Film-Tech Forum ARCHIVE: Moving a Projector

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Posted by Sally Ann Burgess (Member # 4746) on 08-20-2009, 08:37 AM:

Right, on one of our Kinoton FP30 projectors, the image is never fully focussed across the entire screen. If we play a trailer that is letterboxed, the black "bar" at the bottom is taller on the left than on the right. The top bar is even all the way across.
I think the projector needs to be physically moved but it won't be easy and I'm a bit concerned about aligning the lamphouse with the projector properly.
It's funny because we have another screen the same size and same projector and the same throw, and the picture is always really clean compared to this other one.
I have been lent some RP40 to help me out but just wanted to know if there was some advice anyone could give me who has experienced the same thing.

Posted by Andy Bajew (Member # 5330) on 08-20-2009, 08:44 AM:

My theater has issues with pillarboxing where you can tell how uncentered the screen actually is. I am not entirely sure exactly what you mean about only the bottom left being higher but the top being fine. If I am not mistaken, wouldn't something like that be the lens that has become slightly rotated? Sort of creating a more diamond-type shape?

However, if it is the moving of the projector you really want to know about, I have done this several times. If you find out you only need to pivot to fix the problem, I typically can use my foot to raise the back of the lamphouse and pivot with my hands. On two occasions I needed to move the lamphouse back and right a few inches--that required me and 3 other guys. You can always get two really strong guys and have them do a pivot thing where they alternate between moving the front and back.

Posted by Sally Ann Burgess (Member # 4746) on 08-20-2009, 09:13 AM:

Thanks Andy. What I meant about the height of the black bar on the LHS is just that the bar is slanted down toward to RHS of the screen. And since we are currently showing Inglourious Basterds, the subtitles are sloping down too!
The lamphouse is on metal legs but the projector was bolted to the floor. I say "was" because I have removed the bolts. I'll mark the carpet to show the projector's/lamphouse's original positions.
Did you move the projector whilst playing a loop of RP40?

Posted by Tim Reed (Member # 137) on 08-20-2009, 09:23 AM:

I'm not familiar with Kinotons, but I've never seen a projector that was actually bolted to the floor. You sure those weren't the levelling feet you removed? They're normally adjusted in pairs, to yaw or tilt the projector by small amounts. You can use them to split the difference in the keystoning on your screen.

You'll probably have to re-file aperture plates as well, after you change the levelling.

Posted by Darryl Spicer (Member # 711) on 08-20-2009, 09:35 AM:

First thing you want to do is project the RP40 using the flat lens. Make sure the bottom horizontal lines of the RP40 are straight and parallel with the bottom of the masking. If your projector sits with an angle you will have a keystone effect at the top lines of the RP40 image. Make all of your projector position adjustments with the flat image. Next use the scope lens and check the horizontal lines on the bottom of the RP40 image. if they are not straight loosen the collar that holds the lens and adjust the scope image by turning the complete lens until the bottom lines are as straight with the bottom of the masking as possible. Once again if you have a angle on the projector you will have a bit of key-stoning at the top of the image. Make sure that you refocus the lens in the barrel before tightening the collar back down. You will also need to cut new plates for flat and scope after doing the adjustments.

If your keystone is to severe you can do what Tim says above and split the difference between top and bottom.

Posted by Mark Gulbrandsen (Member # 72) on 08-20-2009, 10:29 AM:

quote: Tim Reed
I'm not familiar with Kinotons, but I've never seen a projector that was actually bolted to the floor.

You've never worked on the West Coast then... Some locations require it by code for earthquake reasons.

Posted by Scott Norwood (Member # 30) on 08-20-2009, 12:38 PM:

What Darryl said. [thumbsup]

Bolting the machines to the floor is code in Massachusetts, but I've never actually seen it done in practice.

Actually, I have never seen a fully code-compliant booth here. Some don't even follow the basic safety requirements. Of course, the new ones all follow the handicapped accessibility requirements, right down to braille lettering on the doorplates. If I were going to pick and choose which codes to follow, I would personally pick the safety code over the handicapped code, but that's just me....

Posted by Andy Bajew (Member # 5330) on 08-20-2009, 12:56 PM:

quote: Sally Ann Burgess
Did you move the projector whilst playing a loop of RP40?

