3D Stereo Camera Rigs and Sync

[BerndPietsch]

Thank you, Jose, for your comment. I love your photos.
However, I must add, that your footage is a professional one. In contrast, my equipment can not be professional and is for private use only.
Yes, I can make very good videos using 4 K (2 880 Pixel x 2 160 Pixel) that are sufficient for my home use, not more. First of all I have to discard some clips that I can't get sychronized and sometimes one camera doesn't start, all in all too unreliable for professional use.
But finally I can record video with a fantastic 3D depth and a very better resolution than the W3 (for 3D-photos it's OK).
Both cams plus the gimbal have cost not more than 250 €.
My intention was that currently you can't go into a photo shop and buy a 3D-cam or order it via an online web-shop. But you can still make 3D photos/videos with little money.

[josebarbera]

Thank you, Bernd

Also your photos are excellent.



On the other hand the Sony Alpha cams are not expensive at all:

In second-hand the already discontinued (also are discontinued the Samsung NX300 and NX1000 cams) Sony cams NEX-3N and A5000 (APS-C sensor and both mirrorless with interchangeable lens ) have now very low prices.

The prices of A6000 and A5100 oscilate around only 400 or 500 euros and they will decrease after the commercialization of the new Sony APS-C model (A6700 ?), just before Christmas 2018:


https://camelcamelcamel.com/Sony-16-50m ... ext=search

https://camelcamelcamel.com/Sony-Mirror ... ext=search

https://savemoney.es/asin/sony%20a5100


Obviously the Sony FullFrame mirrorless (A7 series with nine different cams) are very professional and expensive, but now, 2018, and not before, professional users can pair the best cameras ever built for make stereo photography, with the same technological level as 2D photographers. Their prices also are high for professional 2D photographers who usually do not have just only two good cameras, like us for make s3D, but ... several.


There are several dozens of Sony cams options, with prices from 350 euros (A5100) to 3500 euros (A9, interesting only for extreme sports).

Between the most expensive and the cheapest Sony Alpha cams, there are several dozen Sony models perfectly synchronized, without forgetting the possibilities, already commented, of the compact ones.

On the other hand the new and intelligent laser pendulum test (developed by Barry Aldous) has been described in the fall issue of Stereoscopy Magazin (from ISU: International Stereoscopic Union) to measure, in milliseconds or less, the synchronization between two cameras.

The length of the trace minus its height determines the laser path corresponding to the speed of both cameras.

Settings of the tests showed in the pictures:

-Speed priority
-Speed 1/50 (20 milliseconds)
-Trace of 20mm implies 1 mm in 1 second

Coincidence even in half a millimeter implies coincidence in the synchronization in half millisecond or less.

Realy a perfect and miraculous sync of the Sony A6000 rigs, showed here:

http://phereo.com/album/5bcd974c8884287b4e000002

[josebarbera]

There is a "guest post" about the possibilities of the cable manufactured by Sony (VMC-MM2) for the synchronization of its current Sony Alpha cameras, and its usefulness in stereo photography:

https://www.sonyalpharumors.com/jose-ba ... lpha-rigs/

[526e012cdf7df37b6d000002]

I'm glad i found this topic, because i have two A5100
So i just buy these two cables, connect them, and have perfect sync??
DSLRKIT E3 F-S2 (Female) and DSLRKIT 2.5-S2 (Male) ?
Even with flash?
How does it work? I have to press one shutter? Which cam is the master, which is the slave?
Burst photos are also synced?
Does it contain any electronics? And the Sony vmc-mm2?

Many thanks!

[josebarbera]

I do not have experience with flash because for my purposes the cameras have enough ISO sensitivity.

Using the cables DSLRKIT (female + male), both cameras can work as master and as slaves, Using the Sony VMC-MM2 cable you can shoot pictures simultaneously on both cameras just by operating the shutter on the main camera (the cam connected to the I-shaped plug), but operating the shuter on the sub-camara (the cam conected to the L-shaped plug, right angled) it’s not possible shoot the main camera and only one pic (in the sub-cam) is obtained.

