How Your Camera Really Works

[endure]

[Guest]

There is two things I don't understand.

1) What is the flipping lens?

2) I'm very surprised that there are mechanical parts on the cameras (the flipping lens and shutter).

Or was this an Friday feel good post?

[richard_smith237]

Its an SLR Camera... with film.

The flipping lens is the mirror usually directing the image through to the eye piece...

The mechanical part behind the mirror is the shutter mechanism which varies according to exposure time.

In principle its very simple. In reality its a work of engineering art.

[Tywais]

There is two things I don't understand.

1) What is the flipping lens?

2) I'm very surprised that there are mechanical parts on the cameras (the flipping lens and shutter).

Or was this an Friday feel good post?

That is how film SLRs have worked for decades. The high end dSLRs also. This is due to the use of true optical viewfinder which many find superior to the digital representation used in many view finders today though that is improving significantly. Since it is an optical viewfinder (disregarding rangefinders) it has a mirror in front that reflects the image up to a prism then back out the eye piece. The mirror has to move out of the way (the 'flipping' as you mention) then the curtain is opened and closed which allows the light to expose the film/sensor. What is remarkable, is the speed it can move the mirror out of the way to get fast exposure shots.

If you have used film SLRs you will remember that very notable sound of the mirror flipping. And you will hear that same sound simulated digitally in even point and shoot cameras. Even my camera phone makes the same shutter sound.

Pros: optical view finder

The advantages of the OVF are that the photographer sees a scene with no

time lag, no resolution limits, and with all the clarity the lens and

the human eye can produce. Sports shooters rely on this system to see

action immediately and anticipate the kind of timing necessary to

capture the right moment. OVFs also save battery since looking through

them doesn’t require any charge, and the photographer can take time to

compose a shot before turning the camera on. And anyone who has tried to

use an LCD screen in bright sunlight can appreciate that eye-level

viewfinders aren’t affected by reflections.

Source

Using an optical viewfinder can improve your photography

[Guest]

I did not realise that it was old film camera and definitively agree that it's engineering art. Is there still some mechanical moving parts in digital cameras? I don't mean the push buttons, but shutters etc.

If not, how those functions are done today? What makes the limitations of the fastest shutter speeds on today's cameras? Some can do 1/2000 some faster.

On the old cameras, there used to be batteries as far as I can remember (my father was not happy to buy those very expensive batteries to his camera a loong time ago

How did the shutter work? Battery charged an capacitor, which charged an electrical magnet to lift and shut the shutter?

I'm sorry if I don't know how to ask the right questions, as this is new area for me. Just wish to learn more.

[Tywais]

I did not realise that it was old film camera and definitively agree that it's engineering art. Is there still some mechanical moving parts in digital cameras? I don't mean the push buttons, but shutters etc.

If not, how those functions are done today? What makes the limitations of the fastest shutter speeds on today's cameras? Some can do 1/2000 some faster.

Not just legacy SLR film cameras but most dSLRs also use the exact same technology such as Canon 5D Mark series.

Like SLRs DSLRs typically use interchangeable lenses (1) with a proprietary lens mount. A movable mechanical mirror system (2) is switched down (exact 45-degree angle) to direct light from the lens over a matte focusing screen (5) via a condenser lens (6) and a pentaprism/pentamirror (7) to an optical viewfinder eyepiece (8). Most of the entry level DSLRs use a pentamirror instead of the traditional pentaprism. The pentamirror design is composed mostly of plastic and is lighter and cheaper to produce — however, the image in the viewfinder is usually darker.

Source Wiki dSLR

One minor disadvantage is they have a limited shutter life due to being mechanical. Your P&S and many other digitals use electronic shutters. For example, the Mark iii has an effective 150,000 shutter operations lifetime. Behind the mirror are the curtain(s). Some have more than one such and you will see specs such as 1st curtain, 2nd curtain operation. This allows for higher shutter speeds.

If you set your camera on a shutter time of one second, you can hear all

of this going on inside. The initial slap of the mirror moving out of

the way and the first curtain click are often very close. Then after the

one second you will hear the second curtain activate followed by the

mirror dropping and the whole mechanism resetting.

Read more: http://digital-photography-school.com/how-a-typical-dslr-shutter-works#ixzz2Le58gEYj

[Tywais]

One thing I may have made confusing and that the actual curtain (shutters) are what determine how fast an exposure can be made. They are extremely light weight and can be opened/closed very fast. The mirror just moves out of the way and the curtains do the exposing. The mirror speed limits the shots per second such as 5fps due to the mass but not the actual exposure time.

//edit - BTW, the clip endure shows is of a modern high end Canon 5D Mark II dSLR and not a film camera.

[endure]

The camera in the video is a Canon 5D Mk II full frame digital SLR.

[Guest]

But to drop an object with gravity. Just for 1cm would take quite a longer time that the shutter is doing. I'm now too tired to do any calculations, but I would think that to drop an free fall object it would take at least 0.1 seconds for the first 1cm. That's 1/10 seconds shutter speed.

There has to be something else which is moving the shutter up and down to reach 1/2000s speeds.

When I looked at the video and the thinness of the shutter as well as the mirror, it's amazing that those parts can work reliably for more than 10 time, not to forget the 150.000 times mentioned before. Just amazing engineering work.

