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Excuse me for this very uninformed question, but (D)SLR, as far as I can tell, is about using a prism to split light, to allow having a viewfinder. Why does a

Excuse me for this very uninformed question, but (D)SLR, as far as I can tell, is about using a prism to split light, to allow having a viewfinder. Why does a digital camera need a prism for it, can't the digital sensor directly show the image on screen (or viewfinder, do photographers still look through a viewfinder?) Or does DSLR stand here for any camera with exchangeable lenses? Does the article mean professional cameras with exchangeable lenses are dead?

Lio 5y ago
Yep totally possible, that’s what a mirrorless camera like micro-4/3 does. Many DSLRs also let lock the mirror up and just view via sensor. In theory running the sensor continuously generates heat that can lead to image noise. Realistically though the sensors are now so good that you don’t need to worry about it.
frostburg 5y ago
Digital cameras don't really need it but DSLR cameras needed the apparatus for phase detection autofocus anyway. This isn't really a concern anymore.
tticvs 5y ago
What you are describing is called a "mirrorless" camera which is what the article says will be the future. They also have interchangeable lenses, but there are less constraints on the design since they don't have to interface with another optical system, just the digital sensor, which is the main point the article is trying to make.
zimpenfish 5y ago
> can't the digital sensor directly show the image on screen A bunch of them do - https://en.wikipedia.org/wiki/Electronic_viewfinder https://en.wikipedia.org/wiki/Electronic_viewfinder - but a screen or viewfinder isn't going to have the same kind of resolution as your eyes when you're trying to judge focus/DoF/etc.
hylaride 5y ago
A digital camera doesn’t need a prism…anymore. When DSLRs first came to market two decades ago, they didn’t do video. Even if they did, the batteries at the time wouldn’t have held up for long shoots for weddings, sporting events, etc if they were showing video in the screen. As the article states, the move to mirrorless cameras is now pretty much a given. Canon announced their latest DSLR will be the last.
dale_glass 5y ago
Several reasons: * Until fairly recently, cameras couldn't focus well using just the sensor. The simple sensor-based focusing is based on contrast, and the problem with the method is that the camera can't tell whether it's as focused as it can get, or in which direction should focus be changed. So the camera constantly "hunts". You can see that happening a lot on youtube with people trying to show stuff from close (eg, Bosnian Bill, AvE very often have this problem). * Phase focusing fixes this issue, but initially couldn't be incorporated into the sensor. The mirror in DSLRs bounces light into the better focus detectors, which are located on the bottom of the camera. Here's an illustration of the system: https://photographylife.com/how-phase-detection-autofocus-works https://photographylife.com/how-phase-detection-autofocus-wo... * Sensors get hot when they're constantly lit. Cameras refuse to keep taking pictures when it overheats. A DSLR's sensor can cool off while the mirror is blocking it. * Sometimes the viewfinder is the better way, eg, if the LCD can't overpower the sun. Making a good digital viewfinder is harder than just optics. * An optical viewfinder has no lag and almost zero battery usage But yes, mirrorless is definitely the future. The DSLR was a technical compromise, and in fact mirrorless has advantages of its own: * As this article says, DSLRs require a large separation between the sensor and lens to make room for the mirror, and that makes some kinds of lenses hard to design. Mirrorless cameras can use whatever distance works best. * Also, the mirror is a pretty delicate, very quickly moving piece that creates vibration, and this needs taking into account. It's common to incorporate a delay to allow for vibration to settle, or to use a special mode where the mirror is permanently kept up for the cases in which vibration needs to be minimized. Mirrorless cameras don't have a moving mirror, so this is not an issue.
rileyphone 5y ago
Photographers definitely still need viewfinders, but only recently did the pixel densities of digital ones reach the point where they are an acceptable replacement for looking directly through the lens. This also means mirrorless cameras can add features to the viewfinder like focus peaking (highlighting the areas that are focused).
treis 5y ago
>Excuse me for this very uninformed question, but (D)SLR, as far as I can tell, is about using a prism to split light, to allow having a viewfinder. They have a mirror that reflects light to the view finder. The mirror flips out of the way to let the light hit the sensor. What you describe are called mirror less and is the revolution the article is about. They've been around for a while now but the combination of sensor, battery, and screen improvements have finally reached the point where the disadvantages are mostly gone.
