That was a fun site to browse. I really enjoy fixing / hacking on non-disposable equipment (lab, test, optics, etc.) and there are some well-done write-ups in there.
Thanks for stopping by! :D
The intracies of modern camera lens repair (2024)
71–80 of 88 posts
Re: The intracies of modern camera lens repair (2024)
#72Glad I only fix old manual lenses. The Nikon AI/AI-S era ones are less scary :)
The Nikon AI/AI-S era lenses are fun to repair, but this sigma was not too bad. I've repaired some very intricate panasonic / olympus consumer lenses that were far more complex.
Re: The intracies of modern camera lens repair (2024)
#73Earlier quoted context omitted.
That's a good design for input overvoltage protection (assuming I've drawn the correct schematic in my head). But it doesn't help against most other fault conditions, particularly anything to do with the load/downstream going short. 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. Th…
Yeah, fuses are more of a overload protection kind of stuff. For cases where the load is trying to kill itself and you with it you need current limitation circuits, either on a converter or a latch current limiter. 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…
Just want to mention how much I appreciate this discussion and the opportunity to learn from it. This is what I come to HN for (nowadays there are also really interesting YouTubers who do informative teardowns of power electronics and other devices, too e.g. Labo de Michel, Watch Wes Work, etc.)
Re: The intracies of modern camera lens repair (2024)
#74The TPS62140's 30ns propagation delay is not enough to blow a fuse. The first rule of fuses (which many modern engineers do not understand!), is that fuses are not there to save your parts, and they simply will not do that. Fuses exist to prevent fires. 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 slaug…
It's a scale problem; fuses can be set up protect components or machines in a car or factory context; and often this is what is taught (or what people have first hand familiarity with). It just doesn't scale down to semiconductor level.
Even in a car, fuses are there for safety. A car battery will easily start a fire if there's a short anywhere in the wiring or accessory devices.
Re: The intracies of modern camera lens repair (2024)
#75The TPS62140's 30ns propagation delay is not enough to blow a fuse. The first rule of fuses (which many modern engineers do not understand!), is that fuses are not there to save your parts, and they simply will not do that. Fuses exist to prevent fires. 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 slaug…
It's a scale problem; fuses can be set up protect components or machines in a car or factory context; and often this is what is taught (or what people have first hand familiarity with). It just doesn't scale down to semiconductor level.
> It's a scale problem; fuses can be set up protect components or machines in a car or factory context;
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.
Re: The intracies of modern camera lens repair (2024)
#76Earlier quoted context omitted.
Because third party lenses cannot leverage the camera body to update. Sigma has a dock that allows updates to their lenses in this fashion however.
I suppose it depends on the system? I have updated Sigma, TAMRON, and XiaoYi lenses on my Panasonic and Olympus MFT bodies, as well as Panasonic and Olympus with each other: https://support.jp.omsystem.com/en/support/imsg/digicamera/d... (Sadly not an exhaustive list. I have firmware for several more lenses stashed away in my archive, but the upgrade mechanism is the same.)
I shoot the m43 system (have since the GH2, then E-M5, E-M1, and now a G9 II) and didn't realize this.
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!
Re: The intracies of modern camera lens repair (2024)
#77Earlier quoted context omitted.
Because third party lenses cannot leverage the camera body to update. Sigma has a dock that allows updates to their lenses in this fashion however.
You can update sigma lenses through Sony camera bodies but it requires running a program on your desktop with the camera plugged in and it’s a bit of a pain. Especially on macOS where it requires enabling kernel extensions. Would have been nice if Sony just let you drop a file on the sd card to load an update.
Didn't realize this, thanks!
Re: The intracies of modern camera lens repair (2024)
#78Earlier quoted context omitted.
> For those who haven't followed the camera world for a while, at this point a lens for a mirrorless camera will have a USB-C port to receive firmware updates. 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.
Third party lenses that cannot be updated by the camera body will include a USB port.
Ok, that makes actually sense.
Re: The intracies of modern camera lens repair (2024)
#79How did the intricacies become "intracies"? ;-) That's the question.
Re: The intracies of modern camera lens repair (2024)
#80Earlier quoted context omitted.
You also have the sonar/radar thing on the camera which can measure distance. Can that be hooked into focus so it's automatic?
If you’re going to go through all that trouble you may as well just use a lens or cam body with a quality, built in AF. Way cheaper and the tech has matured greatly. Plus even with lower to midgrade cameras it’s easy to find a capable system with a solid codec you can color match enough with the rest of the movie. Even my GH6 I travel with can shoot 5.7k pro res
I was talking about movie-grade setups, I was wondering why they need the sonar thing if they focus manually anyway. Maybe it's useful for post-production, as a depth field or something.