35mm adapter - double cameras.

Aaron Shaw · January 15th, 2005, 04:11 PM

Bob, that's precisely a rear anamorphic. I read about that too. It's meant to allow their 16:9 cams to shoot 2.35.

Oscar Spierenburg · January 15th, 2005, 05:00 PM

The first thing that's clear to me after a quick test is that you loose a lot of light with a mirror.
So the next test I'll make tomorrow is to put the two camera's almost parallel (side by side) facing the GG. They must be panned a little to the centre and I’ll loose some pixels when I correct the perspective in post.
If this would be the best method, would there be an optical solution for this distortion?

I'm also curious about rear anamorphics, does anyone know the curve of such a lens?

Barend Onneweer · January 15th, 2005, 05:30 PM

I'm not referring to 'drift', causing the images to run out of sync during a long shot.

I'm talking about the camera's being out of sync due to a different phase of their internal clock. 1/60th of a second timedifference between the two halves of the frame would be a big problem.

I doubt this would be easily fixed in post, but tests will tell...

Bar3nd

Oscar Spierenburg · January 16th, 2005, 06:59 PM

I'm very glad to say that after two heavy tests on synchronisation, the effects we've discussed did not occur. I didn't test it in the 35m adapter, because it's not finished yet, but I made a simple panorama (a bit like the old cinescope with three cameras)
Of course I have a weird lens distortion in the centre, but with panning slow and fast to very fast, no shifting happens.

By the way; the synch between two footages is set up in no time, even without SMPTE signal. I just flashed a light.

Oscar Spierenburg · January 17th, 2005, 05:54 PM

So everything would work with synch and no side effects, is anyone interested in discussing ways to film the projected image with two cams?
The best thing would be to have a resonable overlap to blend the images.
I also thought of filming the whole frame twice and do some sort of pixel shift(if that's the right word), but that's just a stupid Idea, I think.
So, does enyone know some sort of beamsplitting, without much lightloss?

Aaron Shaw · January 17th, 2005, 06:01 PM

You're going to loose half your light if you split the beam. There is no way around this. Whether you loose more than that depends on how you do the splitting exactly. In any case it seems like it would be very hard to pull off well.

Do you have some test footage you can post from the 2cam shoot?

Oscar Spierenburg · January 17th, 2005, 06:21 PM

The footage isn't spectacular, so I won't bother you with it. But the main thing it showed me was no shifting. None when looking frame by frame and none playing normally. Besides that it's crap, because it's without the 35mm adapter and I didn't work on the lens distortion in the centre, so it looks like a raindrop had run vertically. How they did that in cinescope (not cinemascope) I don't know.

If I'd loose half the light, I won’t split the beam.

What if I place the cams almost parallel, like I said, is there a way to correct the perspective with a lens? I mean, you film the image a little from the side.

Oscar Spierenburg · January 21st, 2005, 07:29 PM

I got the setup finished in general. Everything is still uncovered, but the camera's are in place, I have a mirror just like in the drawing I made(if the mirror is exactly 45° the light loss is not too much)

I hope I get some more people interested in this concept.
These are the advantages so far:

-If you have a pretty good (consumer)DV camera which is a few years old, you can probably get the same one for a bargain second hand.
-You have high resolution, 720 x 1040 in my case.
-The system is made not too much more work than a 35mm adapter.
-The camera's share the same remote (and in my case start and stop at exactly the same time)
-If you have the adjustments right in a post software, it can be used every time (just replace the footages), unless you take off the camera's.
-You could have surround sound if you want.
-And of course you have the superb DOF of the augus 35mm system.

I'll do some more testing tomorrow and post some if it is good enough. Of course, no one buy a second camera before I show a full test on synch, color and other corrections.

Bob Hart · January 22nd, 2005, 07:33 AM

Ocar.

It would be a bitch to set up and get focussed correctly, but two perspective correcting SLR lenses might fix the center problem, otherise with separate images from separate identical conventional lenses onto separate Agus's gg's, it might be possible to skew the left lens and right lens and their gg's enough to impart the perspective correction that the specialised lenses achieve so that the edges coincide at the new center.

This might also be contrived to take advantage of the hotspot issue with one lens fading as the other gains.

The downside may be a focal shift from center to outside when pulling focus plus a parralax error.

Oscar Spierenburg · January 23rd, 2005, 05:12 PM

Bob, I don't think it will be necessary. I Made the setup like I fist intended, so without the perspective distortion.
I made a (very) quick test shoot. One of the things I did wrong is setting two different diaphragms.

Here is the test (very much compressed):

http://www.degalerie.nl/1/test4b.wmv

January 15th, 2005, 05:30 PM	#33
Barend Onneweer Regular Crew Join Date: Oct 2002 Location: Netherlands Posts: 111	I'm not referring to 'drift', causing the images to run out of sync during a long shot. I'm talking about the camera's being out of sync due to a different phase of their internal clock. 1/60th of a second timedifference between the two halves of the frame would be a big problem. I doubt this would be easily fixed in post, but tests will tell... Bar3nd __________________ www.raamw3rk.net digital storytelling and vfx

January 15th, 2005, 04:11 PM	#31
Aaron Shaw Major Player Join Date: Jul 2004 Posts: 587	Bob, that's precisely a rear anamorphic. I read about that too. It's meant to allow their 16:9 cams to shoot 2.35.

