These three factors are closely related. Zoom and magnification are directly tied together. Zoom of 1 = 50x; Zoom of 3 = 150x; Zoom of 10 = 500x etc. The magnification is approximate since the field of view of each eyepiece design is different. The field of view itself is an exact calculation of the left to right extent of the image box. In other words, at low power in the example above, the field of view is about 30' for the Moon, and 2' 30" for the space on the sides.
You can zoom in and out in different ways.
To zoom in, simply click with the left mouse button and while holding it down, drag to the lower right, and when you release the left mouse button, the “elastic” box will be your zoomed in area. Your zoom box must also be greater than 5 pixels across. Otherwise the program will do nothing, assuming that you have decided to try and make the zoom box go away. If you don’t like your choice of starting position, the easiest way to cancel it is to drag your mouse back up to your starting point and release it.
Ctrl-o = zoom out (default 1/3.5x)
Ctrl-i = zoom in on center of image (default 3.5x)
Ctrl-m = zoom in using your preferred magnification (default 350x)
These defaults can be changed and saved in the Lunar Calculator configuration file (see below).
You can also choose the “magnifying glass” 
(on the toolbar at the top of the image,) and click on the place that you wish to be in the center of the zoom (default 3.5x). The other glass 
zooms out (default 3.5x), centered on the click point. If you wish to change the default zoom in/out magnifiction, click the Edit menu 
:
then click on "Zoom Factor 3.50x". The following box pops up:
Enter your preferred value. It can be decimal or integer. Do NOT use spaces or any other decimal separator other than a comma (,). If you want to keep this change permanently, you will be asked when you exit the program, click "OK" or "yes" to save the value in the Lunar Calculator configuration file.
This is the custom zoom group:
You can toggle the visibility of this group on and off by clicking 
"Custom Zoom Group"
"Modify Custom Zoom In" and "Modify Custom Zoom Out" lets you specify each custom zoom factor individually:
Note that you must leave one space between each value, and you must have ONLY 3 values. You can modify the various zoom in/out factors to suit your taste. Enter your preferred values. They can be decimal or integer. Do NOT use extra spaces or any other decimal separator other than a comma (,). If you want to keep these changes permanently, you will be asked when you exit the program, click "OK" or "yes" to save the values in the Lunar Calculator configuration file.
By clicking on the magnification,
you can directly enter a value, or choose from a drop down list (configurable):
.Then click the OK or check box to choose the magnification, and move your cursor over to the point you want to center on.
You may have a preferred magnification when you are studying the Moon. You can specify it under the "Zoom/Mag" menu.
You can zoom directly to your preferred magnification by a right-click:
When you modify the fixed magnifications, the following window appears:
You must enter 6 values. They can be decimal, and do not require the "x", because the program takes care of that.
NOTE: the Clementine imagery on this CD-ROM has a maximum resolution of 0.5km/pixel, or 0.3 mi/pixel. You can zoom in more, but there will be no more added detail. Demo users with the Clementine disk have a maximum resolution of 1.0km/pixel or 0.6 mi/pixel. Demo users without the Clementine disk have a maximum resolution of 3.0km/pixel or 1.8 mi/pixel.
There are more than 6 thousand craters in the database. In order not to display all at the same time, there are 5 settings that allow you to choose what the smallest size crater can be seen in a particular zoom range. There’s a balance between detail and being over-crowded - choose the settings you like. Note that you may want more craters in the mare regions, and fewer in the heavily cratered areas. For more detail on adjusting this filter, see Settings.
Ctrl-o = zoom out by a constant factor
Ctrl-i = zoom in on center of image with a constant factor
Ctrl-m = zoom in with your preferred magnification (configurable; factory default 350x)
New with version 2.3 is a navigation window. When you zoom in, a box shows your location.
You can change the color of the box (in settings), resize the window, place it anywhere on your screen and it will return there the next time you start up Lunar Calculator (assuming you save on exit).