The intracies of modern camera lens repair (2024)
salvagedcircuitry.com
salvagedcircuitry.com
Even a fast fuse is very, very slow compared to semiconductors. I've seen transistors blow up to "protect" fuses. They're for stopping fires and preventing the slaughtering of batteries, nothing more, nothing less.
Induction motors use overload relays to protect the motor, fuses are strictly for overcurrent protection to stop the wire from catching fire. A VFD will have a fused switch or circuit breaker on the line side for overcurrent protection and a set of overload relays after the contactor to protect the motor itself.
Switchgear uses ground fault protection relays to protect the equipment, not fuses (or humans for that matter, GFP relays are set around 30mA IIRC)
Some motors also have phase loss protection relays that will power down the motor if a utility phase is lost.
A car is the same, fuses are to protect the wiring and prevent fires. Fuses do not act quickly enough to protect equipment, even fast-acting ones.
Relays act fast enough and deterministically enough to protect equipment, fuses aren’t fast or accurate enough to do so.
In well-designed microelectronics, they will.
The standard circuit involves a fuse, a fast Zener clamp, and sometimes a small resistor (e.g. 1 ohm) and/or capacitor. The design parameter is that, with the current limit from the resistor, the Zener should not blow out before the fuse.
The resistor needs to be small enough to not lose a lot of voltage under normal operations, but to still protect the Zener during the short surge during which the fuse blows. For most microelectronics, that's not hard. A 0.5W USB device might have 100mA of current max, which across 1 ohm is 100mV, so negligible for most purposes.
With high-power devices, it gets more complex.
Of course, consumer devices (a) will never be fixed (b) don't sell on this (c) every penny counts, so there's no market pressure to do things right.
But that's how we used to do it, and how it's still done many places where things count. If I'm building a one-off or few-off, it definitely will have proper protection.
Really, if you care beyond "blow the fuse if something shorts", you need active current limiting. For common cases like USB ports, you can buy chips that do it cheaply and efficiently. There are also some textbook circuits, though they each have their pros and cons. No matter what, if you've got a pass transistor or switching transistor that's about to go seriously overcurrent, you have to do something about it with active parts -- fuses aren't going to get it done.
But defense in depth is always a good strategy, and fuses play a key role there. The active circuitry saves the rest of the design; if it can't get the job done, the fuse makes sure nothing burns.
Orrr you can design your circuit to survive a short condition for a bit longer than a fuse takes to blow. For old cars this was common, let whatever is short take all the current it wants for a tenth of a second and forget about it.the battery may lose a bit of useful life but those things were gonna fail early either way.
Tamron lenses for instance will allow a wired control or a wireless dongle to communicate with an app/computer and change the lens behavior, switch what the physical buttons and rings do. Potentially you can manage stepping through settings for stop motion like effects, time lapses or stacking.
We're far from the days a lens was just metal and glass※. There are obvious downsides, but in practice it's actually a huge stepup IMHO. Every photographer is different and does different things, being able to fully adjust your gear is a godsend, especially as we need speed and reactivity.
※ there are still plenty, and plenty more will be designed and produced anew, but I don't think it's the major trend.
Besides the slightly interesting stuff Tamron is doing, why on earth would I want firmware updates for a lens? Also, this seems like it would be much more readily accomplished by the camera itself… if you’re doing weird stop motion racking and whatnot, why would you rely on the camera and lens being separate? Seems like kind of a pain to me.
You could argue that the camera should do firmware updates but the manufacturers for (semi) open mounts like the ones Tamron is making lenses for don't want to have to design a protocol to do updates for third party lenses through the body when the lens manufacturer can just slap a USB port on the lens and call it a day.
The port is also useful for customizing the lens functions. For third party lenses the camera can't be expected to manage those functions.
No, no you shouldn’t. There’s no reason why a microcontroller should ever need its firmware updated. The only reason why you would need to update the firmware is to add features, which I guess is mildly interesting for the tamron, but like I said… you could handle all extra fancy focusing things in the camera body itself. Just give me a dumb lens that does exactly what the body tells it to do.
It's hard to convey, but for instance you can reverse the fo us ring rotation, which probably only resonates with people who had to deal with it daily.
Or you can adjust the ring travel.
Or make the focus ring work as an aperture ring instead. Or straight disable annoying buttons.