Of course only occurs a perfect sync on both identical cams using the well know 2 steps method, in order to avoid easily avoidable unsuccess :

First step: half press (focusing)
and
second step: full press (shooting)


Burst photos also are perfectly synced. Please see these from Randy:

http://phereo.com/image/5add680ce7e564941d00012e

http://phereo.com/image/5ba5bff6e7e5645d660000ab

http://phereo.com/image/5b18a10de7e56473040000f9


Here other s3D burst photos:

http://phereo.com/image/5bcd9ab8e7e56470500001e5

http://phereo.com/image/5b2d7376e7e564602f0000d5

http://phereo.com/album/5b2d7270e7e564752f0000d3

[josebarbera]

Trying to compare only 2 variables (stereo base and focal lenght), I have made a few photos, always with the distance to the nearest object located about 3 meters (thus this third variable, the distance, (involved in the depth triangle) becoming a constant).

50% photos are shot with a stereobase of 70mm and the other half have a stereobase of 140mm. Therephore each object has 2 pics with two different stereo bases.

Of course all the photos have been edited using the latest version of SPM and the final resolution is FullHD (1920 x 1080). I have assigned to each photo the name of a Spanish city and I have uploaded all them, in alphabetical order in this album:

http://phereo.com/album/5c03c410e7e564831a0001aa

My hypothesis is that visually, looking all these photos, it is impossible to know which ones have an orthodox stereobase (50% with 7cm) and which (another 50%) have unorthodox stereobase (14cm).

If my hypothesis is confirmed, then can be proved that the excess stereobase of the current Sony Alpha rigs (mounted side-by-side), can be compensated by decreasing the lens focal length in half, as was previously commented here:

viewtopic.php?f=3&t=296&start=10


That is ... I think that following two different paths: orthodox (70mm) and unorthodox (140mm) ... both results are equal because the stereobase excess can be compensated by varying the focal length.


That all may be relevant because several facts support the suitability of the current Sony cameras for s3D :

a) The performance of the last Sony Alpha models is excellent in all possible parameters of quality: : Sensor size and quality, stabilization, tilting screen and its resolution, RAW support, color depth and dynamic range, pixel sensor size in microns, number of focus points, face detection focus, eyes detection focus, continuous shoting at hight resolution, maximum light sensitivity, max ISO whitout noise, faster max shutter, AE bracketing range, viewfinder resolution, environmental sealing etc.

b) The Barry Aldous test has proven that the current Sony Alpha cams have an excellent synchronization, half millisecond or less:

http://phereo.com/album/5bcd974c8884287b4e000002

c) Their prices are very affordable because they vary according to their characteristics between only 350 and 3500 euros (these latter only for very specialized professionals).


If... the only drawback is that the stereobase of the Sony Alpha is excessive (only in SBS rigs because using bottom rigs it can be under 70mm.) ..


... then it can be very interesting to see if:

d) Visually it is proved that this stereobase excess can be compensated by varying the focal length. That is ... following two different paths: orthodox (70mm) and unorthodox (140mm) ... both results are equal.

[526e012cdf7df37b6d000002]

thanks
i can't wait the arive of the cables

[526e012cdf7df37b6d000002]

My cables are still not here
What if i open my release and connect another microusb cable? Just like here:
http://phereo.com/image/5c03e2a6e7e5647f25000199
Will it work, exactly as with 2 cables what i ordered?
thanks!

[526e012cdf7df37b6d000002]

I found a site about electronics:
http://peterwedege.blogspot.com/2016/01/analyzing-sonys-new-multiport-protocol.html

[526e012cdf7df37b6d000002]

Ok, finally got the cables, and the sync seems perfect between my a5100's.
Even burst mode, but for some reason only the high speed.
With flash i got no sync.
I use two 16-50 kitlens. With these cam lens correction cannot be disabled.
Is it a problem? Say one cam is zoomed at 24mm, and the other at 26mm.
With the corrected image pairs, maybe we cannot make perfect stereo pairs?
I doubt SPM can correct such errors.
But will test it these days

Thanks again!