Focusing Anamorphics

The following tips are designed for theaters who have a sharp focus on their flat (1.85x1) films but NOT on their scope (2.35x1) films.


Materials required:
*A loop of SMPTE 35PA test film as pictured above.  If you have a loop of the older "RP40" test film, that will work fine also.  To properly focus an anamorphic you will need a loop of this.  SMPTE can be contacted at 914/761-1100.
*About 5 minutes of your time.
NOTE:  If your theater cannot focus sharply on flat films, do not bother with this adjustment as there is something else in your theater's equipment out of alignment.  Contact your engineer.  This tip was posted here due to several inquiries about poor focusing on scope films only.

1. Thread the loop of PA35 test film into the projector, making sure the loop does not hang in front of the lens.  Depending on the particular anamorphic you are using, you may have a small thumbscrew, set screw, or a ring collar at the front of the lens.  Loosen the locking mechanism so that you can freely turn the outer focusing ring (labeled with measurements, commonly from 20 feet to 150 feet).  Note the current setting before changing it for reference.

2. Turn the focusing ring all the way down as low as you can go (about 20 feet).  If you are in a short throw theater, such as a screening room, you might be better off turning it to it's infinite setting (typically 150 feet).

3. Turn the projector and lamp on.  Notice the image will be incredibly blurry.  Use the projector's focus control to focus the horizontal lines on screen to be as sharp as possible.  Ignore all vertical lines.  Once you get the projector's focus set in this manner, do NOT touch it again for the rest of this process.

4. CAREFULLY and slowly, turn the focusing ring on the anamorphic lens itself.  Continue to turn it until the vertical lines converge and become as sharp as possible.  Again, ignore all horizontal lines.

5. Now, without bumping the focus setting on the anamorphic, tighten the locking mechanism.

Your lens is now optimized for your projection throw.  Because this method is accomplished by focusing through the lens as opposed to counting the distance from lens to screen (commonly by counting ceiling tiles), your end result will be a sharper image.