Here's the scenario: I see 2-3 movies a week, on opening weekend if possible. There are only 2 "modern" multiplexes in this area, so I've gotten to know them pretty well. I carry around a pretty good database of pros and cons about each location's screens in my head, so I can avoid the dogs and try to stick with the best.

I go to a hypothetical movie, am pleased to find it being shown in a "good" theatre. The show starts, and it immediately looks "soft" to me. I wait for the trailers to finish and the feature to start, and it still looks soft. I try to evaluate whether it's me or some transient problem (aside from just being out of focus). After all, I've been here many times and the projection is usually very sharp. But I conclude it is indeed soft.

I then approach someone on the staff. Might be a manager-type if I don't have to look too hard, or it might be the ticket-taker. I smile and say "I hate to whine, but the focus in Theatre [whatever] looks a little soft. Could you ask someone in the booth to see if they can improve it a little?" I don't make wild claims or accusations to put anyone on the defensive. The staff person smiles, says they will tell the booth. I thank them and return to my seat.

What happens now is universally the same, every time: NOTHING. There is never any visible attempt that I can see that someone is attempting to optimize the focus. The show runs its full length looking soft to me. And nobody else complains (as far as I know).

How do we explain this? Some possibilities:

a) I could be imagining things. I don't think so.
b) The complaint never reaches the booth.
c) The complaint reaches the booth but is ignored.
d) The complaint reaches the booth but falls through the cracks because something else is going on up there.
e) The complaint reaches the booth. The person on duty looks out the glass and proclaims the image "good enough".
f) Longshot, but maybe the person on duty up there is forbidden from doing anything but starting the show?

There may be other reasons. ?

My questions boil down to this:

1) What is your standard procedure for focusing the show and keeping it sharp; and
2) What do you do if someone complains about the focus?

I can't figure out why there wouldn't be a Booth Commandment that says "Manually focus every show whether you think it needs it or not". The next commandment might be "If a customer complains, make a show of focusing it [again], even if the result is no better, so everyone knows it's as good as it's going to get".

Are the optics so stable that they can be focused and will then remain that way for a long time without attention? My theory is this is part of the explanation. If someone does a good focus, with a critical eye, it will probably be sharp for multiple shows, simply by default. Which breeds sloppiness about checking it later. OTOH, if they get it a little wrong, it's likely to stay that way for multiple shows because nobody is really looking at it critically.

Talk amongst yourselves.

(I'm home sick and have a lot of free time on my hands)

once a print is in focus it can stay in focus for a good length of time. friday presentation can be somewhat out of focus due to moving prints around on thursday night. other focus issues arise from opening and closing the lens turret with too much force, causing the lens to be misaligned. dirt and oil on the lens and/or port glass could also cause a problem.

I was strictly a projectionist at an all THX theater equipped with Christie projectors and Schnieder lenses. And we had our problems.

All of the lenses were new. For some reason, the elements in many of the lenses (both flat and scope) loosened up to the point were focus could not be held and most lenses had to be sent in on rotation for repairs. It took a long time to get them back, and our theater chain had to exert some muscle to get prompt service. Can you imagine what a scheduling headache this was for us!

Some of the early turret lock mechanisms on the Christie projectors did not hold the turret still and were a pain! This problem has been corrected with better parts/revised design.

On one occasion, a patron threw a massive spit wad on the port window. I was quite busy and did not have enought time to go downstairs to correct the situation, so I asked one of the floor managers for help. This manager sent in a floor staff person who proceeded to knock off the spit wad with a filthy broom! Needless to say that the the window was badly smeared and the idiot also scratched it! What a pain it was to get clean!

At this theater, the projection equipment and port windows were installed prior to the booth being painted! Needless to say, the windows and equipment have black overspray on them!

This theater is largly used for promos. They even had the major film studios come in to run "unmarried" prints for audience feedback prior to final editing and release. Can you believe that the studio "tech" realigned our projector to the screen for their own purpose. And instead of cutting new plates, they masked the port window, rendering some damage! They did not even right things when they were finished! Luckily we were able to realign the equipment via the marks left in the flooring.

I recently went into a theater to see a first run "scope" picture--a film that was supposed to be a blockbuster--but stunk! Anyhow, the picture was severly "cocked" on the screen--probably the result of an incorrectly installed "scope" lense. I complained to the theater management 3 times--hoping that they could correct it during the previews. Needless to say that they did not know how to correct the situation and were not interested in me assisting them with the adjustment! One of the managers even told me that the picture had been like that for at least 3 years--and their "tech" was aware of the situation!

