eric gustavo petersen | cinematographer

photographic testing | part one – the lens prep

Photographic testing is just that, testing. Camera test are not just to determine whether or not the equipment is up to standards, but should also be used to understand, in advance, how the equipment and the photographic process will handle real-life situations. If, for example, you want lens flare as part of the show’s aesthetic, then make sure to test the effect of various lighting source on your lenses or perhaps you're doing a bleach by-pass with your interpositive stuck on print stock.

It’s important to insist on testing. Writers get table readings and directors get rehearsals. The director of photography should also be allowed the peace of mind to know if proposed techniques will work in advance. Ultimately, testing trains your eye to see on set what will happen many steps down the production process, which can, in due course, save the production money.

Some of these tests require that you run film through the camera, while others don’t. Of course, you do not have to perform all of the tests. Your experience, time, money and the type of production you’re working on will most likely determine how many of the test can and should be performed. Also, many of these test only require viewing the camera negative, but a few do require that the test be taken though the entire post process, i.e. negative, interpositive, internegative, release print stock. For example, you’re deciding between Super35 and anamorphic, or the effects of filtration or perhaps, when using a special laboratory processes like: bleach by-pass, cross processing, flashing, push/pull, latensification, etc.

LENS PREP TEST:

Registration Test (Steadiness Test)

This test is used to determine the stability of the camera movement and to insure that each frame is photographed absolutely steady. You’ll be making two passes over the same film for about 30 seconds at 50% exposure on each pass. On 35mm film, remove the lens and inch the shutter out of the way and then mark an “X” through the gate on the film. You can align the crosshair on the ground glass to the cross hair on the grid or center of the Siemen’s star. After shooting about 30 seconds, rewind or backwind the film to the starting frame (the “X”) of the first pass. Offset the chart and shoot the second pass. When reviewing, view the camera negative.

First Pass Second Pass

: : click here to see what it might look like : :

This test can also be done with a white cross (made with camera tape) on a black show card.

Flicker Test

Shoot a plain white piece of paper for about one minute. Project the camera original and see if the image flickers or if exposure is even over the whole card. Label the card with the camera’s serial number for two reasons: 1) it lets the lab know the footage is a test and 2) it identifies the film with the camera if working with more than one camera.

Ground Glass Markings (or Projector Line-up Leader)

Used to compare the marking on the camera’s ground glass with the projector mask used for viewing dallies or eventually, in theaters.  Start by locking off the camera six to eight feet and perpendicular from a white show card and trace the marking from the ground glass to a show card.  (A way of doing this is by having one person look through the viewfinder and with a laser pointer mark the spot where a second person can mark the show card.)  Shoot 1000’ for dailies.  It’s a good idea to use a 50mm or 85mm lens for this test.

Lens Sharpness

Fill the frame, from edge to edge, with a high contrast image, e.g. copy from a magazine or resolution chart. Eight feet from the lens should cover most lenses. Use the widest aperture (least depth of field). With zoom lenses, use multiple focal lengths – particularly, focal lengths likely to be used during production. Make sure to light the chart evenly and shoot about 20’ of film for each lens. Identify each lens by placing a label with notes as to the focal length of the lens and serial number. Look for sharpness in the center, corner and edges of the image, contrast, flare, vignetting, and image distortion.

Internal Flare

Set a black square that fills 1/3 of frame against a white background. Light it evenly and shoot 30’ with each lens at production aperture. Look for flaring around the box.

Color Bias

Fill the frame with a white card and shoot about 10’ each lens. Place a label in the frame to identify each lens. Have the editor cut and create a loop of about 5’ each lens. Project and look for the one that pops out.

Breathing

Breathing refers to fluctuation in angular field of view during focusing. Said another way, it’s a zoom lens’ tendency to make an image look bigger or smaller when its focal length is changed. Focus from one end of the lens to the other (close focus to infinity) and see what happens to the edges of the frame. Some lenses breathe more than other while for some it’s so slight, that it’s unperceivable. You’ll have to make the call of what is acceptable. You don’t have to film through the camera for this test.

Don’t forget the other standard camera prep tests: check lens marking, as well as the in-between marks / scratch test / etc. Another interesting test is Flare Characteristics. Film a bright, specular light or the sun to see what kind of lens flare is created.

For additional information about these tests,

consult the ASC Manual (ASC Press) or Camera Assistant (Focal Press).

I would like to thank Richard Crudo, ASC and Oliver Stapleton, BSC for their instruction.

COPYRIGHT 2003.

This material is the sole property of Eric G. Petersen.

This material may not be changed, reproduced or cited without the expressed written consent of Eric G. Petersen.