Are electronic shutters more accurate?
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If the electronics are doing one thing and the mechanics another, then there is reason enough for checking and adjusting (the mechanics that is).
The electronics may be regulated very differently. The most basic circuit uses a resistor and capacitor as timer. The capacitator might age, the resistor less, but as it is a variable one or a switched array, contact resistance may vary over time.
More advanced timers use an internal (quartz) clock and calculate time from this.
But basically electronic shutters can be more accurate.
The electronics may be regulated very differently. The most basic circuit uses a resistor and capacitor as timer. The capacitator might age, the resistor less, but as it is a variable one or a switched array, contact resistance may vary over time.
More advanced timers use an internal (quartz) clock and calculate time from this.
But basically electronic shutters can be more accurate.
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Mechanical shutters that are electronically controlled especially ones that use quartz crystal are significantly more accurate than the mechanical only counterpart especially in the slow speed (1/250 to 1 seconds or longer). Not so much for the speed above 1/1000 due to the fact that these speeds are greatly affected by the curtain travel time which is spring powered in either version. The adjustments generally first the spring tension to get the first and second shutter curtains travel time. Then the timing is adjusted via potentiometers or with more modern camera via software. For example the speeds of the Nikon F3 are adjusted using potentiometer. The speeds on the Nikon F5 is adjusted via software.
I know this thread is about focal plane shutters on 35mm cameras, but for future searchers I thought it might be helpful. I have a Schneider 210mm lens in a Compur electronic shutter. On most speeds it is quite a bit more accurate and repeatable than regular leaf shutters. Except: the low speeds, 1/2 sec and bellow are wildly inaccurate but perfectly repeatable, so I write a chart. My shutter tester is indispensable!
Who said so?
I checked my 30 year old N6006 Nikon and the electronic shutter was right on. I was very surprised considering its age.
Cameras like the EOS 3 and 1V have shutters controlled with magnets or whatever, so no springs to be tensioned and drift. The F5/F100/F6 are probably the same story.
Shutters on Leica's mechanical cameras (M3, M5, M6, M-A etc) 1/1000 sec speed times closer to 1/750.
The M7 - electronically controlled shutter - is much more accurate. But still not as accurate as electronically controlled vertical traveling shutters. Dean's Camera repair in Torrance put mine on his shutter timer/calibrator machine because he was curious.
The M7 - electronically controlled shutter - is much more accurate. But still not as accurate as electronically controlled vertical traveling shutters. Dean's Camera repair in Torrance put mine on his shutter timer/calibrator machine because he was curious.
As a side note, stepless electronic shutters allow for much greater exposure accuracy when shooting slide film.
In general terms, most cameras that control exposure time mechanically use either an escapement or some form of inertia retard mechanism, or a combination of both, especially for slower speeds. For inertia retard alone, there is usually some type of weight that, once the shutter is open, must be overcome to allow the shutter to close. Simple inertia retard mechanisms may provide only two speeds, for example, a "fast" speed where the blades open and close without impediment, and a "slow" speed where a weight must be overcome for the shutter to close.
An escapement is, for all intents, simply a series of gears, often with a "pallet and star wheel", with a portion that must be pushed aside to allow the shutter to close. The gear train and/or pallet may be combined via some sort of mechanism to vary the exposure time delivered. For example, for one relatively "fast" speed, only one gear of the escapement may be left in train, whereas progressively longer speeds may combine more gears in the train, then one star wheel, then a pallet for the slowest speed.
These mechanical mechanisms are somewhat variable, depending on design quality and of course cleanliness and condition. Most major manufacturers expected their designs to function well within ANSI standards, usually no more than +/- 30 percent of designated exposure. In cases where these tolerances are exceeded, most equipment can be disassembled, cleaned and re-lubricated, then adjusted to provide accurate operation.
(More obscure models may use even more unusual devices such as pneumatic delay mechanisms, but these are understandably rare.)
With most electronic controlled shutters, the exposure time is controlled by an electromagnet of some sort that delays the shutter closing, with a timing circuit that can be adjusted very precisely, often within single digit errors. These circuits are often initiated by electronic switches that signal the circuit to begin timing, while fixed speeds are often set using stepped resistance inputs. In both cases, the switches that begin the exposure and the connections that select these fixed values sometimes become tarnished with age, resulting in variable and erratic speeds in older cameras. In these cases, simply "adjusting" a camera is seldom successful or appropriate -- the switches and contacts should be cleaned and serviced to assure proper function before any adjustments are made.
