Film-Tech Forum ARCHIVE: Bad Focus

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Posted by Phil Blake (Member # 2012) on 01-17-2004, 05:50 AM:

Hi all , having real focus issues down here in our cinema 3 , we have an intergrated anamorphic lens in the Vic 5 and it is not possible to obtain sharpe focus in cinemascope , widescreen is fine. The intergrated lens is a Schneider . I noticed 2 allen keys at the lens front one with focus and one with lock written on it. Has anyone had much to do with focusing these lens ?

regards
Phil

Posted by Jack Ondracek (Member # 1466) on 01-17-2004, 06:25 AM:

For anyone with direct experience with this lens, it would be helpful if you would indicate whether this is a new install or if that scope lens ever did work right. If it did, someone's either dropped it or they've made their own "field adjustment"... which also would be helpful to know.

Posted by Leo Enticknap (Member # 534) on 01-17-2004, 09:31 AM:

Sorry if this sounds really obvious, but is it just a bad print?

That having been said I once had a duff anamorph - I think it was an Isco, but can't remember - that made everything look soft as shite. We tried everything: screwing it into a different backing lens, adjusting everything there was to adjust but it just wouldn't give an acceptable picture. It was eventually replaced, which solved the problem.

Posted by John Pytlak (Member # 331) on 01-17-2004, 09:45 AM:

Is the projection throw (distance from the projector to the screen) set correctly? If not, the lens will not focus horizontal and vertical detail at the same point (astigmatism). Here is the procedure:

http://www.film-tech.com/tips/anamorphics.html

Posted by Kenneth Wuepper (Member # 1174) on 01-17-2004, 03:55 PM:

A good test for proper alignment of focus and distance settings is to gently rock the focus knob while watching the screen. The image should "snap" in and out of focus over the entire screen. If you notice that the edges go soft first or the center goes soft first, you need to re-run the suggested alignment.

My first experience with poorly aligned anamorphics was "PATTON" the opening scene with the huge flag and the blurry stars that I saw on the left side. That prompted me to discover for myself the process which is now so well described in the "Tips" section.

Thanks to Film-Tech no others should have to re-invent this technique.

KEN

Posted by Gordon McLeod (Member # 33) on 01-17-2004, 04:08 PM:

When properly set a target of verticle and horizontal lines will have the vertical lines go in and out of focus at the same rate as the horizontal ones

Posted by Jack Ondracek (Member # 1466) on 01-17-2004, 04:47 PM:

Well, with all due respect, it just seems that before he starts loosening lockscrews, the basic questions should be addressed. He hasn't said whether the lens was ever right in the first place, so suggesting he unlock the thing & start twisting the focus might be premature.

Posted by Matt Zeiner (Member # 1914) on 01-17-2004, 06:18 PM:

umm...what real harm can be done anyways? I assume the lens is relatively new - the astigmatism would have to be off quite a large margin in this case. Why not look at the throw indicator and compare that with a rough measurement.

Posted by Chris Byrne (Member # 1563) on 01-17-2004, 08:11 PM:

Hi Phil,

You may have a loose element inside the backing lens. When removed from the turret, give the lens a gentle shake and see if you hear a rattle. If you are working on it for the first time, be very careful that you don't scratch the coating on the element.

Also bear in mind that the throw setting on your anamorphic isn't always in agreeance with the 'actual throw' from projector to screen. If you haven't already got a loop of Target film (RP40), purchase a 10 foot loop from ATLAB. Do some surfing on this site for tips on what to look for in terms of optimum focus.

Posted by Jack Ondracek (Member # 1466) on 01-17-2004, 10:42 PM:

quote:
umm...what real harm can be done anyways?

Only that the suggestions above, while all good and valid when applied to a specific problem, are all over the place at present and are pretty much reacting to assumptions. You assume the lens is relatively new, but you don't know if it was working the day before this thread started. Therefore, the suggested fixes cover just about everything from initial alignment (which shouldn't need frequent repeating), to checking for loose elements (a good idea, but not what you might expect from a relatively new lens). Maybe the thing kissed a concrete floor from 5 or 6 feet, and then none of this matters. We just don't know yet.

