35 mm Adapter without GG at DVinfo.net

Mike Metken · June 12th, 2004, 04:01 PM

Here's an idea that may possibly work. You project the image on a perfectly white surface.Then you would be aiming the camera at the surface from the same side. The angle between the 35 mm lens and the camera lens would be minimal. You would then use special optics to take care of the image distortion and to focus properly at that angle. You could install the special optics at both sides, for the image to project undistorted and in focus and for the camera to see the image undistorted and in focus. I don't know anything about optics but Edmunds or someone could suggest what to do. Probably a simple single lens that would be turned slightly. No ground glass, no moving parts. But maybe too complicated.

Mike

Valeriu Campan · June 12th, 2004, 06:37 PM

<<<-But maybe too complicated.
>>>

Couldn't agree more

Frank Ladner · June 12th, 2004, 10:09 PM

Mike: That is a good idea. Some of us have talked about something similar to what you describe, but I think it would be pretty complicated. However, don't let that keep you from trying it out!

,Frank

Brett Erskine · June 12th, 2004, 11:35 PM

Last time this was talked about I mentioned one of my early designs. It works on the same basic idea of video taping the 35mm image after it is projected on a solid white surface. Basically what your talking about is a front projected image versus a rear projected image which is the idea behind the designs using ground glass instead. So if you want to try doing a front projected design without special corrective optics you can do it with one 2-way mirror and one normal mirror. Thats it. Simple.

Heres how it works. The image from the 35mm lens is projected on a flat white surface but not before passing straight thru a 2-way mirror. The 2-way mirror is tilted forward at a 45 degree angle. This mirror allows the video camera to view the white surface at the EXACT same angle as the 35mm lens.
The second mirror (which is just a regular mirror) is placed directly below the 2-way mirror and at a rear tilted 45 degree angle. With this mirror your able to have the video camera mounted the way you want it to - in the same direction as the 35mm lens. Throw it in a housing and your done.

I know its hard to picture a design from just text so let me know if this doesnt make sense. Its a good design without any grain. It has only one draw back...light loss.

-Brett Erskine
www.CinematographerReels.com

John Cabrera · June 13th, 2004, 12:21 AM

How much more light loss than the light loss we get with the current GG designs? I don't think I've ever really seen a 2-way mirror... unless you count oakly sunglasses... will the mirror coating cause the amount of light loss one would see with mirrored sunglasses?

John

Mike Metken · June 13th, 2004, 02:45 AM

Brett,

I thought about the 2-way mirror too, but then I figured too much light loss. I don't know anything about 2-way mirrors and on what principle they work. Does anyone know?

Mike

Brett Erskine · June 13th, 2004, 02:14 PM

Oh yeah I forgot to mention that my design also flips the image up right in the process BUT you still have to correct for left and right.

You can easily do this with most video cameras. Just look for some type of feature in the menu that flip the image left to right. Usually its called "mirror".

Another thing for thoughs that want to make one and make one right - buy optical grade mirrors.

The who, what, where, why and how much can be all found on the internet. Give yourself a e-dumaction.

-Brett Erskine

June 12th, 2004, 04:01 PM	#1
Mike Metken Join Date: Jun 2004 Location: Carlsbad, CA Posts: 73	35 mm Adapter without GG Here's an idea that may possibly work. You project the image on a perfectly white surface.Then you would be aiming the camera at the surface from the same side. The angle between the 35 mm lens and the camera lens would be minimal. You would then use special optics to take care of the image distortion and to focus properly at that angle. You could install the special optics at both sides, for the image to project undistorted and in focus and for the camera to see the image undistorted and in focus. I don't know anything about optics but Edmunds or someone could suggest what to do. Probably a simple single lens that would be turned slightly. No ground glass, no moving parts. But maybe too complicated. Mike

June 12th, 2004, 06:37 PM	#2
Valeriu Campan Major Player Join Date: Mar 2004 Location: Melbourne, Australia Posts: 223	Re: 35 mm Adapter without GG <<<-But maybe too complicated. >>> Couldn't agree more

June 12th, 2004, 11:35 PM	#4
Brett Erskine Major Player Join Date: Dec 2003 Location: Anaheim, CA Posts: 445	Heres one simple way to do it Last time this was talked about I mentioned one of my early designs. It works on the same basic idea of video taping the 35mm image after it is projected on a solid white surface. Basically what your talking about is a front projected image versus a rear projected image which is the idea behind the designs using ground glass instead. So if you want to try doing a front projected design without special corrective optics you can do it with one 2-way mirror and one normal mirror. Thats it. Simple. Heres how it works. The image from the 35mm lens is projected on a flat white surface but not before passing straight thru a 2-way mirror. The 2-way mirror is tilted forward at a 45 degree angle. This mirror allows the video camera to view the white surface at the EXACT same angle as the 35mm lens. The second mirror (which is just a regular mirror) is placed directly below the 2-way mirror and at a rear tilted 45 degree angle. With this mirror your able to have the video camera mounted the way you want it to - in the same direction as the 35mm lens. Throw it in a housing and your done. I know its hard to picture a design from just text so let me know if this doesnt make sense. Its a good design without any grain. It has only one draw back...light loss. -Brett Erskine www.CinematographerReels.com

June 13th, 2004, 12:21 AM	#5
John Cabrera Regular Crew Join Date: Apr 2004 Location: California Posts: 67	Light loss How much more light loss than the light loss we get with the current GG designs? I don't think I've ever really seen a 2-way mirror... unless you count oakly sunglasses... will the mirror coating cause the amount of light loss one would see with mirrored sunglasses? John

June 12th, 2004, 10:09 PM	#3
Frank Ladner Major Player Join Date: Aug 2003 Location: Poplarville, MS Posts: 453	Mike: That is a good idea. Some of us have talked about something similar to what you describe, but I think it would be pretty complicated. However, don't let that keep you from trying it out! ,Frank

June 13th, 2004, 02:45 AM	#6
Mike Metken Join Date: Jun 2004 Location: Carlsbad, CA Posts: 73	Brett, I thought about the 2-way mirror too, but then I figured too much light loss. I don't know anything about 2-way mirrors and on what principle they work. Does anyone know? Mike

June 13th, 2004, 02:14 PM	#7
Brett Erskine Major Player Join Date: Dec 2003 Location: Anaheim, CA Posts: 445	Oh yeah I forgot to mention that my design also flips the image up right in the process BUT you still have to correct for left and right. You can easily do this with most video cameras. Just look for some type of feature in the menu that flip the image left to right. Usually its called "mirror". Another thing for thoughs that want to make one and make one right - buy optical grade mirrors. The who, what, where, why and how much can be all found on the internet. Give yourself a e-dumaction. -Brett Erskine