An LCD shutter is in theory a neat way to deal with the issue.  To my knowledge, they are limited in "dynamic range", they cannot get perfectly clear nor perfectly black.  The latter is not a real problem for our purposes, but the former is.

Are you thinking that a twin camera rig would use a common LCD shutter, or separate?  If a common shutter, the LCD would have to be sizeable.  If separate, you introduce the possibility of mis-synch.  I'm all for this idea (again, in theory), but I don't know if there is an existing product out there that would fit the bill...nor how expensive it would be.

The gravity or guillotine-style shutters are not the way to go.  Anything that involves linear translation is going to suffer from vibration issues.  And for accurate shutter speeds you really need a solution that has a first and second curtain.  Trying to achieve this by varying the speed of the movement of a single shutter/curtain is going to be a miserable task.  It probably will not work.  Approaches that involve varying the slit size are worse still.

I've given this matter a good deal of thought, I'm going to say that as far as mechanical solutions are concerned, the roller blind shutter design will be the only successful approach.  The servo actuators can be "tuned" to allow some overrun of the shutter's movement, thus allowing for a gentler deceleration and thereby minimizing vibration.

And one wouldn't have to mount the mechanism to a tripod.  Just mount it to a bracket that is attached to the base of the camera.  As long as it is not touching the lens itself, it will probably perform fairly well.

I modified the subject so it reflected shutters, as once again, we are all seeking the same holy grails, but now with sync.

Large focal plane shutters are just too mechanical from my experience, and based on John R post as well... they will create shake.  We don't want perfect sync with added blurred images.

If you want the taking rig to be hand-holdable, that is one solution.  If you only use a tripod, you can isolate a mechanical shutter on another tripod with a bellows or cover between them.  talk about cumbersome, feels like the 1800's.    You can do like they did in the old days, use a slit shutter, just pull from top to bottom... smaller slits equal faster shutter speeds.

About 10 yrs ago, when I worked diligently on this, I felt the only sensible solution was a single LED shutter...they were expensive back then.  But they had issues as well...fastest shutter speed back then was only 1/60th, maybe they are faster today... it would make a universal fix for all cameras, as they are lightweight.  Anyone following that field lately?

On Sat, Aug 22, 2020 at 7:46 AM timo@... <timo@...> wrote:

There must be some other way to control the shutter speed of a gravity shutter. All objects fall with the same acceleration regardless of weight. You could adjust the height from which it falls, since dropping it from higher up will get you a faster shutter speed.  I am trying to think of wether the exposure would be different fpr the top and bottom of the frame.

Timo

Sent from BlueMail

On Aug 22, 2020, at 1:27 AM, John Rupkalvis <stereoscope3d@...> wrote:

The Sinar Norma shutter for 4x5 and 8x10 view cameras would be good to look at.  If you prefer focal plane shutters, some of the earlier sheet film cameras, like the 4x5 Speed Graphic and Graphlex cameras were fitted with these.  The problem with those was that you had to reset the shutter speed after every exposure.  Also, they were rather noisy, with a rather loud "Galump" sound every time they were fired.  Some people actually made their own, including the rather interesting double-curtain "gravity shutter" design.  The edge of the curtain was fitted with a lead weight, so triggering the shutter just allowed it to drop, the shutter speed being determined by the size and weight.  Most manufactured versions were spring-loaded.  

John A. Rupkalvis

stereoscope3d@...

On Fri, Aug 21, 2020 at 2:24 PM DaveJes1979 via groups.io <davejes1979=yahoo.com@groups.io> wrote:

I realize we have discussed this before, but for newcomers it should be noted that  "perfect synch" is achievable by the use of a common external shutter.  While there are stand-alone shutter devices on the market, I doubt that any of them would be large enough to cover the lenses of two mirrorless cameras (although I might be wrong on that).

So that means one would likely be looking at a DIY project.  While I am a man of many mechanical talents, my expertise ends where the electronic hardware and software begin.  So I was never able to get the concept off of the drawing board.

