There are adapter which allow you touse 35mm opjectives on MiniDV or 16mm
Cameras, but they use an internal diffusing screen and your camera is "just"
filming this screen. But I don't think that they have used this.
If they have used a 16mm lens with the same lens angle (not same focal length)
as the 35mm, then it is wrong, too. They have different distortions.
And at last you have different film backs, if you use cameras of a different
type (exspecially with the 35mm Adapter). It can be that the grid footage is
perhaps a bit smaller/bigger than the 35mm footage, which results in a wrong
un-distort filter.
Same problem could occour if you transfer your negative to digital footage.
If you scan 16mm and 35mm, then you have different crops.
Holger SchÃnberger
technical director
The day has 24 hours, if that does not suffice, I will take the night
On Tue, 9 Jan 2007 at 15:42:25, Adam Seeley wrote:
> Hello all,
>
> Here's a head scratcher for the day, (well mine anyway).
>
> We have a whole bunch of plates that have been shot 35mm Full Aperture on
> various Prime lenses. e.g . 10mm, 24mm, 50mm, 180mm
>
> Lens Distortion Grids have been shot for these plates using exactly the same
> lenses (matching serial numbers), but have been shot onto 16mm.
>
> My instant reaction is that this is wrong and will give us incorrect results
> when we get down to the undistortion, tracking and ultimately the line up of
> CG & live action.
>
> So, I'm just curious to know whether this what's known in the industry as a
> technical faux pas (to put it mildly), or am I missing some basic technical
> savvy.
>
> My basic, possible naive, understanding of film sizes and focal lengths would
> lead me to believe that you would need double the focal length to compensate
> for the 35mm->16mm film size difference, or that to use the same lens you
> would have to shimmy the filmback backwards to observe the same amount of
> distortion across the 16mm film.
>
> I also assume that you would need some sort of lens conversion ring to mount
> a 35mm lens on a 16mm camera which would again slightly change the focal
> length.
>
> Any answers/speculation/inherent knowledge & experience gladly received.
>
> Cheers,
>
> Adam.
>
>
>
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