Wednesday, August 2, 2017

Adjustable Z-Bar for twin NX1000 cameras



I have designed and been testing a new adjustable Z-bar for twin NX1000/NX1100 cameras. The idea is similar to the first one I made earlier (my first bar, see: http://drt3d.blogspot.com/2016/10/twin-samsung-nx1000-for-stereo-ii.html) with a bit more attention to the details. The big attraction of this bar is that the stereo base is adjustable.

My friend, Ted Whitten, encouraged me to build this. At first, I was resisting, being very happy with the Werner body mount (http://drt3d.blogspot.com/2016/10/z-mount-for-samsung-nx-cameras.html). But then, something happened: I was ready to photograph the Memorial Day Parade in Brecksville. I had my cameras mounted side-by-side on my twin camera bar. I was standing under an electrical wooden pole. I looked up and saw the American flag, among transformers and electrical wires. The flag was being lit by the sun and everything looked just right. I wanted to lift my camera and take a picture of the pole and flag, but I could not, because I did not have a normal stereo camera. Using the side-by-side cameras would not have worked because I was too close to the subject. I needed normal camera/lens spacing. But I did not want to disturb my setting (it takes time to switch from side-by-side to the body mount), with the parade starting soon.

At that moment, I wished I had a z-bar with adjustable stereo base. So, I decided to build one. While Ted was visiting, we worked on a pair of bars. I figured out the basic dimensions and made two bars, one for Ted and one for myself. I tested my bar and it works fine. Now Ι got to the point where that’s all I use. So, I decided to start making this bar available for others.

Here is how I make the bar

I start with a piece of aluminum channel, 3" (tall) x 1" (wide) x 0.125" (3mm, thick). This material was recommended to me by Bob Karambelas, as described in the previous blog. It is the same piece I used for my first mount, and Bob for his, before we knew about the body mount.

I buy the aluminum channel in 24" pieces, and then cut it as shown in this diagram:




I cut a piece about 9 inches (230mm) long. I decided on this size because this is the length of two cameras touching each other. This way the bar will not spill out of the cameras when they are at their closest point.

I then remove two pieces, based on two important dimensions: 1) The center column is 20-22mm (I started with 20mm, now I favor 22mm). This column is in the back and does not cover the screen when the cameras are touching each other. It serves for both structural strength and camera alignment (when the cameras are close enough).  2) I leave a “step” of 8mm high. This is the step that the cameras rest on, and it helps to align them. This is tall enough to help align the cameras, but not too tall to hinder the two lower buttons or the screen.

After removing these two pieces, I need to drill holes and a channel at the top and bottom arms. I drill a hole 34mm from the center line and 15mm from the back step. These dimensions are dictated by the location of the camera tripod socket. My first design only had this hole and the cameras were at a fixed minimum spacing (touching each other). For this new adjustable design, I create a channel about 65mm long as shown in the schematic.

There is only one important detail left:  The distance from the top to the bottom is 76mm (total height of the channel) – 2x3mm (thickness of each arm) = 70mm. The distance from the bottom of the camera to the center of the lens is 33mm. So each camera must be raised by 2mm for the lenses to be aligned: 33mm + 2mm = 35mm, right at the center of the 70mm z-bar spacing.

To raise each camera by 2mm, I use a rubber washer for each camera. This is 2mm thick so it raises the camera, plus it holds the screw in place when the cameras are removed. The only issue with the rubber washer is that it hits the bar and the cameras do not slide smoothly. Also, it could be contributing to some misalignment. I am now experimenting with a piece of plastic. Check later for updates on this.

Update: I tried a piece of hard plastic and the cameras slide smoothly and the alignment is maintained (the rubber was being compressed, the hard plastic is not). It is a piece 20x60mm, with a hole drilled. It keeps the screws in place, raises the cameras, maintains good alignment. That's the way to go now.

The final product, with cameras mounted, looks like this:




(Note: This is my first bar… The back column is not straight. I am trying to do a better job since then )

Regarding the tripod sockets, there is one at the top and one at the bottom. I positioned these a bit off center so any screw thread from a tripod or camera grip does not hit one camera. At first, the z-bar was totally symmetric so either side could be the top or bottom. In my last batch I left one mount screw standard 1/4", but made the other one 3/8" for two reasons: 1) In case one needs a 3/8" mounting socket. 2) I added a 3/8 to 1/4 inch adapter. The adapter is made out of stainless steel so it is more durable than the easily deformed aluminum. I recommend using this side as the bottom.

Advantages of the Adjustable Z-bar

Compared to the body mount, this z-bar has two advantages:

  • Adjustable stereo base: This is a big one. One way to think about the stereo base is in multiples of the standard stereo base, which is around 65mm or 2 ½ inches. Let’s call this SB (Standard Base). The body mount only has one stereo base, SB. This z-bar goes up to 3xSB (about 8 inches or 200mm). 

Here is a quick way to get three different stereo bases, in case you like to bracket stereo bases:
  • With cameras touching: 1x SB
  • With one camera extended: 2x SB
  • With both cameras extended: 3x SB




  • The cameras can be removed from the mount very easily (unscrew the screws by hand). There is no need to take off the lenses and no tools are required.




Some other points:
  • Any shoe-mounted flash will work since there is no mount to interfere over the R camera.
  • The batteries and memory card can be accessed by simply sliding each camera out (see picture below).
  • There are plenty of standard 1/4" mounting sockets. One at the top, one at the bottom, plus the two screws that hold the cameras have a socket at the bottom. 
  • Finally, the 8 inches total stereo base of this rig is the same as my 12 inch twin camera bar. So, this z-bar simplifies things. Not only I do not need to carry the 12 inch bar, I also get all my stereo pairs in similar format, which simplifies processing.






Disadvantages of the Adjustable Z-Bar


  • It is not as well-aligned as the body mount. When the cameras are touching, alignment is good enough. When they are separated, alignment gets worse. I am working on this and will report back later, after I try other ways to raise the cameras by 2mm. This misalignment is not a practical problem for me because StereoPhoto Maker aligns the images very well.

  • It does not look as elegant as the body mount. I am still learning how to machine these. I am now working at making smoother curves, but these bars do not look nearly as elegant as the bars I have from Co Ekeren. But, they work.

One last note: The standard one-piece remote cable, is not long enough for this bar. I have ordered a set of longer cables that will work. But I have found advantages in using the twin remote: The main one is that you do not have to touch the cameras, so pictures with slower shutter speeds can potentially be sharper. 

My standard configuration for these cameras now is this adjustable bar, plus the twin remote.  Plus my favorite camera grip. This is how my rig looks right now (with 20mm lenses):






1 comment:

oktayakdeniz said...

George, the critical section is the middle coloumn.
After several uses, mine got broken and I had to repair it by adding a patch.
But the cross section of the profile I have used is only 2mm.
If I were to do it again, I would increase the width of the coloumn to 4cm at the expense of
covering part of the screen of the inverted camera.