Timeline for Why can't ISO, shutter and aperture speeds be controlled more precisely rather than sticking to a fixed scale?
Current License: CC BY-SA 3.0
15 events
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| Oct 10, 2017 at 13:19 | comment | added | Caleb | @MichaelClark I think we're on the same page. ;-) | |
| Oct 10, 2017 at 0:06 | comment | added | Michael C | @Caleb Again, it all depends upon exactly how precise one desires. For creative photography 1/6 stop is fine. For scientific research, 0.01 stops may not be precise enough. It's well documented that the aperture control in EF or µ4/3 lenses is more precise than mechanically linked lenses used by other systems. That is why Nikon finally broke down and started making "E" lenses with electronically controlled apertures. But even such electronically controlled lenses are not repeatably accurate to the same degree that much more expensive lab grade stuff is. Getting from .01 to .001 costs a lot. | |
| Oct 9, 2017 at 16:00 | comment | added | Caleb | @MichaelClark The fact that Nikon hasn't needed to do better than that backs up my assertion that finer control just isn't needed. But it surely would be possible to build apertures that are highly repeatable -- companies like Canon and Nikon are masters at building small stepper motors, which are inherently very accurate and repeatable. I don't know if EF lenses use stepper motors to drive the aperture, but either way, doing so wouldn't be "extremely expensive" by any reasonable standard. | |
| Oct 9, 2017 at 15:15 | comment | added | Michael C | @Caleb The problem with repeatability is on the mechanical side of the systems, not the control side. For example, the vast majority of Nikon lenses still use mechanical linkages for the camera to control the lens aperture. Even when the camera is set for the exact same Av, the mechanical slack in the system will cause each successive movement to be slightly different. What would be the point of controlling the aperture in 1/100 stop movements if the standard deviation for any particular movement of the aperture at the same setting is +/-1/6 stop? | |
| Oct 5, 2017 at 1:20 | comment | added | Caleb | @MichaelClark Consider the volume knob on a stereo. It might be marked in decibels, but nobody worries much about whether the markings are accurate -- it's enough that you can turn the volume up or down a little or a lot. And if the knob is at least repeatable -- the same setting gives the same volume -- that's as much as anyone other than a sound engineer would care about. I claim that kind of relative precision should be fairly cheap; more expensive absolute accuracy is less important. In any case, I think we agree that either way, that level of fine control wouldn't be helpful. | |
| Oct 4, 2017 at 21:24 | comment | added | Michael C | @Caleb Again, for finer control, one must be able to both aim for and hit the smaller target. It's the second part (actually hitting the target within a very tightly defined tolerance) that gets expensive very quickly. Creating very fine steps is meaningless if the accuracy of the system is several orders of magnitude less accurate. | |
| Oct 4, 2017 at 21:15 | comment | added | Caleb | @MichaelClark I doubt that most people ever wonder whether 1/100s f/8 on their camera gives exactly the same exposure as the same setting on any other camera. I can understand the OP's notion that finer control over those parameters might be useful, and that's independent of the camera's fidelity to an objective standard. That said, I think that the reality of the situation is that finer control really wouldn't be useful -- I've never heard anyone wish for an aperture a little smaller than f/1.4 and a little larger than f/1.6. | |
| Oct 4, 2017 at 18:18 | history | edited | Michael C | CC BY-SA 3.0 |
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| Oct 4, 2017 at 18:05 | comment | added | Michael C | @Caleb Without the ability to do so precisely, what exactly could be gained by setting apertures in 1/100 stop steps if the camera is only accurate to within 1/6 stop? As already mentioned, there are some benefits for creative cinematography (the ability to do "stepless" transitions from one setting to another while recording), but that doesn't really apply to still photography. | |
| Oct 4, 2017 at 18:03 | history | edited | Michael C | CC BY-SA 3.0 |
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| Oct 4, 2017 at 17:46 | comment | added | Caleb | @MichaelClark Perhaps we each understood the question differently. I think the OP's question is mostly about why exposure settings aren't continuously variable rather than broken into discrete and seemingly large steps. I don't think providing that capability would be expensive. You're right that calibrating each camera against a standard would be expensive, but that seems separate from the number of steps between f/1.4 and f/2. I don't think it's what the OP was asking about. | |
| Oct 4, 2017 at 17:31 | comment | added | Michael C | @Caleb - If you read the answer carefully that is not what it says. The expense comes from the expectation of precision with less than 0.01% variance from a target value, not from the ability to target an almost infinite number of values. But if your margin for error is around 1/12 stop what good does it do set steps every 1/48 stop? | |
| Oct 4, 2017 at 11:48 | comment | added | Caleb | The motors that control aperture in modern lenses could easily be made to stop anywhere along their range, and timers could be set to any arbitrary value. These things are controlled by software, so I doubt that expense is an important consideration. | |
| Oct 4, 2017 at 10:59 | comment | added | J... | Also, working with fixed intervals makes exposure very easy to keep figured in your head. A stop of aperture can be brought back with one click of ISO and two clicks of shutter, for example. Nevermind carrying figures in your head when it comes to the crunch. | |
| Oct 4, 2017 at 7:41 | history | answered | Michael C | CC BY-SA 3.0 |