Thread: Pulling repeatable focus using the internal motors of an electronic lens...

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  1. #1 Pulling repeatable focus using the internal motors of an electronic lens... 
    Senior Member Dave Draper's Avatar
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    If pulling focus on an electronic lens -- utilising the internal motors of that lens -- is using Fool Control, better, worse, or the same as pulling focus using a wired controller (such as a Teradek Thumbwheel or Smart Knob) without an external motor?

    Secondly; is it possible to pull *repeatable* focus on an electronic lens, if using a controller -- whether wired or via WiFi -- that utilises that lens' internal motors?

    Thirdly; would a better choice be to use an external motor? Or are electronic lenses "focus by wire" even when in "manual" mode, and therefore incapable of repeatable focus pulls?

    Specifically referring to Sigma Art Primes here.
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  2. #2  
    From my experience, pulling focus on the phone... Not really doable. You could use the phone to set focus but not really following someone walking around or such. Also the wifi is quite flinchy so better have the phone wired to make fool control work.

    Optitec and the others work well, I would say much better than external motors that push pull the lens around too much and will wear it out.

    you get good repeatable focus and quick calibration. The normal problem is the resolution of the internal motors... not always smooth pulls but slightly studdering, more on some lenses less on others. Also more stuttering when adding weight to the lens like screw on filters mattbox etc.

    I find it a good option for run and gun kind of work, especially hand held where you dont ever see the stuttering focus as the camera is floating. But with a fixed camera doing focus racketing or such still lenses is simply not a good option / still not on par with quality built cinema housings and focus motors.
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  3. #3  
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    Sigma EF primes and pulling focus with internal motors using the teradek RT/lattitude is repeatable and pretty damn amazing. I shot a whole spot for mercedes like this. You need to definitely test, but it can be a great solution in a lot of situations.
    JAKE WILGANOWSKI
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  4. #4  
    Senior Member scott pommier's Avatar
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    I have the RT motion "Latitude" side module (the DSMC 2 specific unit.) I haven't tried the Sigma Art Primes, but here's my experience with Canon "L-series" EF zooms/primes and the Sigma 18-35 zoom: The Canon lenses work pretty well, all things considered. In a more controlled setting, with marks, you would be much better off using external motors. But using the RT motion thumbwheel I've been been happy with what I've been able to do on my own. The Canon lenses are pretty smooth, with some you'll find a noticeable step. So if you're subject is walking towards the camera, on a longer take you may have a section where no matter how smoothly you adjust the focus, it will still have a slight jump. Unacceptable in some circumstances, manageable in many others. The Sigma 18-35 doesn't seem to work with this configuration at present. For how light and fast it is to work with EF lenses, I'm amazed at how well it works. I think the Canon L glass looks great (although not a very matched set) so I get a lot of use out that setup, but if you need precision, repeatability, you'll want cine lenses and external motors. The RT motion motors are great but there are a number of options once you go that route.
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  5. #5  
    Senior Member Jacek Zakowicz's Avatar
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    I can only speak for our product- OptiTron2. The focus pulling, especially on Sigma Art Series, is smooth as butter and 100% repeatable. We have a removable marking rings on it that once marked can be used not only for a particular lens but all copies of the same lens. Sometimes the new release software initially may cause some issues but, once bugs get ironed out on the RED side, its is smooth and repeatable pretty much throughout the last 4 years of the RED compatibility we provide. It is also a RED Approved Product....
    Jacek Zakowicz, Optitek-dot-org, jacek2@optitek.org
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  6. #6  
    Senior Member Mark Andersen's Avatar
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    Quote Originally Posted by Jake Wilganowski View Post
    Sigma EF primes and pulling focus with internal motors using the teradek RT/lattitude is repeatable and pretty damn amazing. I shot a whole spot for mercedes like this. You need to definitely test, but it can be a great solution in a lot of situations.
    I agree here. Sigma ART still lenses are much smoother than the Canon’s I have used. Really don’t see any stutter with Sigma. Where I really love using Sigma Primes and Latitude is on the gimble and in very run n’ gun handheld situations. I usually only work this way went the focus puller is focusing by eye on a big monitor. If you are going with repeatable marks and lens markings etc. then it’s not so slick.
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  7. #7  
    Senior Member Nils Ruinet's Avatar
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    Been using the RT Motion Latitude with Sigma ART lenses (18-35, 50 and 85mm) since it came out and it works very well. It makes these photo lenses actually usable in a professional and demanding environnement. Perfect setup for lightweight setups like on gimbals. And when you want to use PL lenses, you can just add a motor and use it the traditional way. Best of both worlds.

    The Canon 70-200 works correctly too, the Tokina 11-16 not so well (marks change after some focus pulls, not good). So you need to test with the lenses you wanna use.
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  8. #8  
    Senior Member Bérenger Brillante's Avatar
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    I'm using the Latitude since it came out too, and before that Foolcontrol, both with Sigma Art lenses, and it's really nice, but it's not perfect. But almost.

    You can actually see some stutter with these internal motor if you do macro works. It's the only situation where I was able to notice it was internal motors. And even then, it's really usable with Foolcontrol's auto focusing marks, and thus it is repeatable. It was actually the only solution for the macro work to be really smooth.

    So yes to internal motors, I just wish the Sigma Art PL had kept them in.
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