Follow-focus (English version)

A follow-focus is a system which allows control of the camera’s focus ring without touching the camera’s body nor the lens barrel itself. Thus, the risk of inadvertently moving the camera while changing the focus is greatly reduced, and the focus can be adjusted by someone else (the “focus puller ) ”than the camera operator himself, who is free to concentrate on the framing.

On a shoot, all professional cameras are equipped with a follow-focus, which is easily recognizable by its large white and black adjusment wheel right next to the lens barrel. Discerning amateurs who wish to do things right may also take advantage of this extremely useful tool.

Useful for what ? Well, mainly for “racking focus”, i.e. quickly changing the focus point from your talent’s face to some object in the frame that you need to draw attention to. Combined with the very shallow depth of field provided by cinema lenses, this technique of racking focus is widely used. It is more difficult to achieve in video but is very desirable as it is a classic component of the cinematic look. Some critical elements in obtaining shallow depth of field include setting the camera as far away from the subject as possible, and using the longer end of the lens and a wide iris setting. In such a case, achieving accurate focus on various elements within the frame demands precision and concentration, and the main camera operator is not able to do that effectively... not to mention, of course, the case when the camera is moving on a stabilizer !

The follow-èfocus’ main downside is, as often, its price. The German vendor Chrosziel, widely reputed for the quality of its products, have been selling for several years a model (the DV Studio Rig) suited to, inter alia, the DVX100 cameras, at a price close to 1500 euros... That is extremely expensive, and difficult to justify in spite of the obvious quality of the design and manufacturing.

Fortunately, others are beginning to launch similar products at much more reasonable prices. Amateurs are also entering the arena, with a pricing policy in line with the means of many independent filmmakers, and I’ve chosen to test and review here one of those products, made by Tim Ovel under the name indiFocus. Marketed for less than 300 dollars in its basic configuration, the indiFocus deserves our particular attention as it is designed as a versatile system able to work with many cameras and lenses, including still photography, 35 mm lenses of the kind one would use with an adapter such as the mini35.

But enough preliminaries : here goes the account of my step-by-step experience with the indiFocus.

Off to not such a good start, my first indiFocus arrived seriously damaged by UPS :

Bottom view of the gearbox : damage sustained in transit
caused the gearbox to be bent out of alignment

On the occasion, Tim Ovel, quite well known on the Internet for his kindess and his helpfulness, did the right and gentlemanly thing and shipped me another complete indiFocus right away. That one arrived safely and in good condition.

The indiFocus includes the following elements : the main assembly with its rod mounts, angle bracket, gearbox and small green marking post ; a focusing knob complete with hard stops (not shown on picture below) ; two toothed gear modules (24-pitch and 32-pitch), the use of which we will describe below ; one black friction wheel ; and a “whip” which acts like a kind of wired remote control for focusing the lens.

Before you can use the indiFocus, you must have a baseplate for the camera, equipped with twin 15 mm (standard size) rods such as those used for a mattebox. I personally use this system, made by Chrosziel especially for the DVX100 camera :

Tim Ovel doesn’t sell this equipment, which can be bought from many different vendors besides Chrosziel. Cavision is one such vendor, but there are others.

The first thing to do is to place the main assembly on your mounting rods, then to assemble the focusing knob. WARNING : the tightening screw is designed to be off-center and will not easily tighten both sides of the indiFocus’s rod mounts equally. You’ll have to carefully “catch up” by hand to make sure that both sides of the rod mount are similarly tightened over the rods ; if you don’t, the whole system might end up misaligned, or slip, or be otherwise unable to always control the focus on the camera. Then, attach the camera to its baseplate :

Once the camera solidly in place, I first decided to try the friction wheel. This wheel is one of thr strong characteristics of the indiFocus : when pushed (tight, but not too tight) against the focus ring of the camera, it is designed to make it move by friction without any other accessory on a wide variety of DV cameras... provided that it works, and that the “grip” is strong enough to prevent slippage in any direction, while retaining all the desirable “buttery smoothness” inherent to a quality focus ring such as the DVX100’s.

To achieve that, the indiFocus allows you to move the whole assembly laterally (in or out) to set it closer (or not so close) to the camera’s body. Thus the friction wheel can sit in an adequately close position with respect to the camera’s focusing ring and provide a good grip for the friction wheel.

At this point, however, I had a bad surprise : once in place, the friction wheel sits right next to the lens cap, 3 or 4 centimeters away from the focusing ring ! On this Chrosziel baseplate (which is the one that comes with the classic 4 x 4 mattebox referenced 411-53 PK), it looks impossible to move the camera forward. Likewise, the rods cannot be moved backwards because they hit against the baseplate itself...!

