Displaying negative zoom values textually

Question

Typically, most applications let you zoom in to a document. This is often expressed as a percentage (100%, 200%, 800%, etc...), or as a multiplier (x1, x2, x8). Sometimes they let you zoom in or out. In those situations, you might display a zoom out as 50%, 25%, and so on (MSPaint for example, uses the percentage for display, out to 12.5%).

But my "document" starts zoomed in at 100%, and you can't zoom in any further, only zoom out from there. So the document is always 100% or less, zoomed in.

Some ways of describing these values are:

100%  50%   25%   12.5%   6.25%
1/1   1/2   1/4   1/8     1/16
1.0   0.5   0.25  0.125   0.0625

I feel that these are unintuitive, and would like a "friendlier" way to display zoom values to users. I already have a slider bar, and buttons with a text display next to it:

Part of my issue is that I 'feel' (there goes that word again) that the slider should start at the far left as the default, and increase to the right. But 'increasing' in this context means zooming out, when other applications zoom in when the slider goes to the right.

I'd really like a way to display the textual information in a more user-friendly way (by that, I mean without decimal or fractional values), and in a way where a positive number implies (or is at least 'acceptable for') zooming out instead of in.

One way of doing it is just to have a zoom 'level', instead of an actual measurement. The zoom goes 1,2,3,4,5,6 or whatever, even though the zoom amount might be some odd value like 0.33%.

What are some other options of expressing zoomed-out values textually?

For context, the application is a videogame 2D tile-based map editor, and you're zooming out the map to get a greater look at the entire map or to edit on a larger scale. You never zoom in more than 1:1 (where one game pixel equals one screen pixel).

Answer 1

It may be worth reconsidering displaying any zoom text at all. This is how twitter deals with zooming:

The question I would ask is whether or not displaying text is redundant/necessary. Does the user need to know the zoom percentage? Is this game going to be available for mobile devices as well? If so adding that extra text field is going to reduce the total slider width which will mean you'll have a lower zoom sensitivity.

If it is a requirement to show the percentage/ratio text I would stick to percentage as it is a clear metric most everyone understands.

Answer 2

Google Maps used to have a slider like...

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..but now just uses a plus and minus button...

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...in part because most zooming is done by scrollwheel on a computer or pinching on touch devices.

I agree with Circuitry that the zoom numbers (either % or multiplier) aren't really needed ... unless there's chance that a user cannot guess what the relative zoom level is a glance - such as looking at a fractal.