LegitShady 5y ago
>Or does DSLR stand here for any camera with exchangeable lenses? Does the article mean professional cameras with exchangeable lenses are dead? No. By removing the mirror-prism system as mirrorless cameras with interchangeable lenses have, you can bring the lens a lot closer to the sensor which opens up design choices that couldn't happen during the SLR or DSLR era. That's exactly what the article is describing. The article just does a fairly subtle job of explaining it: >These new lenses and lens mounts differ in one special way from previous generations. They aren’t limited by the design of the camera. The distance between the sensor and lens can be whatever the manufacturer wants it to be for the best results. With that limitation out of the way, lenses can embrace the advantages of rangefinder lenses, without their disadvantages. That being said its going to be a while before I declare DSLRs dead, because the great majority of people will be extraordinarily well served by a modern SLR, and I buy all my camera equipment used anyways.
crote 5y ago
A screen on the back of a camera is lit up by the environment, so it needs to be extremely bright to work properly in direct sunlight while also having zero backlight bleed in near darkness. Viewfinders solve this issue. The problem with live preview from a digital sensor is that the sensor needs to be able to stream the entire image constantly. Early sensors were not designed for this, and would often overheat quite quickly. It also needs to update often enough to not be jittery, and in low light conditions early digital sensors just weren't sensitive enough. You also need an extremely high-resolution viewfinder screen to provide enough detail for things like focus. Those didn't exist yet either. One thing to keep in mind is that it was definitely possible: consumer cameras did it quite early on! But the quality was quite poor: good enough for holiday snapshots, but not nearly good enough for professional photographers. Sticking to the DSLR approach was a no-brainer for them. Also, a (D)SLR doesn't split light: a mirror flips down in front of the sensor to reflect the light into the viewfinder. When you take an image the mirror flips up, allowing light to fall onto the sensor.
- nayuki 5y ago
  > a (D)SLR doesn't split light It actually does. When you're not taking a picture, the main mirror is down. But there is a translucent part of the main mirror that goes to a secondary mirror that goes to the autofocus sensor below. https://keyassets.timeincuk.net/inspirewp/live/wp-content/uploads/sites/12/2011/07/Focusing_explained.jpg https://keyassets.timeincuk.net/inspirewp/live/wp-content/up... ; https://www.amateurphotographer.co.uk/technique/how-focusing-works-16250 https://www.amateurphotographer.co.uk/technique/how-focusing... ; https://alison.com/course/1326/resource/file/resource_200-1497623822678657349.pdf#page=5 https://alison.com/course/1326/resource/file/resource_200-14... Moreover, there are camera designs with a fixed mirror that always splits between the main sensor and AF sensor (but not viewfinder): https://en.wikipedia.org/wiki/Sony_SLT_camera https://en.wikipedia.org/wiki/Sony_SLT_camera
nayuki 5y ago
The film SLR was the predecessor of DSLRs. Back then, you basically had two choices - preview through a different lens than you shoot with (twin-lens reflex, rangefinder), or preview through the same lens that you shoot with (single-lens reflex). In an SLR design, you need a way to swap between the light path to the film versus the light path to the viewfinder, and a mirror and prism is the most practical way to do so. Yes, a DSLR can simply show in real time what is being captured on the sensor - this is called "live view" and was introduced some years after the first DSLR, as it's not a critical feature. But live view drains a lot of battery. It also had terribly slow and inaccurate autofocus using contrast detection, but was improved using phase detection (e.g. Canon DPAF). Another consideration is that live view takes a second or two to start up, whereas most DSLRs will let you pick up a camera from idle and shoot through the viewfinder in a fraction of a second. > any camera with exchangeable lenses These are called interchangeable-lens cameras (ILC), a category which has significant overlap with but isn't identical to DSLRs. > professional cameras with exchangeable lenses are dead? Mirrorless cameras with interchangeable lenses (MILC) are quickly becoming the new professional gear.
vmception 5y ago
Exactly it does not mean exchangeable lens, just the inferior mirror/prism technology is being killed. The article eventually becomes clear about that. Mirrorless cameras that look the same as DSLRs are still thriving.
kjkjadksj 5y ago
By not using a screen dslrs have 3x or more the battery life of a given mirrorless camera.

