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Topic: flat magnification

Iben Jimenez
Film Handler

Posts: 27
From: Cayey, PR, US
Registered: Mar 2006

posted 07-23-2006 11:12 AM

When using scope, I know that the bigger magnification in the horizontal plane unsqueeze the image, because it is compressed in the film. But for flat format, I have magnification also and the image is not compressed. So why the flat image is not distorted when it is projected?

Thanks

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Patrick de Groot
Expert Film Handler

Posts: 161
From: Sprang-Capelle, Netherlands
Registered: Apr 2001

posted 07-23-2006 12:46 PM

Because with WS it is not an squeezed image, hence you don't need the anamorphic attachment.

Projector Loops
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f/number, focal length, throw, image size ?
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Really read a book or some documentation about film projection before asking this type of question repeatedly.

What is your next question? How does film move through the projector?

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Richard May
Phenomenal Film Handler

Posts: 1057
From: Floral Park, NY USA
Registered: Aug 2004

posted 07-23-2006 01:47 PM

If you dont like the questions, then dont answer it. This site is also here for people to learn!!!

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Darryl Spicer
Film God

Posts: 3250
From: Lexington, KY, USA
Registered: Dec 2000

posted 07-23-2006 01:59 PM

quote: Iben Jimenez
When using scope, I know that the bigger magnification in the horizontal plane unsqueeze the image, because it is compressed in the film. But for flat format, I have magnification also and the image is not compressed. So why the flat image is not distorted when it is projected?

Thanks

The anamorphic attachment on a scope lens handles the unsqueezing of the picture. The magnification has nothing to do with the unsqeezing process only the blowing up of the image to fit your screen in relation to the distance of your projector from the screen. That is why there is no distortion in a flat image only loss of light can be encountered with the magnification issue on flat images. A lot of that is do to poor design of lamp-houses.

There are no stupid questions on this site in my opinion.

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Patrick de Groot
Expert Film Handler

Posts: 161
From: Sprang-Capelle, Netherlands
Registered: Apr 2001

posted 07-23-2006 02:01 PM

You have to do some investigation yourself before asking a question and suspects someone else to give the answers. Especialy with fact questions like these (why x?).

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Darryl Spicer
Film God

Posts: 3250
From: Lexington, KY, USA
Registered: Dec 2000

posted 07-23-2006 02:15 PM

So what is the differance between reading this site and reading a book. We are basically creating a book with all of our posts for people to read. If someone wants to post a question no matter how simple or complex the question may be I see no problem with asking it.

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Richard Fowler
Film God

Posts: 2392
From: Ft. Lauderdale, FL, USA
Registered: Jun 2001

posted 07-23-2006 02:25 PM

Iben, Wide screen non-anamorphic images became popular in the early 1950's by using the aperture plate to crop the existing images. The overall flat film image is much larger, usually 1.37/1 net ratio. Cinematographers make sure that the image they want to show is within that aperture ratio ( 1.85/1 and 1.66 to one are the ratios most used ).
There is some literature, such as Kodak Film Notes, on this web-site. The BKSTS / Moving Image Society has a projection manual and a trade magazine for projectionists. Generally projection books are few and far between that are current. At one time I had over 400 technical books and 1000's of trade magazines in my library, which over the past five years I have sold most of them.
Having been involved in assisting and training techs, one to one and large groups, in many foreign locations ( and Puerto Rico )......every "dumb" question is someone's knowledge building block [Cool]

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Monte L Fullmer
Film God

Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004

posted 07-23-2006 06:53 PM

I'll tell ya, if no-one ever started to ask "dumb" questions, we wouldn't be as smart as we are now - one has to start somewhere to begin the quest for knowledge.

Shoot, been in this field for 37 yrs...and I STILL ask "dumb" questions from time to time...

..Why do you think that I (or, any of us in the same breath) like to spend tons of time here on FT in the first place - to ask "dumb" questions and soak in the knowledge that is available that I (or, some of us) never knew about anything from the git-go since I (or, some of us) was/were never professionally trained in this field in the first place?

Then, what knowledge that is gained, we can then be the teachers for the up and coming that want to learn about this field...and so down the line...to keep this field in existence.

Thus, flat is imagery on the film that looks normal and requires a simple lens, and scope is imagery on the film that is compressed and needs the anamorphic lens to expand the image to normal prospectives on the screen, but making a wide picture in the meantime..