Both times I moved the projector I left the lamphouse off--I was too worried about the bulb suffering damage or exploding if any of the movements were too rough on the housing. I did all the final adjustments, focus and mirror adjustments after the projector was moved near the spot I needed it to be.

Posted by Monte L Fullmer (Member # 2797) on 08-20-2009, 01:24 PM:

I move the projector with the bulb and machine going-not going to hurt anything. How you gonna find center without any visual guides?

But true, get the RP going without aperture plate and mark the center of the screen to align up with the center vertical line of the RP-40 display that is being projected on the screen.

Then use a prybar at the rear of the base so you can lift the rear end a shad to pivot the rear end around to get front to center..

But, do the RP first to see where you're at before your Herculean employees want to excersize their muscles

-Monte

Posted by Brad Miller (Member # 2) on 08-20-2009, 02:52 PM:

Sally, is this a changeover house? What you describe is the left projector in a 2 projector setup...or your single port window is not centered with the screen. There is little you can do.

Inglorious Basterds is a scope movie, so there is a good chance your anamorphic lens has slipped in it's mount and simply needs to be rotated back level. There is a quick and dirty way to make this look decent (assuming the system was originally setup properly). Run a FLAT letterboxed trailer and re-level the feet on the Kinoton so that the bend is equally off on top and bottom (again when running a FLAT letterboxed trailer through the FLAT lens). That will get your projector leveled as best as it can. Then use a scope pillarboxed trailer and run through the scope lens and physically rotate the lens until the side bars are parallel to the side masking as best as possible (a similar effect will be seen, meaning not truly parallel, so just balance it as best you can). At this point you will see if your aperture was cut poorly and might require a tech to re-cut it, but the lenses will be dangerously accurate without having to use test film.

Posted by Sally Ann Burgess (Member # 4746) on 08-20-2009, 04:05 PM:

Thanks for all the advice, fellas. Very much appreciated.
Brad it's not a changeover house. I have a couple of flat letterboxed trailers I could use, not sure about scope pillarboxed ones but am on tonight and will have a rummage and play with the lens as best I can...
Cheers.

Posted by Sally Ann Burgess (Member # 4746) on 08-21-2009, 11:50 PM:

OK so I needed a bit of help levelling the feet of the projector today, I used some cardboard and now the line at the bottom is straighter than it was. I played a letterboxed trailer loop and adjusted the lenses to get them as focussed as possible, we don't have anything pillarboxed or scope. There is quite a lot of bleed onto the RHS of the masking (nearly a foot) and on the LHS there is a black shadow that comes into the picture by about 6 inches or so.

Posted by Joe Redifer (Member # 3) on 08-22-2009, 02:20 AM:

Just aim the projector a bit more to the left. But before you do, make sure the aperture plate is seated properly.

Posted by Andy Bajew (Member # 5330) on 08-22-2009, 02:25 AM:

The shadow you describe seems like it would be caused from the filing of the aperture plate. I had to file down one of my aperture plates just earlier for the exact same problem. Usually it's caused by the back part of the aperture not being completely straight with the front--filed at an angle.

The bleeding on the masking, I would double check the position of the projector. If it is minor, try just shifting the back of the projector right(pivot on the front right - if you are looking at the back), or just move the entire projector to the left some-that would solve both problems.

Posted by John Hawkinson (Member # 1135) on 08-22-2009, 02:52 AM:

It's not possible to eliminate aperture shadow completely. That's why the picture always projects a little bit onto the masking, to hide the aperture shadow.

Aperture shadow arises because the aperture is not in the focal plane of the film. It is some distance closer to the lens than the film itself (depending on the projector model...).

Yes, it can be reduced by "backfiling" aperture plates, but that's not a a good idea for the inexperienced (plus, it's hard to recover from a mistake). Try to center the image on the screen.

If you have 6" of shadow on the left and 12" off on the right, then it sounds like you'd be perfect if you shift the image 6" to the left. Then you'd have your 6" of shadow projecting on the masking (where it belongs!) on the left, and if you have the same amount of shadow on the right (as you should), that will also all be on the masking.

--jhawk

Posted by Sally Ann Burgess (Member # 4746) on 08-22-2009, 03:12 AM:

Thanks, guys. I have got my Tech hopefully coming in a few weeks so I'll wait and see what he says.