January 15th, 2005, 05:00 PM	#32
Oscar Spierenburg Major Player Join Date: Jan 2005 Location: (The Netherlands - Belgium) Posts: 735	The first thing that's clear to me after a quick test is that you loose a lot of light with a mirror. So the next test I'll make tomorrow is to put the two camera's almost parallel (side by side) facing the GG. They must be panned a little to the centre and I’ll loose some pixels when I correct the perspective in post. If this would be the best method, would there be an optical solution for this distortion? I'm also curious about rear anamorphics, does anyone know the curve of such a lens?

January 16th, 2005, 06:59 PM	#34
Oscar Spierenburg Major Player Join Date: Jan 2005 Location: (The Netherlands - Belgium) Posts: 735	I'm very glad to say that after two heavy tests on synchronisation, the effects we've discussed did not occur. I didn't test it in the 35m adapter, because it's not finished yet, but I made a simple panorama (a bit like the old cinescope with three cameras) Of course I have a weird lens distortion in the centre, but with panning slow and fast to very fast, no shifting happens. By the way; the synch between two footages is set up in no time, even without SMPTE signal. I just flashed a light.

January 17th, 2005, 05:54 PM	#35
Oscar Spierenburg Major Player Join Date: Jan 2005 Location: (The Netherlands - Belgium) Posts: 735	So everything would work with synch and no side effects, is anyone interested in discussing ways to film the projected image with two cams? The best thing would be to have a resonable overlap to blend the images. I also thought of filming the whole frame twice and do some sort of pixel shift(if that's the right word), but that's just a stupid Idea, I think. So, does enyone know some sort of beamsplitting, without much lightloss?

January 17th, 2005, 06:01 PM	#36
Aaron Shaw Major Player Join Date: Jul 2004 Posts: 587	You're going to loose half your light if you split the beam. There is no way around this. Whether you loose more than that depends on how you do the splitting exactly. In any case it seems like it would be very hard to pull off well. Do you have some test footage you can post from the 2cam shoot?

January 17th, 2005, 06:21 PM	#37
Oscar Spierenburg Major Player Join Date: Jan 2005 Location: (The Netherlands - Belgium) Posts: 735	The footage isn't spectacular, so I won't bother you with it. But the main thing it showed me was no shifting. None when looking frame by frame and none playing normally. Besides that it's crap, because it's without the 35mm adapter and I didn't work on the lens distortion in the centre, so it looks like a raindrop had run vertically. How they did that in cinescope (not cinemascope) I don't know. If I'd loose half the light, I won’t split the beam. What if I place the cams almost parallel, like I said, is there a way to correct the perspective with a lens? I mean, you film the image a little from the side.

January 21st, 2005, 07:29 PM	#38
Oscar Spierenburg Major Player Join Date: Jan 2005 Location: (The Netherlands - Belgium) Posts: 735	I got the setup finished in general. Everything is still uncovered, but the camera's are in place, I have a mirror just like in the drawing I made(if the mirror is exactly 45° the light loss is not too much) I hope I get some more people interested in this concept. These are the advantages so far: -If you have a pretty good (consumer)DV camera which is a few years old, you can probably get the same one for a bargain second hand. -You have high resolution, 720 x 1040 in my case. -The system is made not too much more work than a 35mm adapter. -The camera's share the same remote (and in my case start and stop at exactly the same time) -If you have the adjustments right in a post software, it can be used every time (just replace the footages), unless you take off the camera's. -You could have surround sound if you want. -And of course you have the superb DOF of the augus 35mm system. I'll do some more testing tomorrow and post some if it is good enough. Of course, no one buy a second camera before I show a full test on synch, color and other corrections.

January 22nd, 2005, 07:33 AM	#39
Bob Hart Inner Circle Join Date: Dec 2003 Location: PERTH. W.A. AUSTRALIA. Posts: 4,476	Ocar. It would be a bitch to set up and get focussed correctly, but two perspective correcting SLR lenses might fix the center problem, otherise with separate images from separate identical conventional lenses onto separate Agus's gg's, it might be possible to skew the left lens and right lens and their gg's enough to impart the perspective correction that the specialised lenses achieve so that the edges coincide at the new center. This might also be contrived to take advantage of the hotspot issue with one lens fading as the other gains. The downside may be a focal shift from center to outside when pulling focus plus a parralax error.

January 23rd, 2005, 05:12 PM	#40
Oscar Spierenburg Major Player Join Date: Jan 2005 Location: (The Netherlands - Belgium) Posts: 735	Bob, I don't think it will be necessary. I Made the setup like I fist intended, so without the perspective distortion. I made a (very) quick test shoot. One of the things I did wrong is setting two different diaphragms. Here is the test (very much compressed): http://www.degalerie.nl/1/test4b.wmv