-Monte

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Gilbert Travin
Expert Film Handler

Posts: 101
From: Villeurbanne / France
Registered: Jan 2004

posted 07-24-2006 04:06 AM

Hi !
If I have understood well the question, I think, the answer is simple :
* Standard lenses used for flat formats are spherical : magnification is obtained in all space directions without distorsion ; the ratio of magnification depends of the focal length value ;
* Cinemascope lenses are cylindrical and the 2x squeezing effect is obtnained only in the horizontal direction, they have no effect vertically therefore the anamorphic lenses do not determinate the dimensions of the picture on the screen ; the magnification is obtained with the primary lense placed before the anamorphic device. (anamorphic lenses have not focal length one says they produce angular magnification)
It is easy to verify that. If you use only anamorphic device, it is impossible to have a picture on screen ; if you use only primary (spherical lense), you have a squeezed picture that matches the screen height.

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 07-24-2006 11:07 AM

Some good discussion and history on the American Widescreen Museum:

http://www.widescreenmuseum.com/widescreen/squeeze.htm

quote:
If the word anamorphic seems like Greek to you then don't feel bad. Anamorphic's roots ARE Greek. According to Athens based Director of Photography Argyris Theos the word is derived thusly...

"ANAMORPHICOS" is a composite adjective that derives from the words "ANA" and "MORPHI".
"ANA" is a preposition that is equal to the English "RE".
"MORPHI" is a noun that means "SHAPE".
"ANAMORPHICOS" in Greek, "ANAMORPHIC" in English is by consequence "HE WHO IS BEING RESHAPED".

http://www.widescreenmuseum.com/widescreen/wingcs1.htm

quote:
If Cinerama was the star that guided the film industry into wide screen presentations, CinemaScope was the rudder that steered the course. Studio executives ran for the doors after seeing Cinerama's premiere in New York. Representatives of 20th Century Fox and Warner Bros. literally raced to France to meet with Prof. Henri Chrétien, the inventor of a filming process that he called Anamorphoscope. Fox beat out Warners by just a few hours, so the story goes. Chrétien had developed and patented his process in the late 1920's. Efforts to interest not only his native French but foreign film makers in his wide screen process had been unfruitful for over 25 years. In fact, his patents had expired. So why were two major studios keenly interested in negotiating with Chrétien? The answer is simple, they needed the lenses that Chrétien had built. Those lenses, which he named hypergonar.

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Iben Jimenez
Film Handler

Posts: 27
From: Cayey, PR, US
Registered: Mar 2006

posted 07-24-2006 05:24 PM

Guys, thanks for your kind replies and comments.
To Mr. Patrick de Groot: IF YOU WANT OTHERS TO RESPECT YOU, YOU MUST SHOW RESPECT FOR OTHERS FIRST.

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Bill Enos
Film God

Posts: 2081
From: Richmond, Virginia, USA
Registered: Apr 2000

posted 07-24-2006 06:05 PM

In the for what it's worth dept. on our screen where only the width is changed between flat and scope, the flat image is magnified 63% more than scope as determined by comparing aperture area to screen area.

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Iben Jimenez
Film Handler

Posts: 27
From: Cayey, PR, US
Registered: Mar 2006

posted 07-24-2006 06:11 PM

It would be very interesting to see how the anamorphic lens unsqueezing is produced by the lens, I mean in terms of physics.

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Ron Curran
Jedi Master Film Handler

Posts: 504
From: Springwood NSW Australia
Registered: Feb 2006

posted 07-24-2006 06:48 PM

Look sideways through an ordinary drinking glass and turn it at an angle till your view is distorted. This is a simple way of discovering how the optics work.

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Gilbert Travin
Expert Film Handler

Posts: 101
From: Villeurbanne / France
Registered: Jan 2004

posted 07-25-2006 05:02 AM

Hi Iben !

The anamorphic set-up is composed of several lenses diverging and converging which focal points are confused("telescope" assembly)
There is a link on Wikipedia that shows how lenses function.
"http://en.wikipedia.org/wiki/Lens_%28optics%29"
There is on the right hand of the topic a photo showing the light beam trough a cylindrical lense.
Prof henri Chretien had found the good word for his anamorphic lense : the Hypergonar from hyper [Big Grin]

and gone = angle ; this set-up expands angles with a factor of 2.

[ 07-26-2006, 01:34 AM: Message edited by: Gilbert Travin ]

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