Seamless Follow Focus Gear Revolutionized by a Mechanical Engineer

by planetMitch8 Comments

Dan McComb contacted me a few days ago all excited about these seamless Follow Focus gears that he'd found that were being ‘printed' on a 3D printer and he wrote an article about it and shared it with us.

He said this in his email to me:

A mechanical engineer named Sean McCurry is making 3d-printed focus gears that blow away the competition. I think your readers will be as excited as I was to discover them:

Seems he was right, they do seem pretty awesome… read more as to why Dan loves them and you might too:

One Ring to Rule Them All: Seamless Focus Gears by Mechanical Engineer Sean McCurry

From Dan McComb:

Today I’m happy to report that such bandaids for dslr lenses are no longer necessary, thanks to a mechanical engineer named Sean McCurry, who is quietly revolutionizing the follow focus gear, one perfectly printed lens gear at a time. Wait, printed? But before we get into that…

I guess you could say that I’m a focus gear whore. I feel like I’ve tried just about everything on the market in hopes of finding one that worked seamlessly (so to speak) with my set of Zeiss/Contax primes. But every one I’ve tried has left me cold.

So. Is it too much to ask to have something as perfect as the Duclos mod, for a third of the price, that without any tools, I can install myself?

Enter a mechanical engineer named Sean McCurry. I accidentally discovered his brilliant work while surfing on Ebay a few weeks ago, when I was startled to see a listing for “Seamless follow focus gears” specifically made for Contax-Zeiss primes.

I have a lens set that ranges in size from 25mm – 135mm, and Sean had each of my focal lengths covered. For $35, I took a chance and ordered one for my 50 f/1.7 prime. It arrived three or four days later, and with great curiosity I took it out of the box.

Four pages of instructions on lens fitting were included, but were unnecessary: the gear fit PERFECTLY.

I simply had to very carefully and slowly wiggle the gear on, until it seated firmly into the spot where I wanted it to stay on the focus barrel of the lens. The fit is so tight that it doesn’t slip at all, doesn’t require glue, and feels like it was made for my lens. Which, in fact, it was.

I’m not 100 percent sure how Sean is able to make such killer gears. But I’m confident it’s because he’s 3D printing them. A close examination of the gears reveals telltale patterns, strata in the plastic that are consistent with 3d printing.

Seamless Focus Gears by Mechanical Engineer Sean McCurry

Seamless Focus Gears by Mechanical Engineer Sean McCurry

One great thing about these gears is that I was able to place them at approximately the same position on 4 of my 5 lenses, so that when swapping lenses, I don’t have to adjust the focus puller position on the rails. Also, my previous gears would ride up and down the lens as they came in and out of their foam Pelican case, requiring constant readjustment, often in the middle of a shoot. These gears stay put.

Full list of supported lenses are available HERE

Read full article on Dan McComb's post: One Ring to Rule Them All: Seamless Focus Gears by Mechanical Engineer Sean McCurry

  Note: it is our policy to give credit as well as deserved traffic to our news sources – so we don't repost the entire article – sorry, I know you want the juicy bits, but I feel it is only fair that their site get the traffic and besides, you just might make a new friend and find an advertiser that has something you've never seen before  

(cover photo credit: snap from Dan McComb's post)


  1. Curious.. can you “glue” them in place to keep them there on the lens? If they are made specifically for one lens, why take them off? My concern would be if they’ll stretch at all during use and get loose. For $35 that’s pretty steep for one gear but if it’s a tight fit and never stretches that would be decent. You could probably pick up a printer for a few hundred and print your own too. 🙂

    1. You don’t actually need to glue them – they are a perfect fit for each specific lens. And yes, they are designed to be left in place semi-permanently, not taken on and off. That’s exactly what I’m looking for in a focus gear – something I can leave on my lenses and never have to fuss with.

      Re: stretching, they are printed from Delrin, a plastic resin that, according to maker DuPont “combines lubricity and wear resistance with the stiffness and strength needed in parts designed to replace metal.”

      These gears are in effect a way to do the Duclos mod (which runs more than $100 per lens) at home, by yourself, without the loss of your lens while you ship to Duclos for the mod, for a third of the price. Pretty sweet.

      1. Hi Dan,

        Great stuff! Been through a lot of different gears for my Contax set. This is a product I’ve been wanting for ages. What would the turn around time be for on a set for:

        21 – 2.8,
        28 – 2.8,
        35 – 1.4,
        50 – 1.4,
        60 – macro 2.8,
        85 – 1.4,
        100 – 2,
        180 – 2.8
        Tokina 11-16 2.8

        Best Wishes

  2. This is why I love 3D printers so much. They can literally make just about anything and this is only proving that. I am really excited by this and I will be looking forward to getting my own very soon. 🙂

    1. It’s so cool right? There’s so many cool things one can do with a 3d printer at their feet. I have a good friend who has a really cheap 3d printer, and she has been able to create some fun 3d models and toys out of it. I might tell her to try making something useful for cameras.

  3. I am really interested in these, as well as other interesting 3d printed camera parts in the future. We should be able to print off expensive parts for cameras. Kind of makes me want to buy my own 3D printer and come up with cool attachments.

  4. Looking very attractive – nice job, Dan

    Any chance you’ll make a Leica R series in the future?


  5. I discovered Sean’s printed lens gears months ago when he had gears for only a few lenses
    and they are everything he says they are.
    I have them on most all my lenses, they work perfect.
    And they are completely guaranteed if someone is not satisfied.
    Everyone is.

Leave a Comment