Home Store Project Ideas Project Guide Ask An Expert Blog Careers Teachers Parents Students

Camera Lens Testing

Difficulty
Time Required Short (2-5 days)
Prerequisites Must have a camera
Material Availability Readily available
Cost Very Low (under $20)
Safety No issues

Abstract

This is a cool way to learn more about your camera, and how to take better pictures.

Objective

The objective of this project is to measure the quality of a photographic lens.

Credits

Ken Hess

Cite This Page

MLA Style

Science Buddies Staff. "Camera Lens Testing" Science Buddies. Science Buddies, 2 Oct. 2014. Web. 1 Nov. 2014 <http://www.sciencebuddies.org/science-fair-projects/project_ideas/Photo_p001.shtml>

APA Style

Science Buddies Staff. (2014, October 2). Camera Lens Testing. Retrieved November 1, 2014 from http://www.sciencebuddies.org/science-fair-projects/project_ideas/Photo_p001.shtml

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.


Last edit date: 2014-10-02

Introduction

Lens testing can be as simple or as complicated as you desire, resulting in science projects that suit the needs of a wide variety of students. It's a fun way to learn more about your camera and learn how to take better pictures.

Terms and Concepts

To do an experiment in this area, you should do research that enables you to understand the following terms and concepts:
  • The parts of a lens (lens elements, diaphragm, lens coating, focusing mechanism)
  • Aperture
  • Focal length
  • f/stop
  • Barrel distortion, pincushion distortion
  • Chromatic aberration or color fringing
  • Coma
  • Light falloff, vignetting
  • Flare and ghosts
  • Sharpness

Advanced students should also study and learn about:

  • Field curvature
  • Diffraction
  • Modulation Transfer Function (MTF)
  • Subjective Quality Factor (SQF)

Bibliography

To learn about lenses, basic optics, and photography, try these sources: The Brick Wall Test (and other simple tests) The Star Test The US Air Force Test Modulation Transfer Function (MTF)

Materials and Equipment

  • A camera. It is easier to thoroughly test a lens on a camera with a manual exposure control option than on a camera that is strictly automatic. However, you can do meaningful tests even on an automatic camera (a "point and shoot").
  • A tripod is highly desirable for this project, but you can also place your camera on almost any steady object.
  • Some of the advanced tests require a test target. In many cases you can download these targets and print them out. And, if you use a film camera with a target, you'll need a magnifier or a low-power microscope.

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.

Experimental Procedure

Some lens tests are amazingly simple, yet give a good indication of lens quality. Others are very mathematical and more precise. The table below is a brief summary of the tests you might perform. Use your background research to learn about each one, then choose the test that's appropriate for your camera and your science background. The sources listed above are a good place to start, and they will give you detailed instructions about how to perform the tests.

Type of Test Level of Difficulty Type of Camera What You Can Observe
Brick Wall Test Easy Any - Barrel & pincushion distortion
- Light falloff
- Sharpness
Star Test Medium Must have the ability to take "timed" exposures of many seconds duration.

Note that the image sensor in some digital cameras has poor image quality for long exposures, even if the lens itself is good.
- Coma (star trails become fat in the corners even for dim stars)
- Color fringing (bright stars are not a uniform color)
USAF Test Medium Any - Resolution
- Sharpness
MTF Calculation Difficult

This procedure is for a student who is very comfortable with mathematical equations and complicated graphs.
Any - Resolution
- Sharpness

Lens quality varies with the aperture, and for zoom lenses it also varies with the focal length. So, for different trials in your experiment you will want to change these settings. See the table below.