Lio 5y ago

Yep totally possible, that’s what a mirrorless camera like micro-4/3 does. Many DSLRs also let lock the mirror up and just view via sensor. In theory running the sensor continuously generates heat that can lead to image noise. Realistically though the sensors are now so good that you don’t need to worry about it.

frostburg 5y ago

Digital cameras don't really need it but DSLR cameras needed the apparatus for phase detection autofocus anyway. This isn't really a concern anymore.

tticvs 5y ago

What you are describing is called a "mirrorless" camera which is what the article says will be the future. They also have interchangeable lenses, but there are less constraints on the design since they don't have to interface with another optical system, just the digital sensor, which is the main point the article is trying to make.

zimpenfish 5y ago

> can't the digital sensor directly show the image on screen A bunch of them do - https://en.wikipedia.org/wiki/Electronic_viewfinder https://en.wikipedia.org/wiki/Electronic_viewfinder - but a screen or viewfinder isn't going to have the same kind of resolution as your eyes when you're trying to judge focus/DoF/etc.

hylaride 5y ago

A digital camera doesn’t need a prism…anymore. When DSLRs first came to market two decades ago, they didn’t do video. Even if they did, the batteries at the time wouldn’t have held up for long shoots for weddings, sporting events, etc if they were showing video in the screen. As the article states, the move to mirrorless cameras is now pretty much a given. Canon announced their latest DSLR will be the last.

dale_glass 5y ago

Several reasons: * Until fairly recently, cameras couldn't focus well using just the sensor. The simple sensor-based focusing is based on contrast, and the problem with the method is that the camera can't tell whether it's as focused as it can get, or in which direction should focus be changed. So the camera constantly "hunts". You can see that happening a lot on youtube with people trying to show stuff from close (eg, Bosnian Bill, AvE very often have this problem). * Phase focusing fixes this issue, but initially couldn't be incorporated into the sensor. The mirror in DSLRs bounces light into the better focus detectors, which are located on the bottom of the camera. Here's an illustration of the system: https://photographylife.com/how-phase-detection-autofocus-works https://photographylife.com/how-phase-detection-autofocus-wo... * Sensors get hot when they're constantly lit. Cameras refuse to keep taking pictures when it overheats. A DSLR's sensor can cool off while the mirror is blocking it. * Sometimes the viewfinder is the better way, eg, if the LCD can't overpower the sun. Making a good digital viewfinder is harder than just optics. * An optical viewfinder has no lag and almost zero battery usage But yes, mirrorless is definitely the future. The DSLR was a technical compromise, and in fact mirrorless has advantages of its own: * As this article says, DSLRs require a large separation between the sensor and lens to make room for the mirror, and that makes some kinds of lenses hard to design. Mirrorless cameras can use whatever distance works best. * Also, the mirror is a pretty delicate, very quickly moving piece that creates vibration, and this needs taking into account. It's common to incorporate a delay to allow for vibration to settle, or to use a special mode where the mirror is permanently kept up for the cases in which vibration needs to be minimized. Mirrorless cameras don't have a moving mirror, so this is not an issue.

rileyphone 5y ago

Photographers definitely still need viewfinders, but only recently did the pixel densities of digital ones reach the point where they are an acceptable replacement for looking directly through the lens. This also means mirrorless cameras can add features to the viewfinder like focus peaking (highlighting the areas that are focused).

treis 5y ago

>Excuse me for this very uninformed question, but (D)SLR, as far as I can tell, is about using a prism to split light, to allow having a viewfinder. They have a mirror that reflects light to the view finder. The mirror flips out of the way to let the light hit the sensor. What you describe are called mirror less and is the revolution the article is about. They've been around for a while now but the combination of sensor, battery, and screen improvements have finally reached the point where the disadvantages are mostly gone.