An escapement is, for all intents, simply a series of gears, often with a "pallet and star wheel", with a portion that must be pushed aside to allow the shutter to close. The gear train and/or pallet may be combined via some sort of mechanism to vary the exposure time delivered. For example, for one relatively "fast" speed, only one gear of the escapement may be left in train, whereas progressively longer speeds may combine more gears in the train, then one star wheel, then a pallet for the slowest speed.
These mechanical mechanisms are somewhat variable, depending on design quality and of course cleanliness and condition. Most major manufacturers expected their designs to function well within ANSI standards, usually no more than +/- 30 percent of designated exposure. In cases where these tolerances are exceeded, most equipment can be disassembled, cleaned and re-lubricated, then adjusted to provide accurate operation.
(More obscure models may use even more unusual devices such as pneumatic delay mechanisms, but these are understandably rare.)
With most electronic controlled shutters, the exposure time is controlled by an electromagnet of some sort that delays the shutter closing, with a timing circuit that can be adjusted very precisely, often within single digit errors. These circuits are often initiated by electronic switches that signal the circuit to begin timing, while fixed speeds are often set using stepped resistance inputs. In both cases, the switches that begin the exposure and the connections that select these fixed values sometimes become tarnished with age, resulting in variable and erratic speeds in older cameras. In these cases, simply "adjusting" a camera is seldom successful or appropriate -- the switches and contacts should be cleaned and serviced to assure proper function before any adjustments are made.
Thank you for such a detailed and easy to understand, explanation.
Yes there are springs that actually move the shutter curtain. The magnets are to hold the shutter against the spring before they are released. They still have the the springs to power the curtain but no escapement for timing.
My bad! Please accept my apology! The Canon used rotary magnets to move the shutter curtain. So the adjustment is totally closed case via software only. That's cool. But I know that the F5 has springs and doesn't have rotary magnets (I am a Nikon user)
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The best example I can think of is the Pentax LX. The LX has a hybrid electronic-mechanical shutter. In manual mode, speeds 1/75th (x-sync) to 1/2000th are mechanically controlled (and work without a battery), slower speeds are electronically timed. When tested back in the day, the electronic speeds were more accurate than the mechanical ones (which were still within suitable tolerances). This is the same shutter in the same camera at the same time.
In Av mode you can't compare as the speeds are stepless and the metering meters off the film plane during the exposure.
In Av mode you can't compare as the speeds are stepless and the metering meters off the film plane during the exposure.
The FM3A also has a hybrid shutter, with all the speeds being electronic when the batteries are good, and mechanical with no batteries.
I believe the electronic shutter speed is adjustable on some cameras -- repair manuals will tell you more.
But as others have said, once set at the factory, electronic shutters rarely go out of adjustment. Gooping-up of lubricant or dirt on electromagnets could, in theory, cause timing changes, but mostly they're pretty accurate -- not subject to the drift of mechanical shutters. In my experience, if a camera with an electronic shutter works at all, it probably works properly.
Also, as pointed out, when used in aperture-priority automatic mode they are stepless and variable, so they can shoot at any speed required for the exposure (1/40th or 1/564th or 1/1298th) so can give much more exacting exposures than an all-mechanical camera.
Aaron
If flash is not in use they last long and capacity indicator is accurate. If you are paying attention to it here is no awkward times.
In my experience ,electronic shutters are far more accurate than mechanical shutters but, both are within practical accuracy for many years.
Deleted member 88956
electronic shutters: accuracy and long term repeatability (provided nothing went wrong with critical components, so not buy and rest forever).
mechanical shutters: cool, but require more therapy over time to run as designed, but still ... cool.
mechanical shutters: cool, but require more therapy over time to run as designed, but still ... cool.
If you’re familiar at all with control systems theory, in general at this size mechanical systems run open loop. The shutters we use are no exception, and are thus susceptible to loss of accuracy as components age and wear. Electrical systems are easier to implement closed-loop and can this be made more accurate. Historically, I believe closed loop electronic shutter systems were implemented towards the end of the 90s for 35mm. I know at least the Nikon shutter design that went into the F5, F6, etc were closed-loop control systems and thus guaranteed extreme accuracy for the lifetime of the shutter.
Closed loop then means that there are sensor checking on the shutter opening and closing. Are there such?
The AE-1 was the first camera with digital control. The shutter magnets being contolled based on a quartz clock. But this lacks effect if the shutter curtains stick at their magnets or run slow.
The AE-1 was the first camera with digital control. The shutter magnets being contolled based on a quartz clock. But this lacks effect if the shutter curtains stick at their magnets or run slow.
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