DIY – DSLR Synchronized Zoom and Focus

Just a few weeks ago, I posted something called the HandiZoom that aimed to provide a handheld electronic zoom for DSLR lenses. The problem most people saw was that when shooting DSLR video, the lenses don't Auto Focus (at least for Canon) so as you zoom in, you'll need to chase focus. YouTube member madboardfun decided to solve that problem by taking a Nintendo Wii controller and making a DIY arduino based electric Focus & Zoom that can be programmed to synchronize the focus point. Basically it stays focused on the subject while it automatically zooms in. Very cool DIY project. [Thanks Guy]

DIY Wii DSLR Focus Zoom Synchronize Controller

25 thoughts on “DIY – DSLR Synchronized Zoom and Focus

  1. Paul Abrahams

    I just spent the weekend shooting a band and was about 20 feet from stage. I used a Sigma 70-200mm and sometimes needed to zoom in and out for different frames, the hard part was adjusting focus and doing both with one hand on the rings was hard. I'm researching what my options are right now and considering I need a hand free to hold the camera... this could be very useful!

  2. qap15

    Since i don't have Hooliwood or BBC budget, i know how hard it is to get the Hitcock or vertigo effect which is used sparingly in film but richlly in todays live events like music and other stage concerts.
    I did a DIY motorized slider and once i incopperate this solution to my slider i'll get a simple "automated" vertigo effect with just pressing a single button, which will inturn add nice motion to the static concert videos i have been doing.

  3. Guy

    @jhog, my background is in philosophy (long story), so in my view it's not possible to think too deeply about things. 🙂 I get what you're asking about now, and I don't have the answer. Basically you're asking if the relationship between zoom and focus is linear, and I'm only hoping that it is. If it isn't, then my solution won't work. the only thing I can tell you is that it works well for the lens I have.

  4. jhog

    Yeah, I meant to say 'a fixed ration per lens', i'm sure it's not a fixed ratio across the board for any lens but maybe per the particular lens that you're using. I was wondering if on some still lens zooms the ration would change up and down as you zoomed so perhaps some focal lengths in between would be out of focus. Am I making any sense? I have no idea how the optics work mechanically inside, just wondering if there might be variations or do all still zooms maintain some kind of constant ratio of focal plane to focal length. Maybe I'm thinking to deeply about this.

  5. Guy

    @jhog, I didn't suppose that the ratio would be the same for all lenses, or even for a particulr distance to the subject. Instead, you program the focus-zoom ratio on the fly using the Wii Classic buttons: zoom all the way out, dial in the focus, then press "Home" and then "-" to set the "focus at min zoom" (i.e., widest) setting. Then zoom all the way in, dial in the focus at that zoom, then press "Home" and the "+" to set the "focus at max zoom" setting. My code automatically recalc's the focus to zoom ratio every time you update either of these settings. I have a narrated video in the Instructable that demonstrates this process, along with some of the other settings. It's actually pretty fast.

  6. jhog

    @Guy, Yeah I was wondering what you'd do if you wanted to change the focal plane on the fly, it's nice to hear you've already thought about this. So if the subject suddenly moved back or forward you could easily adjust just the focus without recalibrating the zoom/focus synch? Is that relationship a fixed ratio on all lenses you think?

    Zoom is not an antiquated feature. I shoot a lot of snow sports and zooming is a pretty handy feature when your subject is either moving towards you or away from you or if you want to add drama to a shot. The problem with DSLR lenses and their huge sensors is stuff can be out of focus really easily and when trying to zoom you can never be sure where the focal plane is so I just don't zoom with em. Camcorders are nice because you can be zoomed in and in focus and as you zoom out your DOF goes to infinity plus the smaller sensor is a huge help with a deeper DOF. DSLRs are a challenge but this could be a big help without plunking down the $40,000 for one of those new ENG/DSLR Fujinons.

  7. Guy

    I'm really enjoying the discussion about my project, and appreciate all the feedback, but I should clarify a couple of things. In terms of shooting video I'm certainly not at the level of most of the readers of this blog. I mainly use my GH2 for shooting high quality videos of my daughter's dance company's performances (in addition to providing great video, the GH2 also lets me grab some very usable stills of key action points). I also use it to get some nice action clips of my former soccer players. In both of these circumstances, I do try to limit zooming within a particular shot, but there are times when I need to move from a wide shot to close in or vice versa without stopping the camera. Sometimes I get to shoot with 2 cameras, with one set for wide and the other set for close-in with which I follow the action, but even then I need to adjust my zoom quickly in order to get the framing right for the particular dance of for the action that's going on in the field. And this is the purpose for which I designed the synchronized zoom-focus feature of my controller. But if you read the Instructable that I wrote, you'll see that the controller also lets me tweak just the focus on the fly, and can be easily set up for follow focus only. In fact, you can program 6 of the Wii controller buttons with preset focus stops that move only the focus servo, so this is already a viable follow focus solution (and you can also do this on the fly, using only the Wii buttons). I made the code available through the Instructable so that others could take my solution and improve upon it, as I also plan to do. For example, I've already doubled the resolution of the servo movement, and plan to implement a wireless feature (as suggested by Mr. Cheesycam - thanks). And a big thanks to DollarBob for posting the Instructables link, and helping to maintain perspective on what my project is about. I look forward to hearing more! - Guy (madboardfun on YouTube, and grp19 on Instructables)

  8. Dollar Bob

    @MN, I agree about the overuse of zoom, but still it's a great tool in a craftman's hands. That said, I don't use it much at all because 99% of my work would not benefit from it. It's generally better just to step in (or out) with an editorial cut. Fwiw, my background is principally video, not still.

