Tuesday, February 28, 2012

Review: Edelkrone Pocket Rig

There is an update to this post on the hinge issue of the pocket rig. You can read it by clicking here.

The Edelkrone Pocket Rig.

Although this is a VFX blog I also like to talk about film equipment. Especially when it is the cheaper kind for the Indie film makers. Edelkrone is a Turkish company and has come out with some nice new rigs and the Pocket Rig is definitely a new concept in the world of camera rigs.

I have been looking for a DSLR shoulder rig for quite some time now and when I saw the demo video for the Pocket Rig I was immediately enthusiast about it's size and portability. You can easily order the Pocket Rig from the Edelkrone online shop and currently it sells for $299. I also ordered the handles which are $149 and fit perfectly on the bars of the rig. It is delivered by DHL and when the items are in stock your order will arrive in two days (when living in Europe). Take notice that these prices are without taxes and VAT. Expect to get a bill from DHL. Belgium for example ads 21% VAT.

The box and its contents.
The extra handles.

The box of the Pocket Rig is made of sturdy carton board and contains foam to protect the rig during transport. It holds the rig in its collapsed form and an allen key but no manual. Then again, when you have watched the demo movie from Edelkrone once, it is not hard to figure out how it works. The extra handles came disassembled in bubble wrap and are easy to assemble.

The Pocket Rig is made out of black machined aluminum. Whit its 550g (or 1.2lb) it is not very heavy but it does add 30% extra weight to your DSLR which is definitely noticeable. In its collapsed state it is not much bigger than a battery grip. There are some rubber pads on top which prevent the rig from sliding around when it is attached to the camera and protects the camera from scratches. The screw for attaching the camera sticks a bit out and is attached to a big wheel which sticks out on the front and the back. This makes it quite convenient to screw the rig to a DSLR. I also tried to screw it to a Panasonic HVX 200 which is quite a bit bigger than a DSLR and it did work nicely.

The stock folded out.

It is easy to unfold the stock and fins which are hidden under the base plate. The fins can be used to push the rig against your shoulder or it is possible to use them as a clip on a belt when you need to shoot from the hip. The stock itself is a bit longer than 10 cm (4 inches) but can be extended to 30 cm (a foot) with two screws. This way it is possible to watch your DSLR display directly or to attach a viewfinder which you can press to your eye.

Unfolded rods.

There are two folded industry standard 15mm rods underneath the stock. These rotate on a hinge and can be locked into the forward position with a ball bearing locking system. It is possible to mount an extra handle and a follow focus from any brand at the same time on these rods but they do seem a bit short to add a complete matte box system on them though.

Under the rods there is an extra plate with a hole which can be used to attach the rig to a tripod. Together with the rods and the follow focus it becomes a very powerful combination which usually only more expensive rigs have at their disposal.

The Pocket Rig with screwed on handles.

I did get some extra handles as mentioned above. These are also made out of machined aluminum and have good rubber grips. They can slide along the rods and each handle can rotate a full 360 degrees so it is highly adjustable. I noticed that the handling of the whole rig becomes more stable with these handles.

My opinion on the Pocket Rig
I had the Pocket Rig with handles trough a test run when shooting for a project with my Nikon D7000 and had also other people have a go with the rig.

I applaud it's extreme portability. It is indeed very small and easy to stow away in a regular backpack. Although the weight is noticeable it is light enough in comparison to the rest of the kit and it does add a bit of stability to the whole. Since it is made out of thick aluminum it is also very sturdy and can withstand bad handling quite well although I do recommend to be careful as the camera on top will not like such treatment at all.

The whole rig with a camera attached to it.

The rods are absolutely great. This is what makes the Pocket Rig stand out. When not needed they fold away very neatly and are hardly noticeable but folded out they add great functionality. Handles or a follow focus are the obvious add-ons but there are more options like a monitor or even a matte box. Do mind that they are not very long so if you got a big lens like the picture above then the matte box is probably a no go. It possible to unscrew them to add longer rods instead but then it defeats its portability feature.

There is one feature missing in my opinion. The hinge of the stock is on the right hand side which means that when you press the rig hard against your shoulder it has the tendency to collapse to the left. Something like a ball bearing locking system as the rods have would have been convenient. Time management is essential on a shoot and you don't want to redo a perfect take because the rig just collapsed at the wrong time. It doesn't mean the rig becomes unusable but you do need some training to get used to it, then again all rigs need some training anyway.


I think this is a great product and although it is not the cheapest it is reasonably priced. Just a pity that the hinge has no locking system as that would make it perfect.

Update on the hinge (10 March 2012)
My biggest issue with the Pocket Rig is that the hinge is a bit loose and it that it has the tendency to collapse when firmly pushed against the shoulder. While posting this blog in a pocket rig thread on the dvxuser.com forum it came to my attention (thanks to Nick_K for spotting this) that there is a solution to this problem.

Three screws to adjust the hinges

In the picture above you can see three black screws of which two of them solve more or less my problem. The hinges become much harder to move when tightening these screws. Screw 1 is responsible for the vertical rotation. Screw 2 is used for the horizontal rotation. Out of the box screw 3 was already tightened and is not needed to control the rotations. The allen key for tightening the screws is provided as you can see in one of the pictures above.

