Forgot your password?

Comment: Re: only manual lenses? (Score 1) 45

by dgatwood (#47956915) Attached to: Video Released, Crowdfunding Underway For Axiom Open Source Cinema Camera

...the connection between the manual focusing ring and the lens part is electronic rather than mechanical...

Just because a lens has electronic focus doesn't mean that it doesn't have mechanical manual focus. At least on the Canon side of things, focus-by-wire lenses are rare. Most of the focus-by-wire lenses are old, discontinued models like the 50mm f/1.0. The only current focus-by-wire lenses I'm aware of are their STM lenses (mostly low end) and the 85mm f/1.2L II. The rest of their L line is mechanical, including the 50mm f/1.2 L (popular for movie work), the 135 L II, their various zooms, etc.

The big advantage that fully manual lenses have over autofocus lenses when it comes to manual focusing is that most manual lenses have a longer throw. This makes it easier to get a more precise focus when focusing manually. They don't do that on autofocus lenses because it would make focusing slower.

With that said, I think the industry's obsession with manual focus is badly misplaced. When you're dealing with 4K video, you want the focus to be right, not just close, and autofocus is a lot more precise than any human can possibly be, even with static subjects, with the best long-throw lenses, and with a separate person doing nothing but handling the focusing. The only thing holding back autofocus for video use was the slowness of contrast-based autofocus (and its tendency to seek). With the advent of on-die phase-detect autofocus capabilities, that limitation is rapidly disappearing. Add a bit of eye tracking into the mix, and I think you'll find that within the next ten years, nobody in their right minds will still be focusing manually, particularly when they're shooting 4K.

it is often better if the aperture can be set in a step-less fashion

AFAIK, that's fairly rare even in fully mechanical lenses unless they've been modified. Perhaps dedicated cinema lenses are different in that regard. I'm not sure. But even some of my old screw-mount lenses from back in the black-and-white TV days had mechanical stops, so I'm guessing stopless lenses aren't exactly common.

So I can conclude that while having a powered mount is very much desirable on Axiom cameras (and so it will come just a bit later) it is also true that the old lenses are in fact more suitable to the task of shooting movies and so the decision to deliver a fully manual Nikon-F mount first is justified

The problem with old lenses is that they're designed for a world where cameras had relatively poor spatial resolution, and for much less reflective sensor material (film). I enjoy playing with old lenses on a 6D, and they create an interesting artistic feel, but they don't even approach the level of flare resistance, sharpness, etc. that you'd want for a digital 4K cinema camera. So if you're limiting yourself to mostly old lenses, you might as well limit yourself to 720p as well, because you'll be lucky to out-resolve that with most lenses designed more than about a decade or so back.

And if you have the money for modern, full-manual cinema lenses, chances are you aren't in the market for anything less than a highly polished, turnkey camera system.

So I really think that they need to at least lay the groundwork (in hardware) by making the plastic plates in front of the sensor removable and by including USB and DC connectors near the back side of that plate so that the system will be readily extensible in the future. That small change shouldn't require a huge amount of effort, and it will future-proof the design in a way that nothing else will.

Or, if USB isn't feasible, a high-speed serial port capable of at least 230 kbps would probably be good enough.

Just my $0.02.

Comment: Re:"compared to consumer grade cameras" (Score 1) 45

by dgatwood (#47956721) Attached to: Video Released, Crowdfunding Underway For Axiom Open Source Cinema Camera

I think you missed my point. If they don't provide an electrical interface near the front of the hardware as part of the core design, there's no way that users can develop any electronic mount hardware, because there's no way to communicate with said mount hardware... or at least none that doesn't involve a box fastened to the back of the camera with a wire wrapped all the way around the camera to the front.

That said, so long as they provide a multipin connector with full-voltage DC and USB pins on the interior of the body, just inside the mount, that's good enough to make it possible to add electronic mount hardware by replacing the mount with a redesigned mount. That's the minimum that the core developers must do. If they don't, first-generation hardware users will be stuck with that limitation forever, and folks will try to work around the lack of that hardware with disgusting workarounds, which future hardware users will then get stuck with... probably forever. :-)

Comment: Re:"compared to consumer grade cameras" (Score 2) 45

by dgatwood (#47955691) Attached to: Video Released, Crowdfunding Underway For Axiom Open Source Cinema Camera

The biggest problem I see with this is that the lens mount system appears to be purely manual. This seriously limits the lenses you can use, because these days, 99% of lenses don't have mechanical aperture control. They really need to have some sort of adaptable lens electronics in this thing, so that people can design adapters that actually support modern lenses, similar to the Metabones adapters for NEX. The absolute minimum requirement for such things is a set of electronic contacts inside the lens mount that are controllable through software.

I think if I were designing a camera system to be extensible, I'd make the lens contacts speak USB 2.0, with appropriate short-circuit protection for when the lens is being attached to the mount. That way, the adapters could be very basic USB controllers that speak a particular lens protocol, rather than having to convert one arbitrary lens protocol to another (potentially incompatible) protocol.

There is one caveat to using USB, though. You'd need to also provide a 7.2VDC pin on the lens mount. Many camera lens systems require that much voltage to drive the focus motors, and it would suck to have to boost the voltage from a 5VDC USB supply in an adapter, particularly given that you probably already have the higher-voltage DC supply floating around inside the camera.

Comment: Re:I FIND THIS HIGHLY... (Score 1) 440

by Jeremiah Cornelius (#47949003) Attached to: Science Has a Sexual Assault Problem

It's a little [illogical] to say a tomato is a vegetable. It's very [illogical] to say it's a suspension bridge.

Logic is a binary function. Something is in a logical set - or it is not. Being illogical is not a synonym for being mistaken. Degrees of precision are irrelevant for set inclusion. Fuzzy logic is not logic.

BTW: It is illogical to conclude that a Tomato in NOT a vegetable, simply because it belongs to a taxonomical subclass, "fruit". It as if I were to say your testicle is not animal.

Comment: Re:Edge routers are expensive (Score 1) 85

by dgatwood (#47948583) Attached to: Why Is It Taking So Long To Secure Internet Routing?

First, I'm not talking about adding any additional gear. There's no reason that what I'm talking about can't be handled entirely in the DSLAM or head end or whatever and in the existing CPE hardware that talks to it.

Second, I wasn't really talking about changing the CPE for business customers with fiber connections anyway. They're not (usually) the ones who are constantly on the phone with tech support saying "The Internet is down" when really, they just accidentally unplugged something. I'm talking about providing smarter, preconfigured cable modems and DSL modems for home use.

Numeric stability is probably not all that important when you're guessing.