[Guest]

And I don't understand why to use physical shutter in modern cameras? Wouldn't it be much more easy to do the same electrically? Just read the sensor data when the button is pushed while 'shutter speed' would be just the amount of time how long the light is collected.

[fimgirl]

And I don't understand why to use physical shutter in modern cameras? Wouldn't it be much more easy to do the same electrically? Just read the sensor data when the button is pushed while 'shutter speed' would be just the amount of time how long the light is collected.

See this link

http://www.steves-digicams.com/knowledge-center/why-digital-cameras-have-mechanical-shutters.html

[Tywais]

But to drop an object with gravity. Just for 1cm would take quite a longer time that the shutter is doing. I'm now too tired to do any calculations, but I would think that to drop an free fall object it would take at least 0.1 seconds for the first 1cm. That's 1/10 seconds shutter speed.

See my post #7. It explains the mirror motion and the shutter are separate ports of the puzzle. Your .1 S analogy would be how many shots per second that can be taken (10 fps in the .1S example) but not related to the actual shutter open/close time which determines the exposure time.

[Tywais]

And I don't understand why to use physical shutter in modern cameras? Wouldn't it be much more easy to do the same electrically? Just read the sensor data when the button is pushed while 'shutter speed' would be just the amount of time how long the light is collected.

See this link

http://www.steves-digicams.com/knowledge-center/why-digital-cameras-have-mechanical-shutters.html

Good explanation.

[Guest]

And I don't understand why to use physical shutter in modern cameras? Wouldn't it be much more easy to do the same electrically? Just read the sensor data when the button is pushed while 'shutter speed' would be just the amount of time how long the light is collected.

See this link

http://www.steves-digicams.com/knowledge-center/why-digital-cameras-have-mechanical-shutters.html

Thanks, that addressed the question pretty well. But few more question arises

If I understood correctly, the sensor 'pixels' are charged by incoming light and then read by the processor when the picture is taken. So there has to be start and stop for this. There is no flush all and read all option.

Smaller sensors can afford to have 'memory' where the charge is stored and read later on. This however reduces the ability to collect light aka charge as the collection cells and memory cells are next to each other. Is there a way to make sensors where the memory cells are behind of the collection cells?

Full frame sensors are just collecting light, which is controlled by the manual shutter. When taking images with very fast shutter speed, is there a difference between the bottom of the picture and top of the picture as the shutter will take it's time to move up and down?

There are also some 'lcd type' of windows, which are or will be used in meeting rooms to blur the view from outside to the room. Could this kind of technology be used as shutters? Something like this, but faster and much darker http://www.esgpolyvision.co.uk/glass_solutions.html

[Guest]

But to drop an object with gravity. Just for 1cm would take quite a longer time that the shutter is doing. I'm now too tired to do any calculations, but I would think that to drop an free fall object it would take at least 0.1 seconds for the first 1cm. That's 1/10 seconds shutter speed.

See my post #7. It explains the mirror motion and the shutter are separate ports of the puzzle. Your .1 S analogy would be how many shots per second that can be taken (10 fps in the .1S example) but not related to the actual shutter open/close time which determines the exposure time.

The analogy of 0.1 second was to think how long an first static, free fall object would take to drop 1cm when affected only by gravity.

I would think that the mirror flip speed explains the speed difference between 1 shot and multiple shots at one go. It takes more time to flip the mirror up and down than moving the shutter up and down. When there is multiple shots at one go, the mirror stays up and it's not possible to see the image from the viewfinder at the same time as the mirror does not drop down during this time. Still the shutter moves up and down between each shot.

But how to move the shutter up and down within 1/1000 of second? Using magnets?

[endure]

If you're using the continuous shooting method with an SLR the mirror does move up and down between each shot. You can see the image in the viewfinder between shots.

[FracturedRabbit]

Early cameras were entirely mechanical. This is a 1950 Kiev 2 (which was a Contax until the Russians took over the Contax factory at the end of the second world war and moved production to Kiev):

P1070499-Edit-2 by pattayadays.com, on Flickr

It's a rangefinder which will take a variety of lenses. The turret on the top can be rotated to show the field of view for different focal lengths. The view through the rangefinder is a little cloudy nowadays, but it still focuses accurately.

I also bought a couple of broken models so I could partially dismantle them and have a look at what was going on inside. Extremely complex 1930's mechanical design!

The winder and shutter mechanism by pattayadays.com, on Flickr

P1070482-Edit by pattayadays.com, on Flickr

P1070484-Edit by pattayadays.com, on Flickr

P1070472-Edit by pattayadays.com, on Flickr

Having taken one to pieces and studied the internals at length, I still have no idea how it works!

But 60+ years on, and the Kiev can still take photos, I doubt many modern cameras will be functional in sixty years time:

Scan-120926-0005 by pattayadays.com, on Flickr

Moving forward in history a little, a friend has lent me an Olympus OM-1 from the 1970s. This does take a battery, but only for the light meter. Without a battery, the camera is entirely mechanical and will still takes photos. Here it is sat next to its spiritual successor, the OM-D E-M5.

P1160964 by pattayadays.com, on Flickr

[Guest]

These two links gives good explanations how the shutter works. Two curtains and the release time difference will give the shutter speed.

http://digital-photography-school.com/how-a-typical-dslr-shutter-works

And video