Focus GEAR RING production HELP NEEDED

[Cristian Mihai]

Hello guys! Since i am very new into videography please help a rookie! I have started to get ZEISS lenses both new ZF.2 but also a lot of CONTAX ZEISS. Having now 10 lenses ( and getting bigger by the week ) i came to the conclusion that cinemoding my lenses as many of you will be a too big expense for me. SO:I am working on a prototype of gear focus as you can see below. I decided to make my own because :- my choice of material ( i choose aluminium cause is more durable, more stable in the milling machine and i can make a proper locking mechanism in 3 point so the lens is centred with the ring- price ( i intend to make more of these and sell also to cover the drilling, milling and maybe anodising costs )- easy to install with 3 very small allen bolts that put pressure on 3 small plates between the lens and focus gear ring- custom ( i will produce the inner diameter for each and every lens in 1-2 days I need HELP and if some of you can answer these questions would be great :- what materials would you prefer and why - what OUTER DIAMETERS ( i suppose there will be 2-3 standards but i don't know them so please tell me your opinion ) how many tooth's - how much would you pay for one of these and why not more ( i need these to negotiate with the local milling shop )- would you like it anodised and what colour ( these will add to the price )

 

[Steve Gal]

This has been done with aluminum gears and set screws in 3 points. Problem is, all 3 are never tightened the same amount and puts pressure on the focus ring making focus tight eventually causing damage to the lens. Also not to mention the marks the metal does to the lens cosmetics. I myself stay away from this type of gearing. Solid delrin cut and fit to a lens yields even pressure around the focus ring and will not damage at all. Here is a picture of my gear upgrade.

http://www.duallcamera.com/dev/comp...ge/product/Leica_80mm_f_1.4_50f852ae7d312.jpg

 

[Nick Gardner]

Having made a bunch of lens gears, I agree with Steve, Delrin is better. However, if you are sold on aluminum, a clamping action is better than set screws. The gear gets slit and a hole is drilled and tapped so a single small machine screw pulls the diameter of the gear tighter.

Nick

 

[Clayton Burkhart]

Jerry at JBK already makes the type of ring you are describing.

http://www.jbkcinequipt.com/


The advantage of course is that you don't have to send in your lens to have the rings made.

 

[Cristian Mihai]

Thanks guys for input! The screws i intent to use will not apply pressure directly on the lens ! I am looking at placing something in between but i will give it a try also with a delrin. Problem with delrin around my area is hard to get and most certainly it runs under a different name in here so will have to look into that ! Learned in a month here more i was expecting !