  9. Frank

    @ FabDex
    Come on - then go and buy your camcorder crap.

    Look at Proaim and Jag35 they selling much uglier and bulkier versions for 450-700 Dollars. This Guy made an DIY attempt which works better and is more silent than the Jag35 crap.

    Zooming is a no-go except for some shots and italo western.
    But you can use this setup as follow focus....maybe add an rotator controller to focus more exact. Mmmmh....think I have tp go DIY 🙂

  10. Parfocalio

    MOST PHOTOGRAPHY ZOOMS ARE PAR-FOCAL PEOPLE. I don't know why you would think otherwise. Test it out. The canon zooms for sure but like I said, most current photo zooms.

  11. MN

    Half the movies in the 70's would be less cool without zoom lens shots. Jack Lord and his hair benefitted from it, as did Shaft and Superfly. But normal citizens aren't as bad as all that, ya dig?

    Knowing when and how to pull off a good zoom is one thing, but people that don't know better abuse the heck out of it because it's a lazy way to get the shot from A to B.

    I'm from a broadcast TV background and I saw the zoom move used and abused every single day; drove me nuts.

  12. Dollar Bob

    The opening to the original Hawaii Five-O would have been completely forgettable without zooms. It's just another artistic choice. In the right hands it can be magic.

  13. MN

    Nice DIY engineering.

    Zoom moves though...gah, I hate them.

    Why would anyone WANT this feature? A zoom is so distracting. Unless your want to draw attention to the lens zooming effect for an artistic purpose I see no reason for it.

    Avoiding a live zoom is far more beneficial than creating one.

  14. Patrick

    I always thought zooming in and focusing and zooming out worked? i use canon brand lenses so this is news to be because i have never lost focus

  15. Guy

    Thanks to all for the comments, encouragement, and suggestions.

    @FabDex: I take it that your "looks like crap" comment refers to the zitters you see the zoom in the demonstration video. The zoom action is actually quite smooth, and should be even smoother when I swap my cheap servos out for better ones and change my code to use half-degree steps (it currently uses full degree steps). The bumpiness you see in the video is actually due to the fact that my lens adapter has a little play, as does my rail system. So when the focus servo, which is at the end of the lens) steps the focus along with the zoom, the lens deflects a bit. Once I build a better rail mount system (or buy one), I'll add a lens brace that will keep it from deflecting. Using half degree steps will also allow me to interleave the focus and zoom steps better. Finally, as for camcorders being better for professional jobs, I'd have to agreee that professional video work is probably not the place for something like this, but for the stuff I do (shooting my daughter's dance company performances), my GH2 along with this solution allows me to get far better results than any camcorder under $1000 can provide.

  16. jhog

    Nice. Yeah, this could be a good alternative to mega buck ENG zoom lenses. Way big opportunity IMO.

  17. FabDex

    Nice DIY project, I have to admit, but the zoom kinda looks like crap compared to a real camcorder: not something I would use in any kind of professional job.

  18. bruper

    The difference is a parfocal vs a varifocal lens. A parfocal lens will stay in focus when you zoom in / out. A varifocal lens will actually slightly adjust (correct) focus as you zoom in / out to keep everything in focus.

    - - -

    The other issue is back focus, or flange back distance. To keep focus as you zoom in/out, the distance from the back of the lens to the sensor has to be spot on.

    On ENG lenses you have a manual back focus adjustment where you can set the lens so it will keep focus.

    On Canon FD lenses, there is no back focus adjustment, so if you try to attach a FD to an EF (EOS) camera, you won't keep focus because the flange back distance is wrong (EF distance is more than FD distance, so you need an adapter with optical correction).

    BUT if you get "EVIL" mirrorless camera, like a micro 4/3 or NEX, that has a very short flange back distance, you can get an adapter to Canon FD, Nikon, etc. that corrects the back flange distance so you can keep focus while zooming.

    The trouble would be in a varifocal lens that needs camera intervention to keep focus. If you move to a camera / adapter that doesn't keep correcting the focus you're out of luck & need something like this.

    - - -

    Personally, I just feel like any varifocal lens should come with a warning label permanently attached to the lens saying it's a "fake" zoom lens.

  19. Tony

    Sounds like a manufacturing opportunity here. Performance looks pretty good in the video. We'll see what comes of this next. Proaim will take this and charge $595. lol

  20. bruper

    30 years ago, when I started with video, one of the first things I learned was that you fully zoom in first, you focus, then anywhere along your lens will be in focus, has this changed?

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