When focusing a picture between each show I cleaned and inspected both the port windows and lenses. The best way I found to inspect is to look at the surfaces on an angle with a flashlight. This definately highlights dirt and smears! When cleaning lenses, apply only a little solution to the tissue and lightly wipe in a circular spiral motion from the center out. Never apply solution directly to the lense! Kinda sorta the same wiping method used for cleaning reflector mirrors. Also, focusing itself must be done on a steady constant image--such as titles, greenbands or RP40--which can also be used to check lense resolution.

g) poor quality labwork, and the print itself is soft

it is somewhat rare, but it does happen, and you'll see here from time to time, that an entire run of prints, or certain reels of a certain film, can be bad, or that a particualr lab's work is notoriously shoddy.

The unfortunate reality though is tied to you "e)," and that is:

h) someone doesn't give a shit

I'll start the thread by saying that the film "Innocence" is probably the BEST film to watch if you want to judge focus. The combination of tattersol shirts and Harris Tweed jackets make this a film where you KNOW when the film is in or out of focus. (Fujicolor, sorry John)

Focus problems can be caused by bad lenses, bad adjustment of the reflector, dirt on lens or port glass, bad intermittent, dirt in the gate, or a number of other problems.

I always used to focus on the grain for coarse focus, using a pair of binoculars. Once I had the grain in focus, I would tweak the lens to get an overall pleasing focus. I'll have to admit that this was with B&L lenses of the 1970s, and I never was totally pleased with the results.

The primary problems that I have seen in poor focus since that time have been dirt or oil on the rear element of the lens. I can't count the number of times I've gone into a theatre as a DM and been disappointed with the focus, gone into the booth, and found a rear element that needed immediate cleaning. (Although one time, I found a port glass that had been sprayed with oil from a leaking projector, making the left third of the screen out of focus while the rest of the picture was crystal clear.)

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For the most likely reason, I'll pick answer...
g) The complaint never reaches the booth because no one is there.

While the image is usually pretty stable, it still needs to be tweeked even while running.

Sometimes, the heat from the lamp will change the focus as parts expand. If the operator set the focus in the middle of a film, it may be out when the next show starts, because the projector has cooled down during intermission.

I find some lens elements loose because people will grasp a lens and use it to spin the turret, unscrewing the lens. This happens a lot with Simplexes, because there's no knob to grab.

For focusing screens far away, I usually turn the focus knob until it is clearly out. Then, I turn it the other way until it's out again. I keep rocking it back and forth, reducing the distance each time, until it doesn't get any better. So if it's out at say the 12:00 position, and out again at the 6:00 position, then it must be good at the 3:00 position.

I'd like to nominate a single lens Cinemecannica V8 as the best designed focus rack (but not lens holder!) The knob is easy to turn with no play, and the screw thread pitch used moves the lens at a reasonable distance without too much twisting. Simplexes and Centurys have the right thread, but there's always a loose slop "dead spot" backlash where nothing happens... it confuses you while you're focusing. (The Simplex turret focus knobs are a disgrace.) There's no slop in a AAII, but the thread is so fine, (and the knob too big) you have to twist it too far to get the lens to move; sometimes having to remove your hand to turn more - preventing a quick focus.

PS: Hope you feel better, David!

The depth of focus decreases with shorter focal length lenses. Stopping down a lens (e.g., Isco "Studio" lenses) increases depth of focus.

At Kodak, we have equipped our screening rooms with remote controlled focus motors so focus can be precisely set from within the auditorium.

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Evans A Criswell
Huntsville-Decatur Movie Theatre Information Site

Poor gate alignment/tension is the most common cause. Poor lens alignment or severe keystone distortion can also result in uneven focus across the screen.

Focus uniformity should always be checked and adjusted with the SMPTE 35-PA (RP 40) Projector Alignment film:
http://www.smpte.org/smpte_store/test_materials/

Lens turret alignment will cause L/R focus problems if the adjustments are not correct. The lens needs to be perpendicular to the film plane. Typically, the shorter the focal length of the lens, the more critical this alignment is because such lenses usually have less depth of focus. You'll probably notice the problem more with Flat pictures than with Scope, often because of the longer focal lengths.

There's also "perspective control" where the lens is intentionally shifted off axis to attain a required alignment or position on screen. Every lens has a "circle of acceptance" where the image can still be passed by the lens without noticeable problems, even though it is off its optical centerline. However, as you approach the edge of that area, focus may become an issue before the lens actually begins to vignette the image on film. This, too, is a critical part of the lens turret alignment to the film plane.

I have to rock the focus backwards and forwards to determine the "least fuzzy" point. This is not helped by arty director's (anyone seen the opening titles of "101 Rekyjavik"?) and subtitled prints where the subtitles are out of focus relative to the picture.

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