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> ELP makes many modules like this, and they're <$100 and work well. Slight off topic but do you have any recommendations on cameras with motorized focus that

> ELP makes many modules like this, and they're <$100 and work well. Slight off topic but do you have any recommendations on cameras with motorized focus that can be controlled electronically? For example with OpenCV's CV_CAP_PROP_FOCUS flag?

blagie 4y ago
I have no recommendations there matching 100%, but one of these might work: Many (perhaps most) off-the-shelf webcams do allow you to control focus, but aren't C-mount, and you're stuck with their lens and their preprocessing. For what I do, webcam preprocessing makes it almost useless for my applications. Almost all are auto-something, and I don't need exposure or white balance changing once I've calibrated lighting and a machine vision pipeline. Many do nominally have manual exposure and white balance controls, but I've had poor luck finding ones where I have consistency at the level of a module like an ELP. If you're willing to hack or forgo OpenCV integration, it's ridiculously easy to control C-mount lenses with electronic focus control. That's what I did when I needed to do this. You can look on eBay for something like a vintage Computar TV Zoom Lens (and documentation on Computar's web site still existed when I did this). Prices vary, but when contractors rip out ancient surveillance systems, these can be had for a song. Or you can splurge, and get a 20x zoom f/1.8. The ones I bought, it's literally just applying a voltage to a pair of wires to make it zoom or focus in one direction or the other. You just need a few GPIO pins, and to step up the voltage to what it needs (I'm inclined to say 12V, but it might be 5V; it's been a while -- but from not recalling, you can see how easy this was; if this was a week project, I'd remember). What you really want is a module with the same interface as something like the Computar, which I know exist, but I've never used, so I can't recommend them one way or the other. And it'd be easy to hack into OpenCV if you really wanted.
- DoingIsLearning 4y ago
  Thanks for the pointers indeed controlling the focus motorized control might be easier and more guaranteed result than a software/driver only solution, I wasn't really considering that before. Thanks again!

blagie 4y ago

I have no recommendations there matching 100%, but one of these might work: Many (perhaps most) off-the-shelf webcams do allow you to control focus, but aren't C-mount, and you're stuck with their lens and their preprocessing. For what I do, webcam preprocessing makes it almost useless for my applications. Almost all are auto-something, and I don't need exposure or white balance changing once I've calibrated lighting and a machine vision pipeline. Many do nominally have manual exposure and white balance controls, but I've had poor luck finding ones where I have consistency at the level of a module like an ELP. If you're willing to hack or forgo OpenCV integration, it's ridiculously easy to control C-mount lenses with electronic focus control. That's what I did when I needed to do this. You can look on eBay for something like a vintage Computar TV Zoom Lens (and documentation on Computar's web site still existed when I did this). Prices vary, but when contractors rip out ancient surveillance systems, these can be had for a song. Or you can splurge, and get a 20x zoom f/1.8. The ones I bought, it's literally just applying a voltage to a pair of wires to make it zoom or focus in one direction or the other. You just need a few GPIO pins, and to step up the voltage to what it needs (I'm inclined to say 12V, but it might be 5V; it's been a while -- but from not recalling, you can see how easy this was; if this was a week project, I'd remember). What you really want is a module with the same interface as something like the Computar, which I know exist, but I've never used, so I can't recommend them one way or the other. And it'd be easy to hack into OpenCV if you really wanted.

DoingIsLearning 4y ago
Thanks for the pointers indeed controlling the focus motorized control might be easier and more guaranteed result than a software/driver only solution, I wasn't really considering that before. Thanks again!