This board is full of these situations, where someone asks about sticking a screwdriver into something, only to be bombarded by well-intentioned suggestions, some overly technical and probably not recommended if the problem hasn't been identified first. Eventually, someone even thinks about asking if the poster has the experience, and maybe the authorization to be taking the screwdriver out of the tool box in the first place. So there's the reason for my caution, maybe even curiosity. You wouldn't want to go and twist the volume pots on your amplifiers because you sense a balance problem, only to find that the real culprit is something out of whack in your processor, yet this kind of thing happens all the time and you wind up with a bigger problem than what you started with.

Again, with all due respect, if one of my people called to tell me the scope lens wouldn't focus, my suggestion that they start twisting the adjustments would most likely not be part of that phone call. But then, I would have gone into the call knowing what I had, how long it had been there, and the fact that those lenses had worked just fine up until some time very near when the call came in... all elements of the troubleshooting process that have not been established in this particular situation. Initially, given I'm not blessed with knob-tweakers, finding out that some staff member had decided to realign the lens while I had my back turned would not be high on my list of first expectations.

It's not necessarily wise to suggest changing the whole tire if it only needs a little air.

Posted by Leo Enticknap (Member # 534) on 01-18-2004, 04:54 AM:

quote:
You may have a loose element inside the backing lens. When removed from the turret, give the lens a gentle shake and see if you hear a rattle.

If the backing lens is suspected as the source of the problem and it's one which will unscrew from the anamorph (i.e. the two are not a sealed unit), why not just try projecting something through it on its own, and/or trying the anamorph with a different prime? That should tell you which of the two units is causing the problem.

Posted by Phil Blake (Member # 2012) on 01-18-2004, 06:26 AM:

Thanks for the assistance. ,

To answer some questions , yes the focus has always been out in this cinema from new (on scope only) , we has screened a scope print in 1 and 2 , focus is fine , when screening in 3 focus is shocking. I am amazed the owners have let it go on for so long .
We do have a loop of test film here.

Regards
Phil

Posted by Manny Knowles (Member # 1171) on 01-18-2004, 08:24 AM:

quote:
This board is full of these situations, where someone asks about sticking a screwdriver into something, only to be bombarded by well-intentioned suggestions, some overly technical and probably not recommended if the problem hasn't been identified first. Eventually, someone even thinks about asking if the poster has the experience, and maybe the authorization to be taking the screwdriver out of the tool box in the first place.

Seriously! "Vegas-style" wagering comes to mind sometimes.

Brad's been giving Film-Tech tee shirts to "winners" again, hasn't he? [Big Grin]

Afterthought -- Curiously, the title of this thread applies to BOTH PROBLEMS being discussed! [Wink]

Posted by Phil Blake (Member # 2012) on 01-18-2004, 09:13 PM:

Manny raises some valid points here , should I be attempting to make the lens adjustments ?? , OK I have some 20 years experience and over that time i have successfully carried out all types of adjustments and repairs , however I have never needed to sort out lens issues so I will admit I lack experience with lens adjustments. If I cannot correct the intergrated anamorphic focus by simple adjustments maybe I should call the experts ?

Posted by Gordon McLeod (Member # 33) on 01-18-2004, 10:44 PM:

Bottom line determin what the employer expects you to do and that is it

Posted by Leo Enticknap (Member # 534) on 01-20-2004, 01:28 AM:

As far as I know you cannot cause any damage to the lens by adjusting the throw setting. If the picture is seriously bad already, it seems to me that in this case there is nothing to lose by experimenting.

Posted by Manny Knowles (Member # 1171) on 01-20-2004, 09:20 AM:

Fair enough, but 'little allen screws' were mentioned in the original post and tinkering with those could prove disastrous.

Posted by Randy Stankey (Member # 64) on 01-20-2004, 09:20 AM:

I agree. If done carefully, you have little to lose and a lot to gain. Additionally, I would be inclined to mark (or make note of) the original setting so that, in case you can't fix it, you can at least return the lens to its original setting.

Posted by Kenneth Wuepper (Member # 1174) on 01-20-2004, 04:20 PM:

A word of caution here:

What appears to be Allen key adjustments are actually special sockets which require a factory supplied tool. This was done to insure positive setting and locking of the lens as well as preventing unauthorized tampering with the above settings.

