writing, in order to prevent data loss.
The Cloud: companies fail what will they do with your data?

So if your work is irreplaceable, M-Disc is a good possibility especially if you store it off site.

the tan=opp/adj ratio has not changed. the incorrect calc was tan 47=x/50 that's adj/opp that was an error. the correct equation was tan 47=50/x thus x=50/tan 47 not 50*tan47.

Of course the answers are "precise" but equally "of course" they give a minimum height under ideal, perfectly flat conditions.

ARRGGGH! of course the results are the same. I screwed up! x=50/tan(47) or x=50/tan(42) 46.6 and 55.5 ft and 55/tan(47) or 55/tan(42) yields 51.2 and 61 using the 5ft fudge factor.

ARRGGGH! of course the results are the same. I screwed up! x=50/tan(47) or x=50/tan(42) 46.6 and 55.5 ft and 55/tan(47) or 55/tan(42) yields 51.2 and 61 using the 5ft fudge factor.

no. it is the right triangle formed by dropping a perpendicular from the camera point to the ground, touching the ground at a point 50 feet from either side of the 100 foot path. in the diagram "a" is the angle which is half of the 94 degree FOV or the 82 degree FOV of the lens.

Now, note! either 50*tan(47)=53.6 ft or 50*tan(42)=45 ft using either the 94 or 84 degree fov.
Boith assume the unlikely exact positioning at the 50 foot center mark, so if you assume say a 5 ft error in that positioning, use 55 as the target instead of 50. this yields either 55*tan(47) or 55*tan(42) again depending on the actual FOV. These numbers give 58.9 feet and 49.5 feet respectively

I agree with dsmeltz. In fact I would go a little further.

If you get a 1TB external hard drive [with a USB 3.0 connection - this is important for transfer speed to the laptop] and get over the pain of getting to the back of your desktop, you can CLONE the desktop hard drive. That software is usually included with external hard drives from seagate or Western Digital. If not included, there is free cloning software available from Easeus. The cloning can be done overnight - unattended.

You will now have a full backup of the desktop, which is good to have no matter what else. Then connect the external hard drive to a USB 3.0 port on your new laptop and transfer what you want at your leisure. When you're done, you can delete your files from the desktop. You will still have two copies of all your photographs and in fact all of your documents. You might consider then moving that external hard drive to a safe place perhaps off-site.

I have the Pro 100 working with Windows 10 64 bit. It works in all configurations - wifi and wired.
All computers on my network can print to it. You'll have no problem.

But don't use the drivers on the original disk. Go to the website and install the latest windows 10 drives for whatever version of windows 10 you have.