or

## Owl Hunt

A cache by .jpeg
Hidden : 1/10/2012
In Texas, United States
Difficulty:
Terrain:

Size:  (not chosen)

#### Watch

How Geocaching Works

Please note Use of geocaching.com services is subject to the terms and conditions in our disclaimer.

### Geocache Description:

This puzzle was constructed by our son, a recent graduate of another university west of here. Enjoy!

 A convex mirror and a concave mirror are placed on the same optic axis, separated by a distance L=0.6m.  The radius of curvature of each mirror has a magnitude of 0.36m.  A light source is located a distance x from the concave mirror (as shown in figure).  What distance x will result in the rays from the source returning to the source after reflecting first from the convex mirror and then from the concave mirror?  Answer: A.BC m We know a specific camera lens has a focal length of 180mm and an aperture diameter of 16.36mm.  If the correct shutter speed of a certain scene with these values is 1/30s, what would the equivalent exposure be at f/2.8? Answer: B.ADE ms A 35mm camera has a standard lens with focal length 50mm and can focus on objects between 45cm and infinity.  Cameras focus by rotating the lens, therefore increasing or decreasing the lens's distance from the film (or sensor).  What is the upper bound of the range of distances between the lens and the film to focus properly over the 45cm to infinity range? Answer: FG mm N 29° CE.BDC W 095° BC.AGD You can validate your puzzle solution with certitude.

### Inventory

There are no Trackables in this cache.

Find...

### 20 Logged Visits

13      4      2      1

**Warning! Spoilers may be included in the descriptions or links.