Up until now you'd have to go hunt the perfect lens where the maker was 100% on board with your preferences. Or adjust your whole shooting style to every gear you use.
Sure a camera body could handle every single settings of third party lenses. But given what we've seen these 2 last decades, I don't think there was any chance of that happening. Tamron is partly Sony owned and they still did it on their own.
I'm not aware of what exactly is changing, but I've already seen it happen with newer Sony bodies getting released, and an update going to Viltrox lenses to fully support thems.
On the camera and lens being separate...in an ideal world you could ask the camera to do absolutely everything. In practice that's a tough order for a single company.
The bright side is also that you can use a mildly older body while benefiting from a very flexible lens, or have different profiles for different lenses and not have the body care about which lens needs what.
I can't imagine Nikon be bothered to properly operate a software ecosystem TBH.
One reason is to update the lens to work with new camera or new camera firmware.
Improved algorithms for focus hunting, diminishing chromatic aberration (most of it is in the glass but some positioning can tweak it).
I get it, there's not a lot that will happen there, but some of that stuff will be useful on an investment that can easily be several thousand (I don't get into the wildlife telephotos, but two of my lenses were $3,300 or so - RF 85/1.2 and RF 28-70/2).
Iam not sure if this is a general truth. I recently bought a canon rf 24-70 f/2.8 which is pretty SOTA and it does not have an USBC port.
Sigma has a dock that allows updates to their lenses in this fashion however.
Would have been nice if Sony just let you drop a file on the sd card to load an update.
I only have one lens tight now (I tend to stay small on my system but this is a low point) but I'll keep it in mind.
Thanks for the info!
For some reason, cinema lenses are still - for the most part - purely mechanical. For film and TV, most camera operators still focus manually - often via gears attached externally to the lens.
Coming from modern photography, manual focusing is inconvenient and difficult to learn. But there's something very old-school cool about cine lenses. They feel great.
Its probably a scale thing. Photography lenses make up for the design, engineering and manufacturing costs with scale. Everyone who takes photos needs lenses. But far fewer films are made, and cine lenses are often rented. So they really can't be manufacturing that many units in total. I suspect they don't manufacture cine lenses in high enough volume to justify the engineering costs of fitting complex microcontrollers and motors into the lens housing. And if the production can afford to hire a focus puller anyway, autofocus just isn't that valuable.
Autofocus in moving pictures isn't so great. It might be nice when you're not filming, but while filming, a focus change should really be intentional; auto focus isn't that. Might depend on what you're filming though.
As a solo operator, autofocus is great. Maybe the right metric is the number of crew per camera. 2-3 crew per camera? Manual focus is fine. 2-3 cameras per crew member, like solo filming a podcast or a theatre show? I'd choose autofocus every time.
For motion picture cinematography, I've seen remote controlled focus anyway. I don't see why you could not have a good motor built I to the lens and remote control it. If the external motor focus is quick and precise enough, then the internal motors should be as well.
Ideally, camera bodies should support firmware updates via the body in a non-discriminatory way, but until then I wish manufacturers support firmware updates via USB-C.
Looking at you Samyang Lens Station. I think users have been sufficiently upset, and they're adding USB-C to newer lenses.
Mirrorless has restored the utility of manual focus lenses in such a dramatic way that many of the significant advances in optical quality at every price point are happening in manual focus, and there is a real return to the understanding of the value of lens "character".
Time will tell how much of this is a stepping-stone to Chinese manufacturers moving to AF lenses (which is definitely a part of it) but many of the best new lens designs are coming from the likes of Cosina-Voigtländer and various cinema-adjacent stills brands.
So do you mean that even camera lenses now ship unfinished?
Roughly in the layout of the way they came out. Top to bottom, in layers, as it comes apart.
A habit from working on laptops in a warranty center. I might have to try some tape.
I’ve also seen a clever technique of drawing a diagram of whatever you’re working on on cardboard, and stabbing the screw into the cardboard to keep track of where everything lives
This is incredible work, though.
But if you happen upon a real PH-0 it will destroy the JIS screws.
That way someone can specialise in just fixing Xboxes for example and make a nice profit.
Getting robots to do this would be incredibly difficult because it’s too custom and too fiddly. They don’t even use robots for most of the work originally manufacturing these lenses.
If you mean the submitter, they only get a short interval of time to make such changes ... shorter than the six hours it has been up already.