New CPM Follow Focus

[CPM Camera Rigs]

Hello all,

This is our third and what we believe final design/proto type of our belt style follow focus. It uses a gear box of our own design that features 4 ball bearings on the cross shafts. Plus a roller thrust bearing on the main shaft to maintain preload. We use a couple of follow rollers to 'pinch' the belt into an hourglass shape. This makes for better contact around both the lens and the drive hub. Also in helps locate some of the tension inward on the belt rather then simply 'tugging' on the lens. Has a little over 1" travel in the arm, and of course additional/longer belts can be added for larger lens set-ups. Belts run about $7-$10.00. Has the standard cinema square port for whips and arms, which we will be designing and making to go along with the FF unit. Price in its current configuration is $399.99. An interesting item that we added is a side grip for those that shoot alone and want the ability to stabilize a shoulder rig while still rotating focus. The side grip is easily removed. Looks like about 3-4 parts to be made so 3-4 injection molds to be built. It generally takes us about 1 month per tool, but winter is usually a slow time so we might be able to run multiple tools through the tool room. Maybe 2-3 months away from production parts.

Happy Holidays,

Steve

http://www.cpmfilmtools.com/Carbon_Gear_Head_s/2.htm

 

[blodbath]

Really interesting design, do the tension rollers unlock to allow for easier lens changes?

 

[CPM Camera Rigs]

Really interesting design, do the tension rollers unlock to allow for easier lens changes?

The unit slides forward and back similar to a geared style (which we will also be offering, using this gear box and pieces). But to tell you the truth what I have been doing with the proto type is just slipping the belt off the rollers. This 'un pinches' them (for lack of a better word) and puts slack in the belt so you have room to move around. R&R the lens and if the size is similar on the new lens you just slip the belt back on. So zero adjustments to make. Otherwise there is about 1" of room in the slide and of course other larger or smaller belts if the lens is drasticlly different in Dia.

Steve

 

[photonashville]

Some constructive criticism.

The knob diameter appears to be very small, a larger diameter knob can help focus pulls greatly, you can get more of you hand around it, instead of just finger tips. I prefer a beefier handle and I read that being a preference from other users.

The price point seems high for the construction. Take for instance the DFocus, it's very inexpensive yet extremely capable and standardized from the port to the use of lens gears, namely any brand of gears will work with standard gear pitch.

A belt drive is a slow and cumbersome method for lens changes. At present only CPM and Half Inch Rails goes with this concept, maybe there is a reason more don't go that route.

Think about adding a marking disc.

How much rotation do you get on the lens focusing ring with one rotation of the follow focus knob? It appears you would need to rotate the knob several full revolutions to get full focus pull on such lenses like Zeiss, Canon FD and other long barrel focusing lenses of 200-270 degrees because the very small drive hub diameter.

 

[CPM Camera Rigs]

Thanks for the feedback, always appreciated. The two items not included in the proto type picture are a magnetic marking ring and also hard stop pointer, its included just didn't make the picture. So we have you covered there. We kept the knob small so we could fit a grip under it to allow both holding of the grip and rotation of the knob. From the feedback on our testers that seemed to be the most preferred size. Plans also call for a set of whips and crank.

For lens changes you would be surprised. The belt was an option we thought had not been explored. Not sure why it’s not popular, but CPM has been built on a foundation of being a little different. Since day one we were told that no one would want a composite rig. Aluminum and stainless is all anyone would want. The popularity of the rigs blew me away. Soon after selling our first hand held units we came out with a shoulder design that held the camera under the rails. We where told that having the camera under the rails and inline would never work. Again and again, we were told offset and stick the camera above the rails. So we came out with the Sidewinder at the same time as the Bulldog rigs. The Bulldog out sells the Sidewinder nearly 2:1. So under slung and in line is actually very popular. So when it came to the follow focus we knew we would need both a geared unit and a belt unit. Which will be more popular? I have no idea but it will be interesting to find out.

I'm surprised that you think $399.99 is a high price. The gear box is completely designed from the ground up, contains 4 roller bearing, two thrust roller bearing and is spring loaded on the main shaft to minimize back lash. Dfocus with a couple gears is about $200.00. We are leaning towards a zip style gear right now for our geared version. In that configuration we’ll be about $249.99 with a couple of zip gears. Made in the USA with a lifetime replacement warrantee. I thought the price was inline with the balance of our other gear.

Steve

 

[blodbath]

I think the 399 price point is about right. A good selling point of the belt driven one is to maximize the focus pull range on AF zoom lenses that have ~50 degree focus throws. On my Tamron 17-50 I use the D|Focus and still have issues hitting focus because of the short throw.