building a Follow focus

[wadoman]

Ok so my buddy (another dvxuser member)wants me to make him a follow focus(among other things) for his Panasonic HVX 200. Now first off I don't know much about cameras and camera equipment. So I am here trying to get some idea on what are the "required" features for a follow focus and make sure Im doing all the right things. I have done some research and I understand basically how they function and I already know roughly how it will be constructed, but there are some technical specs that I need mainly with the gears. I am planning on making it as professional as I can and I'll be machining everything myself (CNC) even the gears if I cant find what I need.

This is the type of FF I am going for:
http://www.redrockmicro.com/mff_product.htm

It will be machined aluminum with plastic gears. I will be making my own 90 degree gear box uisng miter gears. It will be a double 15mm rod mount. It will have an adjustable slide-mounting mechanism. The lens gears will be the clamp style. The hardest part of course is the gears. So for the gears is a 1:1 ratio a standard for FF? Is there a standard diameter for the lens gear?

So if anyone has anything they would like to add or recommend about the gears or anything else then please do.

Thanks in advance

Dale

[Lighthouse]

Unless you are using Primes, or supplemental lenses on a Red Rock, Letus or similar unit, you don't really need a follow focus. I've done really well using the electronic focus devices offered by BeBob Foxi and Varizoom. I love the Foxi. It is very accurate and has good resistance, similar to a follow focus on a prime lens. It also handles iris control, which is all nice when you don't want to be fiddling with the lens and iris on a sensitive shoot. You get much smoother action from the electronic devices. In fact, I use a varizoom on my Artemis and I'm able to operate the record stop/start, zoom, focus and iris all with my right hand while my left hand steadis the rig. I'm able to do some pretty accurate focusing using the measuring scale in the display (an external monitor) and can manage the rig without assistance. I'd think long and hard before I switched to a follow-focus for the on-board Leica lens.

Hope this helps.

[wadoman]

I did some more research on those suggestions. I understand what your saying and the electronic focus is a real nice unit. He does use supplemental lenses though.....I believe. I know he has an adapter that he uses to attach other lenses. I assume this is what you are talking about. I have yet to fully examine his gear in detail and take measurements. Again I apologize I don't know much about camera equipment. Its for my buddies camera. I'm hoping he will pop in and put in some input on his camera setup.

[mmastunts]

hey wado it's Matos. yeah on my hvx 200 i use a brevis adapter with the flip kit. The follow focus would be used for the lenses I would attach to it. electronic focus would be cool but i don't know much about those mechanics

[wadoman]

Hey thanks for dropping in Matos. So here is a quick and rough picture of the basic ROUGH dimensions I am using:

http://www.steelcannonprods.com/imageUploads/FF/FollowFocusRef.jpg

I still need to get the measurement between both rods which I can get from his camera rig and I also need to get the diameter of the focus on his lenses but now I need to know if there is a standard outside diameter of the lens gear/s? I dont think it is critical, but I would like to stick to what the standard is, just to keep as universal as possible.

Any comments welcome.

[mmeiring]

As stated on this page (http://shopping.netsuite.com/s.nl/c.472981/it.A/id.405/.f). The rods are on 60mm centers. Look forward to seeing your results. I've been thinking about taking this one on myself.



Hey thanks for dropping in Matos. So here is a quick and rough picture of the basic ROUGH dimensions I am using:



I still need to get the measurement between both rods which I can get from his camera rig and I also need to get the diameter of the focus on his lenses but now I need to know if there is a standard outside diameter of the lens gear/s? I dont think it is critical, but I would like to stick to what the standard is, just to keep as universal as possible.

Any comments welcome.

[wadoman]

@mmeiring Thanks for the Page. I did see that, but I just need to measure his rig to make sure it's the same. Once I get the needed specs I will build it in CAD before I cut anything.

[Dreamish]

You should really use metal gear for the gearbox. Plastic gear=flex. And the biggest challenge=eliminating gear play.(That's the main difference between a cheap and expensive follow focus.)

Another thing is that you have to make the structure of the follow focus itself as rigid as possible. Especially the parts connecting the drive gear and the rod support clamping thing. Because when you pull focus that part will be the "stress point". If the structure is not solid enough the whole unit will flex. Even 0.1 degree of flex=flex. More flex=more play. So redrock's unit is a bad design look at how thin is that metal thing connecting the drive gear to the rod support.

[wadoman]

@Dreamish- Thanks for the advice. I will definitely go a different route then redrocks unit. I'm going to experiment with different miter gears for the gear box as well.

And Thanks to another member that PMed me with loads of helpful information.

[wadoman]

Did a little research on gear options and other rigs and I think I will go with metal helical gears.