Type of Camera or Lens What to Test in Each Trial of Your Experiment Your Hypothesis
Automatic Exposure Control Only, No Zoom Lens With a basic camera like this you're only doing a single test and you don't really have anything to compare it to. (That's bad for a science project!) So, try comparing two or more different cameras to each other.
Some automatic cameras have an "exposure compensation function". This might allow you to test the lens at up to two f-stops higher or lower than normal. Unfortunately, the photo will also be over or under-exposed, perhaps making your test difficult to interpret.
After finding more than one camera to test, your hypothesis could be about which camera you think will be best.
Automatic Exposure Control Only and Zoom Lens For a camera like this you may only be able to test one aperture, but you can compare results at different amounts of zoom.
If the lens does not read out its focal length, do your tests at the narrowest zoom and the widest zoom, then the focal lengths should be fairly close to the "spec" on the lens. For example, if the lens is marked 24-75mm, then the focal length is 24 mm at the widest view and 75 mm at the narrowest view.
After doing your background research, you should be able to make a hypothesis about which focal length will be best.
Camera with Manual Exposure Control Test your lens at every f-stop. You can maintain the proper exposure by adjusting the shutter speed.
If you have a zoom lens, test every f-stop at each focal length marked clearly on the lens. If there are no focal length markings, do your tests at the narrowest zoom and the widest zoom, then the focal lengths should be fairly close to the "spec" on the lens. For example, if the lens is marked 24-75mm, then the focal length is 24 mm at the widest view and 75 mm at the narrowest view.
After doing your background research, you should be able to make a hypothesis about which aperture will be best.
Tips for doing your experiment:
  • One of the most important things when doing a lens test is to make sure that your camera is absolutely steady during the exposure. Use a tripod or rest the camera on a steady object.
  • If your camera has the capability, use a cable release or the self-timer to trigger the shutter. Like a tripod, this will help to keep the camera steady.
  • If the test you choose uses test targets, or if you do the brick wall test, make sure that the entire area in the picture has uniform lighting. You don't want part of the scene to be in the shade and part in the sun.
  • Lens quality tends to be higher in the center of the image than at the corners, so be sure to examine both.
  • Make sure that you carefully focus your lens if you have a manual focus camera.

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.


Variations

There are many possible variations with a lens test experiment. Here are just a few:
  • Vibration or camera movement while the shutter is open is one of the biggest causes of poor photos. Compare the quality of photographs from a lens test on a tripod versus a lens test when you hold the camera by hand. You'll want to take a number of photos by hand for each test. How much difference is there between handheld photos and tripod photos? How much difference is there among the handheld photos—are some better than others? You could also compare the ability of different people to take "steady" photos, or compare different techniques of holding the camera. Shutter speed will be an important variable when testing handheld photos. Can you measure the impact of shutter speed on photo quality?
  • If you have a camera that uses interchangeable lenses, test a variety of different lens to compare their performance.
  • You can compare the results from different types of lens test. For example, how does MTF compare to a simpler test such as a star test. To do this experiment properly, you should compare the different lens tests for several lens or cameras.

Share your story with Science Buddies!

I did this project I Did This Project! Please log in and let us know how things went.

Ask an Expert

The Ask an Expert Forum is intended to be a place where students can go to find answers to science questions that they have been unable to find using other resources. If you have specific questions about your science fair project or science fair, our team of volunteer scientists can help. Our Experts won't do the work for you, but they will make suggestions, offer guidance, and help you troubleshoot.

Ask an Expert

Related Links

If you like this project, you might enjoy exploring these related careers:

Female physicist working

Physicist

Physicists have a big goal in mind—to understand the nature of the entire universe and everything in it! To reach that goal, they observe and measure natural events seen on Earth and in the universe, and then develop theories, using mathematics, to explain why those phenomena occur. Physicists take on the challenge of explaining events that happen on the grandest scale imaginable to those that happen at the level of the smallest atomic particles. Their theories are then applied to human-scale projects to bring people new technologies, like computers, lasers, and fusion energy. Read more
physics teacher helping student model a nanostructure

Physics Teacher

Our universe is full of matter and energy, and how that matter and energy moves and interacts in space and time is the subject of physics. Physics teachers spend their days showing and explaining the marvels of physics, which underlies all the other science subjects, including biology, chemistry, Earth and space science. Their work serves to develop the next generation of scientists and engineers, including all healthcare professionals. They also help all students better understand their physical world and how it works in their everyday lives, as well as how to become better citizens by understanding the process of scientific research. Read more

Looking for more science fun?

Try one of our science activities for quick, anytime science explorations. The perfect thing to liven up a rainy day, school vacation, or moment of boredom.

Find an Activity