Film-Tech Forum ARCHIVE: Determining lens and sensor from auditorium.

This is topic Determining lens and sensor from auditorium. in forum Digital Cinema Forum at Film-Tech Forum ARCHIVE.

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Posted by Terry Lynn-Stevens (Member # 7349) on 05-30-2014, 06:12 PM:

Cineplex has just changed the way the present films at Cineplex 24 in Toronto.

In the past, masking was used on all presentations. Starting this week, all presentations for all 24 screens will be projected onto a flat screen regardless if the screen is common height or width. Most trailers and all ads are flat, feature is scope.

Is there a way it can be determined without going into the booth whether a fixed , zoom or scope lens is being used? This should easily help determine the sensor usage.

Case in point. Last week a common height screen would open the masking to show a scope feature, this week the masking is closed and the scope image is letterboxed on the flat screen size.

Posted by Carsten Kurz (Member # 5396) on 05-30-2014, 06:22 PM:

You can be sure they are all using zoom lenses, then with a single flat lens setting.

The number of locations with fixed lenses/anamorphics is probably very small today. You would not be able to order a fixed lens anymore. Why would anyone do that?

Why Cineplex is doing that even if they have common height screens - maybe you could inquire, maybe they would even answer.

- Carsten

Posted by Ron Lacheur (Member # 1126) on 05-30-2014, 08:05 PM:

I'm pretty sure this isn't a Cineplex policy, as I know several booth personnel here in town that work for Cineplex, and they have told me that they have not been informed of any such policy.

It boils down to lazy or incompetence ( most likely both ) as to why the masking isn't set properly.

The fact that someone set up a single screen file for both formats is troubling though, especially in houses with common height screens.

Posted by Brad Miller (Member # 2) on 05-30-2014, 09:12 PM:

They are probably just playing everything in flat so they don't have to jack with macros or cues on the playlists. Scope simply letterboxes itself within flat (with some loss of picture on the sides).

This is what happens when showmanship and professionalism are tossed aside. We end up with masking-less auditoriums and an "all movies in flat" mentality.

Posted by Buck Wilson (Member # 5885) on 05-31-2014, 12:45 AM:

That is disgusting!!

Posted by Justin Hamaker (Member # 2165) on 05-31-2014, 01:06 AM:

One thought that occurs to me is they might have inVision lenses. We initially had these on our projectors and had all kinds of issues with focus drift. If they are having those kinds of problems, I could see where they might decide to play everything in flat to avoid format changes which would lead to focus problems.

Posted by Steve Moore (Member # 4753) on 05-31-2014, 10:48 AM:

Eek, bet that looks naff! Can't beat masking and tabs! Presentation is 9/10ths of the law, or something like that!

Posted by Carsten Kurz (Member # 5396) on 05-31-2014, 10:54 AM:

There was a time when BARCO had a serious flaw in the lens control software, causing lost fokus and zoom setting, that lasted for over a year.
I know quite a few cinemas disabled lens macros during that time completely.

- Carsten

Posted by Steve Moore (Member # 4753) on 05-31-2014, 11:02 AM:

Did barco not issue a software update?

Posted by Carsten Kurz (Member # 5396) on 05-31-2014, 11:23 AM:

Not for a year or so...

Naturally, also Kinotons and Cinemeccanica Barco clones suffered from the same issue.

It was not your ordinary focus drift thing, it was a real issue, but I think limited to B-Series.

I couldn't believe it took Barco so long to fix it. Someone said Barco was in a critical condition at the time financially.

- Carsten

Posted by Antti Nayha (Member # 4980) on 05-31-2014, 11:45 AM:

quote: Carsten Kurz
You would not be able to order a fixed lens anymore. Why would anyone do that?

Sure, you can still get them, for example from Schneider - see brochure.

They are used in many giant screen venues, where you need really short focal lengths. As you can see, the Schneider DiStar+HD goes down to a 0.72:1 ratio on 4K. Apparently they are really good optically, and damned expensive of course.

Posted by Terry Lynn-Stevens (Member # 7349) on 05-31-2014, 11:54 AM:

quote: Antti Nayha

They are used in many giant screen venues, where you need really short focal lengths.

With what you just mentioned, does anyone know if there is a sure fire way of determining whether a cinema is using a fixed vs zoom lense?

Is there some type of clue that would tip you off? for example: changing aspect ratios from flat to letterbox to scope to pillar box.

Posted by Carsten Kurz (Member # 5396) on 05-31-2014, 11:56 AM:

Wow. Even for curved screens, I thought 'digital' lenses for curved screens were an entire myth...

@Terry - as I said, you won't find these fixed lenses in too many ordinary, even large screen, installations. Depending on the programming, and screen/masking, you may be able to see the imager frame in a darkish grey tone around the image.

With a zoom lens, you would sometimes see this frame growing or shrinking with the lens macros, they can easily be seen on unmasked screens once you know what to look for. Depending on the programming of the show, sometimes you see the movie beginning with the lens zooming in and out. That at least is a clear indication of a zoom lens.

On a screen with a fixed lens, this 'black level' is usually visible constantly same size if the emergency lights are not too bright. DLPs typically have bad black levels, so you should be able to find out wether that dark frame stays constant in size between e.g. pre-show and scope movies.

But then it could still be just a zoom lens operated without a format change as you mentioned above.

In that case, the only way to find out is to enter the booth and have a look at the lens.

- Carsten

Posted by Brad Miller (Member # 2) on 05-31-2014, 05:20 PM:

I don't know what DLPs you are referring to, but I've yet to come across a Sony (which is what I'm assuming you are referring to as a comparison) that had better blacks than a DLP. For that matter I've not seen a Sony that had better blacks, colors, sharpness or really anything at all better than a DLP.

Posted by Carsten Kurz (Member # 5396) on 05-31-2014, 06:14 PM:

Brad, I'm not going to discuss Sony things with you.

At 2000:1, the sensor frame is easily visible at spec brightness levels without screen masking. Even more so with the S2k or 4k DLP chipsets operating below 2000:1

- Carsten