If you have the tool and the authorization then you could perform the adjustment. Lacking either of these assets, you should seek the permission of the owner/operator of the theatre to have their technician make the adjustment and watch like a Hawk. Perhaps you will both learn a great deal from this exercise and the audience will be the benefactor.

KEN

Please refer to Schneider ES Anamorphic data on their Web Page.

Posted by Gordon McLeod (Member # 33) on 01-20-2004, 04:41 PM:

It is a standard metric sized allen wrench that is required
they shipped a wera one with the lens

Posted by Dave Macaulay (Member # 813) on 01-20-2004, 07:34 PM:

The procedure is well described in the "tips" section posting. One screw adjusts the distance focus, the other screw locks the adjustment screw. The only addition to the tips page I want to make is that with "reverse" anamorphics - the internal operation of the lens shrinks the height rather than expanding the width - the procedure is reversed; you focus the vertical lines first and then use the lens adjustment to pull in the horizontals. There's no easy way to tell if your lens is normal or reversed but it will become obvious when the method in the tips page doesn't work right.
You need a test film like RP40 with grid lines. Don't try to do the adjustment without it. In a desperate situation one can get close with a clip of edge to edge credits but that's not a good idea.

Posted by Aldo Baez (Member # 790) on 01-21-2004, 12:32 AM:

I have this same exact problem as well in several theatres, I have tried the procedure on here and it helped a little but not much. I don't think I am doing it wrong but I don't know. Calling a technician out for something like this isn't feasible even though it looks HORRIBLE. It's either have the bottom part of the screen out of focus or the bottom part ok and the top/middle soft, very annoying.

Posted by Gordon McLeod (Member # 33) on 01-21-2004, 10:20 AM:

If that is the case you probably have nothing wrong with the lens but have too much of a keystone proble
If you can focus the top but not the bottom or the bottom not the top those are the odds unless the lensmount of the projector isn't square to the film plane

Posted by Aldo Baez (Member # 790) on 01-22-2004, 08:47 PM:

Would I be able to check if it is square or not? Would I need some advanced tools?

Posted by William Bunch (Member # 1040) on 01-22-2004, 10:06 PM:

Wow! This very same topic brings back a vivid memory of a similar problem I had with a Schneider anamorphic.

Change over theater with two almost new lenses. The lenses were in use for several months. All of a sudden the scope lens on No.2 just does not look right. After much searching and swapping I find out that one of the elements inside the lens has shifted. The symptom was that it was almost impossible to get focus on anything and there was some double imaging.

The lens was not dropped and showed no other sign of tampering. I had to do something and what I remember was loosening some allen screws around a ring facing the film trap. There are two elements in there that must be eliptical. Maybe the first and last. Not sure. I do know that with constant fiddling with that element closest to the trap I was finally able to get back in focus.

The name of the Schneider lens was Cinelux. All lenses even from a single maker may not be created equal. Be advised it took me a whole afternoon to get it back in alignment and was really starting to sweat as showtime got near. I used a wide screen credit roll, white on black to focus on. That was several years ago and we had no further trouble after that.

I was briefed by someone senior to me at the time that I was definitely in uncharted territory. He said the only real way to align one of these is on a test bench with a laser. Guess I was lucky or just so ignorant the angels forgave me. The show had to go on. We are five thousand miles from USA and only have one screen.

You may not want to try this at home.

Bill BuncH
Misawa, Japan

Posted by Chris Byrne (Member # 1563) on 01-23-2004, 04:47 AM:

quote:
to checking for loose elements (a good idea, but not what you might expect from a relatively new lens).

Jack,

You make a valid point, however all things considered (and basic checks such as cleanliness of the lens, etc) that would be one of my first checks along with ensuring the focus is set right and locking screw is tight on the anamorphic.

If an element is in any way loose, the vibration caused by the turret's rotation and sudden jarring when it reaches it limit screw, could work it more so over a period of time.

Obviously you should see this get worse over a period of time, and get to it before it is at a stage where a patron notices [Wink]

.

How often is the problem something simple?

Randy makes a good point to mark equipment so you don't make the problem worse. Sure - know your depth and what you feel comfortable with, but our job often involves dealing with situations that have never happened before. I'm sure a greater percentage of participants on this site have learnt more from 'hands on' than any manual could offer.