Although I am happy that there is a remedy I have two remarks on this issue. The screws are in logical positions so you can figure it out by yourself but I have the tendency not to experiment too much by unscrewing things. It would have been great if there was a little manual or at least a link to an online pdf file to explain this. The second remark is that when you tighten the screws too much it becomes harder to fold the whole rig so it is important to find a good balance there.

If you ordered your rig before 01/01/2012 it is likely you will not have this option. The good news is that Edelkrone will send you a free upgrade piece. Check this link to order it: Pocket Rig upgrade

The Edelkrone website
The Pocket Rig on Vimeo

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Tuesday, February 14, 2012

VFX Back to Basics Series: 3. What is tracking and Match Moving?

This is part of a series on the basic elements of Visual Effects. Each post will talk about a certain element which is one of the basic bricks used for building VFX shots.

In this third post I will talk about tracking and match moving.

some of the tracking markers which I use on set. Eric Alba designed these markers.

We can divide tracking into two categories. There is 2D tracking mainly used for adjusting live action in the comp and 3D tracking for adding 3D generated imagery to a shot. The last category is also known as match moving. I'll start with 2D tracking as it is the base for the 3D kind.

Very often compositors need to follow certain objects or shapes in a shot. A good example is a billboard with some commercial message which the client likes to have replaced by something of his own. If the camera doesn't move then it is very easy to place the new image over the billboard and we can call it a job well done. Most of the time though directors do like to move the camera around to make those money shots. A solution would be to move the new image manually frame by frame to keep up with the movement. This is very time consuming and not too pleasant for the VFX artist. Instead we use a tracker and let the computer do the tedious work for us at a much higher speed. Another common use for tracking is to stabilize the backplate. Sometimes the movement of the camera is unwanted and instead of trackers following the image, the image tries to follow the stationary points. This is slightly oversimplified but brings the point across. Have a look at the image below and I'll explain how a tracker works.

A typical 2D tracking point with the tracking center and two boxes for the search pattern.

The main components are a tracking point, right in the middle, and two boxes around this point. The central tracking point is the coordinate of the tracker on your image. The smaller box is is the region which the computer tries to match when comparing frames and the bigger box is the search area in which the computer will make its search when trying to find the match for the smaller box. Choosing the location of your tracker is rather important as the computer needs a pattern which it can recognize. Placing the tracker on a solid color for example is bad as there are several positions on the image which will generate a match. Use corners of objects or high contrast pixels which can be provided by carefully placed tracking markers (see image at the start of the article).

Example of a bad tracking point. The pattern in the sand is not contrasty enough and the tracking point will probably start sliding when the computer tries to find a solution.

Once the computer has figured out the motion path of the marker it is possible to attach an image to that marker. The image will now follow the motion of the backplate. If the movement is only a translation then a single tracker is enough. If the backplate also rotates you need a second marker which combined with the first marker will find you the proper rotation. Stabilizing a backplate which was shot handheld is a good example where you need at least two points. If there is also a scale or perspective change then it is best to use four points. Adding more points usually gives better results.

Let's move to the 3D realm again and I'll show you how we can use the above technique to our advantage to extract three dimensional information out of a two dimensional image.

The world around us is a three dimensional space but when we shoot film or pictures that world is converted to a flat image. In my previous post I was talking about how convenient it is to use 3D modeling for Visual Effects but how can we place those objects in the scene if our source is only a two dimensional image? Luckily some smart mathematicians came up with Photogrammetry. This fancy word means that we can deduct the measurements of the objects in the photo when we know at least some measurements on a couple of objects in the scene that we are photographing. With these measurements we can rebuild the whole scene in a 3D space.

While filming with a moving camera there is an added benefit. When seeing the same objects from two different points of view and two frames from a shot with moving camera provide exactly that, we can use the power of triangulation. This concept is also called parallax. The more depth there is in the scene the better this will work as objects on different distances will appear to move different distances. An extreme example of parallax is watching the moon while sitting in a moving train. The trees close to the track whiz by but the moon doesn't seem to move at all.

A typical automatic track with lots of tracking points chosen by the computer.

3D tracking is done by the help of specialized software. Matchmover, Boujou, PFTrack and even NukeX can do the job quite well. These programs can track a shot automatically but if the result are not satisfying then it is possible to add tracking points manually. Same rule applies here too, more tracking points give a more accurate result as all the little mistakes get averaged out. The tracking points do have a quality value added to them which is compared to the average value. When they exceed a certain error margin they will be dropped from the results. It is also possible to remove an automatic tracking point manually if you think it gives bad results.

The ultimate match move is to track actors and their movements such as facial expressions. By putting a grid on the actors face it is possible to follow the facial features and then use them as a base for a CGI face which will replace the original face of the actor.

This concludes the third part of the VFX Back to Basics series.
Make sure to subscribe (at the top) or follow me on Twitter (check the link on the right) if you want to stay informed on the release of new posts.

In this series:
1. What is rotoscoping?
2. What is 3D modeling?
4. What is 3D animation?
5. What is shading and texturing?
6. What is lighting and rendering?
7. What is matte painting?
8. What is compositing?

Useful links:
Eric Alba's website.