Posted by Monte L Fullmer (Member # 2797) on 08-22-2009, 03:45 AM:

On aperture filing: the trick to help knock off some of that shadow is to have the edges of the opening tapered - with the back side of the aperture plate having the taper to the opening.

Instead of filing straight across, you'd file in an upward direction to put a knife edge on all four edges with the taper on the back side of the aperture.

But, it still doesn't help since on some projectors that the aperture plate is way behind the film plane .. like on some Simplex XL units with the curved gates and those removable aperture plates. This is when masking is deeply needed.

Posted by Joe Redifer (Member # 3) on 08-22-2009, 04:04 AM:

I don't think her problem is the aperture and I don't think she should touch it, BUT...

...I have also noticed that proper bulb focus can play an important role in aperture shadows. It can make HUGE shadows that definitely shouldn't be there and are usually corrected by proper adjustment and focus of the lamp, at least on Simplex XLs.

Posted by Sally Ann Burgess (Member # 4746) on 08-22-2009, 05:00 AM:

Interesting point about the bulb Joe. Monte I'm not going anywhere near the aperture but thanks!!!
Will look at bulb focus tomorrow and report back.

Posted by John Hawkinson (Member # 1135) on 08-22-2009, 05:37 AM:

Just to beat the dead horse, never file an aperture plate unless you have a brand new one to screw up (preferably a few).

Monte...your directions are not very helpful:

quote: Monte L Fullmer

Instead of filing straight across, you'd file in an upward direction to put a knife edge on all four edges with the taper on the back side of the aperture.

How is anyone supposed to know which direction is "upward"? And a taper necessarily goes in two directions. If you have a taper on the back, you will have a taper on the front (unless you taper only half the distance and then change the angle). One side will taper inwards and one side will taper outwards.

(But why are you encouraging Sally to try changing her aperture? No offense to Sally, but we shouldn't be recommending filing apertures to inexperienced people...especially not without a lot of warning and careful direction...there are plenty of older threads. It's too easy to screw up. Not to mention the fact that it sounds like her aperture here is just fine!)

I'm pretty sure you mean tapering such that the back of the plate is larger than the front, i.e. the side of the plate nearest the film tapers outwards.

--jhawk

Posted by Andy Bajew (Member # 5330) on 08-22-2009, 09:49 AM:

With the greatest of respect John, but I completely disagree and feel like I should defend myself and others with your statement about not letting inexperienced people file the aperture plate. Obviously, you won't let a trainee do it, but if they understand how the image is projected and and ratio of aperture size to screen size, then the average projectionist could file an aperture plate. It is just that you need an average projectionist who has a lot of patience, time and a little obsessive compulsion. The head projectionist of three years I replaced couldn't file an aperture plate--long before I replaced him I made two from scratch. Actually, when we first got our projectors we had someone who didn't know a single thing about projection file us all seven aperture plates.

Posted by Darryl Spicer (Member # 711) on 08-22-2009, 11:00 AM:

I agree with John, we shouldn't suggest filing a plate to someone who may have never done it. The big reason is because we are not their to see what he or she is seeing. You could have other issues that may need to be corrected that would not require the filing of the plates. The projector had an original position when it was installed and plates were filed for it. Over time, depending on the type of floor and other things, the picture image can shift. This does not mean you go and file a plate. You have to make corrections in other places like lens turrets or console height adjustments and shifts side to side. If the projector was not set up correctly in the beginning and then you re-set it up correctly later then aperture plates will need to be replaced. Putting a file in the wrong hands can piss off a tech in the future.

Posted by Monte L Fullmer (Member # 2797) on 08-22-2009, 12:42 PM:

I'm not really trying to suggest anything and sorry if it came out that way. Just showing how other techs have trimmed plates.

Posted by Eric Robinson (Member # 2966) on 08-25-2009, 02:03 AM:

Sometimes learning the hard way is the best way. Otherwise you just follow someones rules which might be right or wrong. Who knows.

I made many a mistake when I first took on aperture plates...stupid ones like filing a flat aperture plate when the masking was set to scope. Filing a plate when the lens was out of focus. etc...

Certainly it is not a trivial task and it should not be regarded as such. Indeed techs don't like showing up and finding all of the aperture plates ruined.