13 Questions to Test Your Knowledge of Camera Lenses

We couldn’t stump you with 13 general photography questions last week, so let’s see how you do on a lens quiz. Answers at the end—peeking is for haters only.

1. A catadioptric lens
A.  uses a design similar to the design of a cat’s eye.
B.  uses refractive glass and reflective mirrors to form images.
C.  is used primarily on night vision devices, like goggles.
D.  is used by eyeglass wearers to correct for nearsightedness.

ATN ThOR 320-4.5X Thermal Sight night vision device.

2. If a lens is designated APO it is
A.  panchromatic.
B.  a U.S. military grade All Purpose Optic.
C.  used by the Army Post Office.
D.  Apochromatic; i.e., it focuses red, blue and green light on the same point.

3. A 50mm lens on a DSLR with an APS-C size sensor has the equivalent focal length of
A.  75mm if attached to a Nikon.
B.  80mm if attached to a Canon.
C.  both of the above.
D.  neither of the above.

4. Mirror lenses produce bokeh that is distinctively
A.  rainbow-colored.
B.  circular, like donuts.
C.  boxy, like tiny rectangles.
D.  absent.

5. Diffraction causes lenses to
A.  lose sharpness at smaller apertures.
B.  be sharpest at their smallest aperture.
C.  have greater depth-of-field.
D.  overcome chromatic aberrations.

6. The T in T-Mount Lenses stands for
A.  Telstar
B.  Telephoto
C.  Tamron
D.  Nothing in particular.

7. If a lens vignettes, it
A.  is ideally suited for infrared photography.
B.  focuses past infinity.
C.  zooms past infinity.
D.  produces images with darkened corners.

8. The ideal, classic focal length for portrait photography with a 35mm camera is
A.  35mm
B.  135mm
C.  85mm to 105mm
D.  50mm

9. A tele-converter is used to
A.  attach a lens to a telescope.
B.  record digital image data.
C.  increase a lens’s focal length.
D.  attach a 35mm film camera lens to a mirrorless SLR.

Film. ©2016 Steven I. Rosenbaum, S.I.R. Marketing Communications, Inc.

10. The red IR mark on some film camera lenses indicates
A.  infrared adjustment.
B.  that it contains infrared glass elements.
C.  county of origin.
D.  manufacturer’s proof mark.

11. A prime lens is
A.  a lens with a fixed (single) focal length.
B.  manufactured by a camera manufacturer.
C.  a zoom lens.
D.  a wideangle-to-telephoto all-in-on zoom lens.

12. A lens element that is described as aspheric is
A.  concave.
B.  plastic composite.
C.  convex.
D.  polished so that it is not spherical in shape.

13. To most photographers, the term bokeh means
A.  it’s time to buy a new lens.
B.  out-of-focus areas of a photograph.
C.  beautiful focus.
D.  made in Germany.

Answers: 1.B, 2.D, 3.C, 4.B, 5.A, 6.C, 7.D, 8.C, 9.C, 10.A, 11.A, 12.D, 13.B.

(If you liked this quiz, check out this one where we ask "13 Fun Questions to Test Your Knowledge of Photography.")

—Jon Sienkiewicz