Posted by Will Kutler (Member # 770) on 01-23-2004, 09:17 AM:

I made a post elsewhere some time ago. While at El Con, we had a major problem with mmost of our Schneider lenses. These were all new, and for some reason the elements were all loosening up and it was impossible to maintain focus. Needless to say that there were many customer complaints, and we were busy swapping lenses and prints between screens to prevent dark screens. Wjhat a fiasco that was! Anyhow, you could plainly hear the lenses elements rattle around in the housings. The vast majority of the lenses had to be sent back to Schnieder for repairs.

Posted by Phil Blake (Member # 2012) on 01-26-2004, 08:15 PM:

Hi all,

thanks to everyone who offered assistance to me on this problem.
I found a loop of schneider test film and followed John Pytlak's tips page on focusing and I now have refocused the scope lens to a point where is is now quite good. I doubt if it will ever be sharp as the other as cinema 3 is a small cinema with the screen very close to seating the front row is only about 15 feet from the screen.(some bad design work)

Phil

Posted by John Pytlak (Member # 331) on 01-26-2004, 10:16 PM:

Thanks for the credit, but I believe someone else (Brad Miller?) wrote the "tips" for properly focusing an anamorphic lens using the SMPTE 35-PA test film.

Posted by Barry Floyd (Member # 385) on 07-06-2004, 12:44 PM:

Bumping this back up to the top because I'm having a problem with my Scope images.

Lenses: Schnieder 115mm prime + 1/2 Reverse Anamorphic Adaptor.
(Both lenses were purchased NEW in August 2003)
Screen: 25' x 60'
Throw: 325'-0" (Drive-In)

Hanging my head out the back door and looking at the screen, the left and right sides of the Scope image are as crisp as can be, the center of the picture is "fuzzy" and slightly out of focus. It was REALLY noticible on the Spiderman 2 credits, as you could NOT read any of them!!! What's really bad is when customers call from their cell phones to tell you to go focus the "camera".

I've pulled the lens and nothing inside looks to be loose or rattles... Any other suggestions?? Since I am the ONLY one with keys to the lens cabinet, and the only person who handles film at our theatre, I can rule out that the lenses may have been dropped.

My tech (who showed up as a customer on Saturday night) seemed to think that either the projector was not lined up 90 degrees perpendicular to the screen or that something is wrong with the lens. He ran a loop of test film on Saturday night right before the show, and made what adjustments he could. It's still not right.

I didn't have this problem last year....

For what it's worth... the Flat lens and images are razor sharp.

Posted by John Pytlak (Member # 331) on 07-06-2004, 01:44 PM:

Barry:

Sounds like you may have gotten into an issue of excessive radiant energy causing "focus flutter". Perhaps you are "hot spotting" your lamp more to get more light in the center of the screen, or your heat filtration has become less effective with age. Titles against a dark background are often the most critical scene for this issue. Here are some articles that I wrote:

http://www.kodak.com/US/en/motion/newsletters/pytlak/fall97.shtml

http://www.kodak.com/US/en/motion/newsletters/pytlak/winter97.shtml

Gate tension can sometimes help.

Another issue that can make "focus flutter" worse is high humidity or dampness. As the excess moisture in the gelatin film emulsion is driven off by the heat of the lamp, the film changes shape in the gate. Keep your projection room between 50 and 60 percent RH (use air conditioning or a dehumidifier in really humid weather). I know it's tough to do in a drive-in, but try your best to keep the booth humidity in control.

Posted by Ferdinando Innocenti (Member # 2477) on 07-06-2004, 05:17 PM:

If it’s impossible to have a good focus on the center (out of focus at the sides) the problem is not in projector position, but in the lens. It’s important to know how is the focus with the 115 prime. I think you tried to adjust the anamorphic lens; hadn’t it any improvements?

Ciao
Nando

Posted by Gordon McLeod (Member # 33) on 07-06-2004, 05:48 PM:

"My tech (who showed up as a customer on Saturday night) seemed to think that either the projector was not lined up 90 degrees perpendicular to the screen or that something is wrong with the lens. He ran a loop of test film on Saturday night right before the show, and made what adjustments he could. It's still not right.