LegitShady 5y ago

>Or does DSLR stand here for any camera with exchangeable lenses? Does the article mean professional cameras with exchangeable lenses are dead? No. By removing the mirror-prism system as mirrorless cameras with interchangeable lenses have, you can bring the lens a lot closer to the sensor which opens up design choices that couldn't happen during the SLR or DSLR era. That's exactly what the article is describing. The article just does a fairly subtle job of explaining it: >These new lenses and lens mounts differ in one special way from previous generations. They aren’t limited by the design of the camera. The distance between the sensor and lens can be whatever the manufacturer wants it to be for the best results. With that limitation out of the way, lenses can embrace the advantages of rangefinder lenses, without their disadvantages. That being said its going to be a while before I declare DSLRs dead, because the great majority of people will be extraordinarily well served by a modern SLR, and I buy all my camera equipment used anyways.

crote 5y ago

A screen on the back of a camera is lit up by the environment, so it needs to be extremely bright to work properly in direct sunlight while also having zero backlight bleed in near darkness. Viewfinders solve this issue. The problem with live preview from a digital sensor is that the sensor needs to be able to stream the entire image constantly. Early sensors were not designed for this, and would often overheat quite quickly. It also needs to update often enough to not be jittery, and in low light conditions early digital sensors just weren't sensitive enough. You also need an extremely high-resolution viewfinder screen to provide enough detail for things like focus. Those didn't exist yet either. One thing to keep in mind is that it was definitely possible: consumer cameras did it quite early on! But the quality was quite poor: good enough for holiday snapshots, but not nearly good enough for professional photographers. Sticking to the DSLR approach was a no-brainer for them. Also, a (D)SLR doesn't split light: a mirror flips down in front of the sensor to reflect the light into the viewfinder. When you take an image the mirror flips up, allowing light to fall onto the sensor.

nayuki 5y ago
> a (D)SLR doesn't split light It actually does. When you're not taking a picture, the main mirror is down. But there is a translucent part of the main mirror that goes to a secondary mirror that goes to the autofocus sensor below. https://keyassets.timeincuk.net/inspirewp/live/wp-content/uploads/sites/12/2011/07/Focusing_explained.jpg https://keyassets.timeincuk.net/inspirewp/live/wp-content/up... ; https://www.amateurphotographer.co.uk/technique/how-focusing-works-16250 https://www.amateurphotographer.co.uk/technique/how-focusing... ; https://alison.com/course/1326/resource/file/resource_200-1497623822678657349.pdf#page=5 https://alison.com/course/1326/resource/file/resource_200-14... Moreover, there are camera designs with a fixed mirror that always splits between the main sensor and AF sensor (but not viewfinder): https://en.wikipedia.org/wiki/Sony_SLT_camera https://en.wikipedia.org/wiki/Sony_SLT_camera

nayuki 5y ago

The film SLR was the predecessor of DSLRs. Back then, you basically had two choices - preview through a different lens than you shoot with (twin-lens reflex, rangefinder), or preview through the same lens that you shoot with (single-lens reflex). In an SLR design, you need a way to swap between the light path to the film versus the light path to the viewfinder, and a mirror and prism is the most practical way to do so. Yes, a DSLR can simply show in real time what is being captured on the sensor - this is called "live view" and was introduced some years after the first DSLR, as it's not a critical feature. But live view drains a lot of battery. It also had terribly slow and inaccurate autofocus using contrast detection, but was improved using phase detection (e.g. Canon DPAF). Another consideration is that live view takes a second or two to start up, whereas most DSLRs will let you pick up a camera from idle and shoot through the viewfinder in a fraction of a second. > any camera with exchangeable lenses These are called interchangeable-lens cameras (ILC), a category which has significant overlap with but isn't identical to DSLRs. > professional cameras with exchangeable lenses are dead? Mirrorless cameras with interchangeable lenses (MILC) are quickly becoming the new professional gear.

vmception 5y ago

Exactly it does not mean exchangeable lens, just the inferior mirror/prism technology is being killed. The article eventually becomes clear about that. Mirrorless cameras that look the same as DSLRs are still thriving.

kjkjadksj 5y ago

By not using a screen dslrs have 3x or more the battery life of a given mirrorless camera.