On the mechanical side, the important trick is getting a fast-acting shutter mechanism that doesn't induce vibration to the camera.  That's a little tricky since an external shutter will have to move ~1.5" across the front of the lenses, on the order of 10 milliseconds or better.  The best candidate would be either a roller blind type shutter or a rotary shutter.  These are old-timey shutter types that aren't in use anymore, but they work.  For maximum flexibility in interaxial, one really needs to go with the roller blind design.  And it ought to be a double roller blind, so that there is a first and second curtain.

I believe Skype and some translator apps are supposed to work in (near) real time to translate audio. 

Anyone tried this?

On Saturday, August 22, 2020, 02:52:42 AM EDT, John Rupkalvis <stereoscope3d@...> wrote:

International stereo club meetings and stereo conferences can be streamed, with the caveats not only of different times, but also in some cases of different languages.   One possible workaround would be to introduce an intentional delay such that each meeting would be recorded and seen later, with questions and comments answered at the following meeting in several translated languages at times that would be convenient for the receiving locations.  I am reasonably certain that Zoom and the other virtual meeting systems could accommodate such a system.  

John A. Rupkalvis

stereoscope3d@...

There must be some other way to control the shutter speed of a gravity shutter. All objects fall with the same acceleration regardless of weight. You could adjust the height from which it falls, since dropping it from higher up will get you a faster shutter speed.  I am trying to think of wether the exposure would be different fpr the top and bottom of the frame.

Timo

Sent from BlueMail

On Aug 22, 2020, at 1:27 AM, John Rupkalvis <stereoscope3d@...> wrote:

The Sinar Norma shutter for 4x5 and 8x10 view cameras would be good to look at.  If you prefer focal plane shutters, some of the earlier sheet film cameras, like the 4x5 Speed Graphic and Graphlex cameras were fitted with these.  The problem with those was that you had to reset the shutter speed after every exposure.  Also, they were rather noisy, with a rather loud "Galump" sound every time they were fired.  Some people actually made their own, including the rather interesting double-curtain "gravity shutter" design.  The edge of the curtain was fitted with a lead weight, so triggering the shutter just allowed it to drop, the shutter speed being determined by the size and weight.  Most manufactured versions were spring-loaded.  

John A. Rupkalvis

stereoscope3d@...

On Fri, Aug 21, 2020 at 2:24 PM DaveJes1979 via groups.io <davejes1979=yahoo.com@groups.io> wrote:

I realize we have discussed this before, but for newcomers it should be noted that  "perfect synch" is achievable by the use of a common external shutter.  While there are stand-alone shutter devices on the market, I doubt that any of them would be large enough to cover the lenses of two mirrorless cameras (although I might be wrong on that).

So that means one would likely be looking at a DIY project.  While I am a man of many mechanical talents, my expertise ends where the electronic hardware and software begin.  So I was never able to get the concept off of the drawing board.

On the mechanical side, the important trick is getting a fast-acting shutter mechanism that doesn't induce vibration to the camera.  That's a little tricky since an external shutter will have to move ~1.5" across the front of the lenses, on the order of 10 milliseconds or better.  The best candidate would be either a roller blind type shutter or a rotary shutter.  These are old-timey shutter types that aren't in use anymore, but they work.  For maximum flexibility in interaxial, one really needs to go with the roller blind design.  And it ought to be a double roller blind, so that there is a first and second curtain.

The Sinar Norma shutter for 4x5 and 8x10 view cameras would be good to look at.  If you prefer focal plane shutters, some of the earlier sheet film cameras, like the 4x5 Speed Graphic and Graphlex cameras were fitted with these.  The problem with those was that you had to reset the shutter speed after every exposure.  Also, they were rather noisy, with a rather loud "Galump" sound every time they were fired.  Some people actually made their own, including the rather interesting double-curtain "gravity shutter" design.  The edge of the curtain was fitted with a lead weight, so triggering the shutter just allowed it to drop, the shutter speed being determined by the size and weight.  Most manufactured versions were spring-loaded.  

John A. Rupkalvis

stereoscope3d@...

