|
Author
|
Topic: Using Anamorphic lens with DVD projection.
|
|
|
|
|
|
|
|
|
Paul Adsett
Film God
Posts: 5003
From: USA
Registered: Jun 2003
|
posted July 27, 2008 01:22 PM
Graham, the way it works is this. Cinemascope pictures (2.35:1) are of course letterboxed on the 16:9 DVD, so you have black bars above and below the picture when you project, and the picture height is only using about 75% of the projectors LCD or DLP panel height. In other words, about 25% of the projectors imaging panel is unused when projecting CinemaScope. OK, so now we electronically stretch that letterboxed DVD image in a vertical direction (using the ASPECT RATIO menu feature available on most VP's or DVD players) so that the 2.35 scope picture now occupies the full height of the 16:9 projector panel ( and therefore the full height of the screen). We now have a stretched image where everyone is tall and skinny, so it looks just like an anamorphically squeezed image. Now put a 1.3x anamorphic lens in front of the VP, and the image is expanded out to full width 2.35 CinemaScope, with the picture height being exactly the same as your 4:3 or 16:9. This is called a Constant Image Height (CIH) projection system, and is of course exactly what we all have been doing with film for the past decades.
Advocates of this system, claim that using an A-lens in this way results in a brighter, more detailed, picture than that obtained by simply zooming out, because you end up using 25% more of the video projectors picture panel. I'm not sure I buy that argument totally, since an Anamorphic lens is bound to introduce some loss of light and image contrast.
--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj
| IP: Logged
|
|
|
|
|
|
|
|
|
|
Rob Young.
Phenomenal Film Handler
Posts: 1633
From: Cheshire, U.K.
Registered: Dec 2003
|
posted July 28, 2008 08:02 AM
Paul, don't you need a projector which is specifically designed to take the 2.35:1 image (with black bars top and bottom) and stretch it to fill the whole 16:9 panel, as this is quite an unusual manipulation of the image.
My new Optoma is supposed to do this, but I haven't quite figured out how yet - you see several new projectors advertising this feature.
Then when you add the anamorphic lens the image is, as you point out the same height as your normal 4:3 or 16:9 image, but wider still.
I can see the advantage to this over zooming out; firstly, when you zoom out on most video projectors, doesn't the image move upwards, so it isn't central to the screen anymore.
Or, more troublesome, if it is ceiling mounted, the image would move downwards off the screen.
The anamorophic lens kits (I think most decent projector manufacturers now advertise their own kits) are designed to fit to the front of the projector and have motorised rails which slide the lens infront of the lens for 2.35:1 movies. So the image gets wider than 16:9, but stays screen central.
Also, depending upon the lens on the projector it may not be possible to zoom out for wider images. My Optoma is set at maximum image size and gives a 6ft wide picture. If I had more throw it wouldn't be a problem, but if I wanted a wider picture for 2.35:1 movies, I'd have to use an anamorphic lens with my current set-up.
One last thought is that with HD material, these lenses must (hopefully) be one heck of a piece(s) of quality glass - hence the prices!!!
PS. Just out of interest and slightly off topic, but I used a 16:9 anamorphic lens infront of my old 4:3 chip DLP projector for years with great results. Since the whole panel was in use for 16:9 movies, you got a wider image but with all the horizonatal resolution of the chip. Sure, vertical resolution was stretched a bit, but still a much better picture than zooming out a masked 16:9 image.
| IP: Logged
|
|
|
|
|
|
Paul Adsett
Film God
Posts: 5003
From: USA
Registered: Jun 2003
|
posted July 28, 2008 02:05 PM
Rob, all the Panasonic projectors have a menu button for vertical position. Press this button and you can electronically step the picture up or down on the screen in a few seconds. You do not need to use the manual joystick lens shift feature on the projector lens, that is only used for the initial setting up of the projector and getting it aligned to the screen. When I zoom out for CinemaScope, the picture moves down on the screen. I then press the position menu button to move the picture back up to center. There is a lot of range in the electronic positioning, you can move the image up and down considerably. Its a real fast operation. Also, with my set up, there is no focus change zooming from the 16:9 to the 2.35.
--------------------
The best of all worlds- 8mm, super 8mm, 9.5mm, and HD Digital Projection,
Elmo GS1200 f1.0 2-blade
Eumig S938 Stereo f1.0 Ektar
Panasonic PT-AE4000U digital pj
| IP: Logged
|
|
|
|
|
|
|
UBBFriend: Email this page to someone!
![[Confused]](confused.gif)
all I do is to zoom out and adjust the top and side masking to suit, as far as the image is concerned using the projector and the DVD player set for 16:9 looks fine to me on both the Panasonic and my old Sanyo Z1 projector.![[Roll Eyes]](rolleyes.gif)
just to see what happens you never know ![[Wink]](wink.gif)
Printer-friendly view of this topic
