Stereo rig and base distance

Hello 3d enthousiasts,

I have a question. I have 2 sony a6000’s and want to buy a stereo rig. They are connected with a sony sync cable vmc-mm2 with a difference of the shutterrelease less then 20 microseconds which is very good for pictures (not movies). With a normal rig I have a stereobase of 143mm and if I make a Z-rig (one camera upside down) it will be 120mm due to the space for the cable. Will the effort for the Z-rig (24mm less base distance) be visible in a positive way? Or is this method not good anyway because the human eyedistance is 65mm?

Thanks, Coen

The human interpupillary distance is irrelevant in this area of interest.

As a basic rule, the stereo base is recommended to be 1/30 of the distance to the closest subject in the frame, for subjects situated at normal to long distances from cameras, about 1/10 in the case of macro 3D photo, and everything in between depending on particular situations.

Thank you for your answers. I think the base is important to avoid a lilliput effect (our brains are used to 65mm) but when I use the stagger method how do I correct for the difference in distance? One lens is 50mm closer to the subject or is that negligible?

Coen

I chose to arrange the two cameras vertically bottom-to-bottom and thus keep stereobase within 55-75mm.

Then I use a wider lens and crop to 1x1 or so.

Thank you, I’m going to use your idea. The 16mm range from the back camera doesn’t see the front camera with 16-50 standard lens. Great.

Oleg, I have a question.

your solution has the most little base range.

But do you have pivot monitors or do you cut something from your images to make them squared?

No, the cameras stay parallel, and I look only on one display.

I can blindly feed the two images to StereoPhotoMaker and use its auto-alignment to find the "common" areas.

Conceptually it equals to the "cut" option.

It was my father's idea. I was originally locked to stereo-should-be-horizontal paradigm.

Now I realize that being square or slightly vertical is actually more usable. Just think of parallel viewers, etc.

Brian F Flint wrote:

For objects which are around 3 metres in front of the lens , the 50mm means one camera will have its image 1.6% larger than the other camera's image. It is normal to make alignment corrections between left and right image using software on a PC. This is free software - StereoPhotoMaker. It can easily adjust for the different in image sizes and other difference such as tilt which occurs between the two cameras. There are also manufacturing differences between lens which can result in different image sizes.

What about the size of distant objects? Still 1.6% larger?

coentje wrote:

Hello 3d enthousiasts,

I have a question. I have 2 sony a6000’s and want to buy a stereo rig. They are connected with a sony sync cable vmc-mm2 with a difference of the shutterrelease less then 20 microseconds which is very good for pictures (not movies). With a normal rig I have a stereobase of 143mm and if I make a Z-rig (one camera upside down) it will be 120mm due to the space for the cable. Will the effort for the Z-rig (24mm less base distance) be visible in a positive way? Or is this method not good anyway because the human eyedistance is 65mm?

Thanks, Coen

Try decreasing "sleep time" or "monitor off time" (I don't remember the right expression) in menu to the minimum value (10 seconds?). Put both cameras into video mode. Wait till both cameras enter sleep mode. Slightly press shutter button when they are connected with a cable. They both wake up. After that focus and start video. Check synchronisation.

https://www.dpreview.com/forums/thread/4532790#forum-post-64946027

Brian F Flint wrote:

This method of getting the two lenses closer is not perfect. In practise I find it does not cause a significant problem.

Interesting, for me even 0.5% height difference is way too much for comfortable vision. Apparently I am not a "hardcore stereoscopist"

Seeing a perfectly aligned image or an image with a small height difference is like night and day for me. The latter always causes some strain in my eyes.

The optical centers of the two lenses can be perfectly aligned. I do not see from where is the problem of vertical misalignment.

Yes, that's theoretically possible too, if one camera is partially pushed in front of the other. Unfortunately StereoPhoto Maker does not know how to solve that properly, and I am not keen on using Linux SW for that (there is a program that does it perfectly).

Also, one camera in front of the other and perfect alignment (note: Linux) leads to a pretty limited horizontal view in 3D and muddy parts of the image. This has to be taken into account.

Using one of the cameras in an inverted position (upside down) is a much better solution.

For smaller inter-axial distances a beam-splitter rig is needed.