"What's so hard about a DIY Follow Focus? "

It is hard to make the gears with no backlash. Learned from experience:
http://p200.ezboard.com/fhomebuiltst...picID=29.topic

But if you find the gears ready made, of high quality...

Good show, very good job. Bravo. Gears are not hard to find (here). To have them in place without play is harder. Add two more gears in the equation (to get the reduction that you want) and... you are there. (didn't want to do it but I had no choice) One tiny problem: if another lens does not have the same outer diameter..... it will not engage or not fit....(given that FF gear relative to lens does not change/adjust) For one lens only though is PERFECT. BRAVO!!!

...

It was fun, though! :)
gears placed at 90degrees are easy to tune, but I had to leave some room for the rough teeth to move...

It is puzzling how you manage to synchronize the two small cameras with the focus ring of the lens, in you device...

I did not do it myself. A very gifted and dedicated programmer (of the same BG!!)wrote some 3000 lines of code over 5 months to "learn the motors" to respond to the lens movement (one way for one and backwards for the other...tested the distance intersection with lasers....analyzing the distance spread on many Zeiss/Cook lenses.....(long story but F U N stuff)

I thought about another existing 90° mechanism. How about a guitar tuning mechanism. Or maybe on for a contrabass or something.

http://www.qtcgears.com/e-store/DPGears.htm

Bottom left: Worms & Worm Gears, is exactly a guitar tuner.

yes......but are you changing careers?
is it not 3 or 4 more suitable for FF?
Could you rack from one end to the other of the lens in one second using the worm gear? (without a motor that is)

Dan, you'd better tell me. I was just wondering what could be used and is ready made (and not expensive)
So if you turn the first axes, the second one (after 90°) should turn in the same amount, or more?

"Dan. You’d better give me a fish and don’t teach me how to fish"....
It is all a matter of ratios.
What is the gear diameter on the lens? How much is active (out of it)?
What is the gear diameter on the engaging gear?...
In how many turns should I turn from close to >< (infinity)?
In one turn or less.
Say you have a 90mm dia on the lens and close to >< is spread on 180 deg (so, only half) Equivalent dia of the lens is? 45mm.
Now, if your engaging gear was 45 mm dia, you would need a 1:1 ratio in the miter gear. Right? But if you do not have the exact above figures, how should I know what would work to lead you to the desired result? Start with gear on the lens and the engaging gear of the FF, the rest will follow. Now you can go "fishing"....
If the two lens (filming and viewfinder) were counter rotating from close to >< you could figure two diameters that will engage with each other and keep the distance in sink (but that would be toooo much to calculate...)

Can you make that a fried fish instead?

I was just asking stupid questions find a way for many people, not only me(I have a weird setup anyway), to get the basic elements of a FF from ready made stuff. So the best thing to look for is probably a 1:1 ratio (It looks like that's what Cosmin used)
I also wonder how a professional FF deals with different lenses?

>>>>>Can you make that a fried fish instead?<<<<<
Sure can.
what would you like on the side signore? *smile* and relax, no pun intended...hey?*smile* and enjoy the ride.
>>>>I also wonder how a professional FF deals with different lenses?<<<<<
Derz an artuc.... arctic.... hmmm ... an arm... that moves in and out to reach different lens diameters.
Recent lens designs like Zeiss superspeed have the same dia at the same distance from the mount (aint that swell?)*smile* life is short.
(......hmmm....artuculite?)
Oscar, der aint no stupid questions, OK?
Is just that there are too many variables to provide a "formula" that works. I forgot to add, you should consider the distance from "rods" to lens as well. (the nightmare's just B gun) I want to make sure you understand I admire your 2 camera idea and implementation as well as all the hard work involved to make it happen. I did not make fun of you OK?
Just average, "no name" entertainment...*smile* (I like that)

Right! Make that "Dan, you’d better give me a fishing rod in stead of a fish" ...maybe I can make a FF out of it.
Many thanks for your replies, you know a lot. I'll be experimenting with this in a few days. For me, thats always the best way.

first i think that Dan Diaconu's work is amaizing , and i really wan t to try to make a FF , i have this miter gear that i think could be modified, also my rig is an fx1 with a mini35 i have the original 15mm rods of the adapter but i also made 2 long aluminum rods to support a long argeniux zoom lens, maybe i could use the argeniux arri base for the FF as well , Dan let me know what you think of the gear that i have:

http://www.reggaetonmusictv.com/mitergear/miter_gear_ruler.jpg
http://www.reggaetonmusictv.com/mitergear/miter_gear_side.jpg
http://www.reggaetonmusictv.com/mitergear/miter_gear_bottom.jpg