On Fri, Aug 21, 2020 at 2:24 PM DaveJes1979 via groups.io <davejes1979=yahoo.com@groups.io> wrote:

I realize we have discussed this before, but for newcomers it should be noted that  "perfect synch" is achievable by the use of a common external shutter.  While there are stand-alone shutter devices on the market, I doubt that any of them would be large enough to cover the lenses of two mirrorless cameras (although I might be wrong on that).

So that means one would likely be looking at a DIY project.  While I am a man of many mechanical talents, my expertise ends where the electronic hardware and software begin.  So I was never able to get the concept off of the drawing board.

On the mechanical side, the important trick is getting a fast-acting shutter mechanism that doesn't induce vibration to the camera.  That's a little tricky since an external shutter will have to move ~1.5" across the front of the lenses, on the order of 10 milliseconds or better.  The best candidate would be either a roller blind type shutter or a rotary shutter.  These are old-timey shutter types that aren't in use anymore, but they work.  For maximum flexibility in interaxial, one really needs to go with the roller blind design.  And it ought to be a double roller blind, so that there is a first and second curtain.

I have one of the earlier ViewMagic viewers, which was designed for viewing over-and-under images on a 1.33:1 aspect ratio screen, such that each eye-view would then be a 2.66:1 aspect ratio (like the original 2.66:1 CinemaScope images).  These were preceded by the KMQ viewers which achieved the same 2.66:1 aspect ratio using two wedge prisms instead of four mirrors.  Sometimes there was a very slight cropping with either of these viewers when a septum was part of the image area.  When this cropping existed, it was compensated for by changing the viewing distance, again applicable to both viewer designs.  Both viewing systems were used for viewing 3-D over-and-under films, like StereoVision, on a Moviola or other editing viewer (such as a flatbed), and could also be used for viewing them on a CRT television screen of that era, as well as on a videotap monitor showing the viewfinder image of the film camera. A videotap was the output of a small video camera mounted in the viewfinder tube of the film camera. For example, I used a KMQ for viewing StereoVision 3-D on a Steadicam monitor, as well as on a split-screen videotap viewfinding monitor on a helicopter with an Arriflex 35mm film camera fitted with a StereoVision lens.  

John A. Rupkalvis

stereoscope3d@...

On Fri, Aug 21, 2020 at 6:28 PM <bglick97@...> wrote:

regarding the view Magic... as I mentioned, maybe we have different versions?  Maybe I am confusing it with  Over  / Unders I have designed and built, which the best I could do was create square images, see the attached pictures...

What I am confident of, the mirrors surely can be longer (taller) vs. wider due to restrictions of IPD, we have that other eye in the way ;)   There is not much restricting the mirror height, the taller part of the image.   My VMagic is in storage...

Try this simple test..... take your VMagic, look at a large white paper close, mark the areas on the paper the VMagic can see withOUT moving the VMagic, advise of the aspect ratio, tall, vs. wide.  It's possible the VMagic restricts the tall part by restricting the window you look into,  to make it view wider vs taller, i.e. an intentional vignette. 

report back... I have not used it in 10 years, I could have easily forgotten! 

I noticed they did make two versions of the VMagic as well, report which one you have?  When the description says to veiew wider images, is this by sliding the VMagic L/R, or slide the Images L/R.  I do see the horizontal window you look into, so you might all be right, I am thinking they intentionally provided a vignette to keep the aspect ratio in landscape format.

https://www.berezin.com/3d/ViewMagic.htm

On Fri, Aug 21, 2020 at 3:34 PM Bill Costa <Bill.Costa@...> wrote:

> [Another Bill has] written that the View Magic viewer will use tall
> images which are not ideal for 3D capture.
>
> As far as I know and I owe one View Magic under over viewer, the
> prints I am viewing are horizontally 6" wide and 4" tall. Even wider
> images can be viewed. The FOV is restricted because there are no
> lenses and the prints are far away.

I was also surprised at Bill's assertion.  The reason I got the
ViewMagic was for viewing panoramic 3D prints, for which it works
well.

...BC

Attachments:

• OU.jpg
• aspect ratio.jpg
• Eins.jpg