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This topic comprises 2 pages: 1 2
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Topic: A few questions about aspect ratio and 2K vs 4K
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Antti Nayha
Master Film Handler
Posts: 268
From: Helsinki, Finland
Registered: Oct 2008
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posted 01-18-2013 04:33 AM
This is why should install a zoom lens and adjustable masking. The latter is actually a DCI requirement, although sadly it’s becoming more and more popular to ignore it. ![[Frown]](frown.gif)
Traditionally a common image height setup is preferred – that means your screen size is eg. 23.9 x 10 feet to accommodate the widest aspect ratio. Then when you’re projecting 1.85:1 content, you use adjustable side masking to reduce the visible screen area to 18.5 x 10 feet.
Ideally your masking should go as narrow as 1.33:1, or even 1.2:1 to accommodate Movietone silent films. (In the digital world, these are simply pillarboxed 1.85:1 DCP’s.)
Some theatres opt for a common image width solution, where only the top and bottom masking are movable. This might fit some narrow rooms better. However, it’s shunned by traditionalists who tend to feel strongly that Scope image should be larger than Flat, instead of being just shorter.
And some theatres even install four-way adjustable masking, where each of the four sides can be adjusted independently. This can be useful for a specialty venue where a lot of weird old formats are projected.
Edit: Steve beat me to it, and also included some wise words about the anamorphic option.
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Bajsic Bojan
Expert Film Handler
Posts: 190
From: Ljubljana, Si, Eu
Registered: Aug 2008
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posted 01-18-2013 12:35 PM
@Nastia
You first need to understand the very basics.
FLAT film and SCOPE film in digital both use square pixels. The one or the other is not 'stretched' or 'squashed'.
In DCI there are two standardized formats:
1.85 (referred to as Flat sometimes) and 2.39 (referred to as Scope)
The numbers represent aspect ratio, correlation between width and height of a projected image. In 1.85, while the image height is 1 unit, the height of the picture SHOULD BE 1.85 units.
Conversely on a 2.39 picture, while the image height is 1 unit, the width of the projected image should be 2.39 units.
Therefore, it is pretty much clear, that a picture that is projected in "scope" IS WIDER than the picture projected in "flat". Not necessarily physically, just imagine drawing equally high giant SQUARES, where you would get ie 4 side by side in 1.85, you would be getting more than 5 equally high squares side by side in 2.39.
If you project all pictures in the same aspect ratio, you will destroy the desired effect of the film maker(s).
In simpler terms: yes, you CAN project all films at 1.85:1, 2.39:1 or even 1.0:1 if that is what you wish. The problem is, this is completely WRONG.
Projecting a 1.85 film filling a 2.39 screen, you are cropping (as in, deleting, loosing, not showing) 20,6% of the image height. Projecting a 2.39 film filling a 1.85 screen, you are cropping 22,8% of the image width.
Your (everybody's) only options are using a masking system if you don't want to show the unused parts of the screen.
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Nastia Motovilova
Film Handler
Posts: 30
From: Nicosia, Nicosia, Cyprus
Registered: Sep 2012
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posted 01-21-2013 04:15 PM
Hi guys,
Sorry for replying late, I was away for the weekend.
The above clears a lot of confusion. So using adjustable side masking would be the most "right" way of projecting the images as they were intended to be previewed.
quote: Bajsic Bojan
Projecting a 1.85 film filling a 2.39 screen, you are cropping (as in, deleting, loosing, not showing) 20,6% of the image height. Projecting a 2.39 film filling a 1.85 screen, you are cropping 22,8% of the image width.
- How are the above figures derived?
- I also imagined that i.e. projecting projecting a flat film on a scope screen using an anamorphic lens, no picture is cropped - as this would be one of the reasons of using the anamorphic in the first place. For example,
http://www.schneideroptics.com/pdfs/projection/home%20theater%20brochure.pdf
using an anamorphic lens I imagined that the effect would be similar as in p3.
Thanks for all the replies.
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Nastia Motovilova
Film Handler
Posts: 30
From: Nicosia, Nicosia, Cyprus
Registered: Sep 2012
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posted 01-23-2013 09:15 AM
quote: Bajsic Bojan
Projecting a 1.85 film filling a 2.39 screen, you are cropping (as in, deleting, loosing, not showing) 20,6% of the image height. Projecting a 2.39 film filling a 1.85 screen, you are cropping 22,8% of the image width.
Just to clear this in my head, this is when using an anamorphic lens,correct?
Also, as I understand, showing a scope film in a flat screen, are we essentially forced to crop the sides of the scope to fit the width of the flat screen? Using my example above, playing a scope film on a 18.5X10 ft screen, we would lose 2.7ft on each side of the screen - where otherwise the picture would have extended?
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