I didn't have this problem last year...."
Well your tech is wrong as you said the problem wasn't there last year so that rules out postion alignment unless you moved the machine
My bets are on focus flutter due to heat did you put in a new lamp this season
try defocusing it a bit and see if it helps

Posted by Barry Floyd (Member # 385) on 07-07-2004, 10:25 AM:

Our tech "DID" re-focus the lamphouse right at the beginning of the season. We had a "hot-spot" on the lower right side of the screen, and he moved the bulb around in the yoke until the screen was evenly illuminated.

Our lamphouse is a Xenex II, running an Osram 4kw lamp. No "heat-filters" or anything that I can see. I'll take a photo with the digital camera and post it if you guys think it would help.

Posted by John Pytlak (Member # 331) on 07-07-2004, 12:16 PM:

Any chance your lamp alignment and focus got knocked out of position? Your "heat filter" is a "cold coated" dichroic coating on the lamphouse metal reflector. Be sure your lamphouse is well ventilated to keep the metal reflector cool and maintain efficiency in eliminating excess heat.

http://www.kneisley.com/LampH2.htm

quote:
Kneisley Xenex II Lamphouse
Has newest 12.5 inch metal reflector
(computer optimized design), cold coated.
Heat filter not required.

Posted by Gordon McLeod (Member # 33) on 07-07-2004, 01:33 PM:

lamp and lamphouse alignment effect lens focus as they are all part of the same optical system
they are very interelated

Posted by Daryl C. W. O'Shea (Member # 1303) on 07-07-2004, 10:40 PM:

Have you tried running any NEW scope trailers (or anything else... even NEW flat trailers run in scope) since you had the lamp re-focused? It might be possible that you burnt your print.

Posted by Jack Ondracek (Member # 1466) on 07-07-2004, 11:12 PM:

While interrelated, I doubt that lamphouse alignment would make such a difference that his center credits would be unreadable.

Barry... just to toss a hat in the ring... have you cleaned your lenses recently... as in, have you unscrewed your prime lens and used any cleaner on it? I'm wondering if you didn't seal in some of the cleaner before it evaporated. That can put a fog spot in there that will play hell with your focus.

The film probably isn't getting pinched, since you've got a Simplex... and the flat image looks fine.

Posted by System Notices (Member # 2357) on 07-17-2007, 11:12 AM:

It has been 1104 days since the last post.

Posted by Barry Floyd (Member # 385) on 07-17-2007, 11:12 AM:

Three years later, and I'm bumping this one up again. Same theatre (drive-in), new screen (actually 2 years old now), but we're having some scope focus issues again.
Lenses: Schnieder 115mm prime + ISCO 1/2 Reverse Anamorphic Adaptor.
(Both lenses were purchased used in August 2005)
Screen: 25' x 60'
Throw: 350'-0" (Drive-In)

We have a spot in the bottom center of our scope image that stays out of focus. If I adjust the focus knob to bring it in focus, the rest of the pictures goes out of focus. Last night I actually pulled the lens out of the mount and flipped it 180 degrees, and even with the lens upside-down, it was still out of focus. I was hoping that by flipping the lens I could eliminate any loose element scenerios.

Any ideas?

Is it possible that when we tore the machine down several years ago and removed the lensmount, that it wasn't put back in exactly square to the film plane?

I have another projector head I can swap out to see if it makes a difference.

Posted by Darryl Spicer (Member # 711) on 07-17-2007, 12:49 PM:

Have you tried running the RP-40 test film after close when it is completly dark outside and check the focus on the anamorphic. Is the anamorphic maxed out for distance? Had this anamorphic been focusing fine before?

Posted by Louis Bornwasser (Member # 3063) on 07-17-2007, 01:30 PM:

REmove the anamorphic and look at the target film with only the back up lens. This will confirm or deny the anamorphic. Louis

Posted by Barry Floyd (Member # 385) on 07-23-2007, 10:00 AM:

I've found a temporary solution to my Scope focus problem. Like someone suggested to me last week, I took the lens and rotated it 180 degrees in the lens barrel of the projector and the focus problem went away.

That being the case, would that suggest that one of the elements on the lens has shifted?

Posted by Mark Gulbrandsen (Member # 72) on 07-23-2007, 10:46 AM:

If its a Schnelder or ISCO lens its far more likely that the back up lens has a loose element or the whole back up lens is just plain loose from the anamorphic itself. Rotating the scope lens itself may have allowed it to fall back into place... at least for now. If this is the case it will fall out again at some point.

Mark