The same issue obviously arises when you substitue one of the toothed gear modules
to the friction wheel

Informed of the problem, Tim Ovel, resourceful as always, immediately thought about designing and machining a special workaround solution in the form of a new mounting bracket. In the meantime, and in case of emergency, he suggested to install the follow-focus on the right side of the camera, as shown below. This setup is not a viable long-term alternative as it forces me to place the system at the very end of the rods (decidedly a tad too short, Mr Chrosziel !), which will prevent me from installing the mattebox, when both accessories are supposedly designed to work together. But at least, it allows me to verify that the friction wheel, once properly adjusted, does indeed control the DVX’s focusing ring in an adequate manner.

I did notice a slight play as I used the focusing knob. It did not seem to come from the friction wheel, whose grip on the camera’s rubber focusing ring seemed good, but rather from the inner workings of the gearbox. However, since there was no discernible play when I looked at (and closely listened to) the gearbox prior to assembling the knob and frcition wheel, the play I detected could be attributed to insufficiently tightened Allen screws, as I may have been overly careful during my first assembly attempt. All this will require further testing once Tim is done with his “workaorund” solution.

While I wait for him to wotk his magic, I tried the black geared ring that is included with the indiFocus, and which is supposed to fit around 35 mm lenses, for use with a mini35-like adapter.

Three Allen screws are designed to be driven through this ring, whose inside diameter is approximately 73 mm. I tested it on the following four Nikkor lenses successively : 50 mm, filter ø 52 mm ; 35 mm Perspective Corrector, filter ø 52 mm ; 35~70 mm zoom, filter ø 62 mm ; and 100~300 mm zoom, filter ø 62 mm. The pictures below show the results of my tests :

To summarize, this ring worked fine on three of the four lenses. Only the 100~300 zoom proved slightly too wide for it to fit around, even though its filter diameter is the same (62 mm) as the one on the 35~70 zoom lens. Most Nikkor lenses being smaller (especially the wide angle ones that are more likely to be used together with a mini35-like adapter), that ring should work in almost all cases.

There is, however, another potential downside to the use of this ring : on some lenses (the very widespread 50 mm, for example), when your turn the focusing ring, it moves forward and backwards several millimeters. On other lenses, the focusing ring itself does not move, it’s the part of the lens in front of it that does. Will that cause the toothed ring to become misaligned and stop operating correctly ? Could this phenomenon damage the focusing system of the concerned lens ? This, as far as I’m concerned, is still to be determined.

It took some time to write this second part as Tim Ovel, designer of the indiFocus, had to modify some of his system’s components in order to get them to operate correctly with the DVX100 B and the standard rods supplied with the Chrosziel 16:9 mattebox.

I wish to underline that Tim has been very helpful and cooperative in this whole process, and I want to thank him once again for his customer service-oriented attitude.

The modifications he made concerned longer rotation axes for the friction wheel and both toothed gear wheels, as well as a longer support bracket, as illustrated on the pictures below :

Thus modified, the indiFocus can be installed correctly and operates in a perfectly normal manner.

Like the friction wheel, the toothed gear wheel meant to control focus via the Century ring can now be positioned correctly with a good “bite” :

This problem can be remedied by positioning the white plastic wheel and the Century ring closer to one another, but then they may get too close to each other, which will make the whole system harder and less precise for the focus puller to operate.

Another issue is that, when the focusing knob is perfectly in place, it prevents the LCD screen from opening completely. This is minor, however, as the screen can be deployed almost all the way :

There remains one last issue to address : when one turns the focusing knob alternatively in one direction, then in the other (such as when one executes a rack focus move), there is a significant “play” or backlash in the knob, which means that the knob needs to travel some distance before “getting a grip” again. This phenomenon is rather uncomfortable and doesn’t allow for racking focus in a totally reliable manner... It’s a bit like having some play, or backlash, in the steering wheel of your car when driving on a twisting road !

After multiple checks, the custom-made components of the indiFocus were cleared of blame, as the culprit appeared to be the internal workings of the small gearbox itself. This is made by a British company, probably with machining tolerances a tad too high, which entail perceptible consequences when using the system.

Having reported those findings to Tim, he suggested I might had received a bad gearbox and sent me a new one. A certain amount of backlash remained with the new gearbox, but much less pronounced than with the previous one, and in practice, I don’t think it will impair the use of the indiFocus.

Conclusion

In conclusion, the really reasonable cost of this system must be underlined, as well as its versatility, as it can be used with the factory-issue rubber focus ring of the DVX, with a Century Optics focus ring, and also with most 35 mm still photo lenses on a mini35-like adapter.

The fact that some components of tne indiFocus are not machined or glued to industrial-grade perfection is, in my opinion, a logical consequence of the overall pricing of the system, which does not mean to compete with professional products in the 1,500-dollar range. As it is, the indiFocus allows a vast number of budget-conscious filmmakers to have access to a physical remote control of the focus, usable by a camera assistant, and which does the job in a satisfactory manner, in spite of some minor shortcomings.

Version française | French version

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