getting correct framing on groundglass of letus.

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Derrick_SA

Veteran
Has anyone used this method to know if they have the equivelent of a 35mm camera with there adapter? I saw it on the Letus forum, wondering if someone could confirm if it is accurate? it was done by a guy named robbert-jan

the file:

http://www.adeszo.nl/letus/LEX-GG-framingcard.png

The idea is to use an image to get the right framing with a 35mm lens as rerference.

the instructions (i quote):

First you adjust the focus of your camcorder on your groundglass
- Now zoom out with your camcorder lens until you can see the outer edges of the groundglass.
-Then frame the card with the outer markers touching the edges of the groundglass, either by moving it to or from the camera (fixed focal length lenses) or by using the zoom from the still lens. From this point on, do not change the distance from the card and/or the zoom from the still lens.
- Now you can use the zoom from your camcorder to frame the super 35 imageplane or the vistavision imageplane

This holds true for any focal length


thanks,
Derrick
 
The problem is that every camera is slightly different. Some camera will have a higher X-Y offset, forcing you to zoom in more, some lenses can vignetting more than others, requiring individual correction. The biggest issue that that most camera's LCD overscan, so you can never be sure if you're clearing the GG and vignetting or not.

The method I use is to hook up the camera by firewire to a computer, then turn on the NLE and go into live capture mode so that the image is framed within the NLE's preview window. This will be the full frame without overscan and you can adjust the zoom level here.

Then to get Academy framing stick a piece of 8.5'' x 11'' paper on the wall and stand 2 ft away. The edges of the paper should just fill the frame.
 
Huy Vu said:
Then to get Academy framing stick a piece of 8.5'' x 11'' paper on the wall and stand 2 ft away. The edges of the paper should just fill the frame.
Click to expand...
Crucial piece of missing info: you have to be using a 50mm lens for the 2' distance to hold true.
 
rats, we use A4 which is slightly different to 8.5 x 11".

how did you get to the Lettersize at 2ft with 50mm is the right size? maybe I can modify the formula for A4?

thanks
- Derrick
 
It's not absolutely the right size, it's ballpark, but it's close to the ballpark. Look at a field-of-view calculator, a 50mm lens on 35mm academy aperture movie film, at a distance of two feet, has a field of view of about 10.5 inches wide. Hence we use the 11" piece of paper (landscape mode) and just barely clip off the left and right sides, and then you're in the ballpark.
 
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