SLR, mirror, and mirrorless discussion

Besides nostalgia and optical viewfinder, what advantage does mirror provide in camera body design?

rxjohn wrote in post #16743162
Besides nostalgia and optical viewfinder, what advantage does mirror provide in camera body design?

Anyone who insists on using a camera to track a rapidly moving subject knows the answer. Reflex viewfinders remain the most effective and accurate camera framing devices. That's been the case since the single-lens reflex camera first became popular in the 1940's. It's why the
SLR design has been the method of choice for cameras from companies as varied as Minolta, Pentax, Polaroid and Hasselblad.

If your interest is in photographing static subjects, other view finders (especially the currently fashionable EVF) may be useful, but the mirror prism viewfinder is still the best for those who need absolute framing accuracy with no electronic interference.

rxjohn wrote in post #16743162
Besides nostalgia and optical viewfinder, what advantage does mirror provide in camera body design?

The mirror allows the optical viewfinder to see through the same lens used to form the image. Optical viewfinders that do not use mirrors suffer from parallax and are generally not able to compensate for changes in focal length like when they are used with zoom lenses. That is the purpose of the mirror, it is there for the optical viewfinder.

Are you asking what the purpose of an optical viewfinder is? Because if you don't have an optical viewfinder, then you don't need a mirror. The question feels kind of backwards in statement or something.

We have always heard about Live View exhibiting the disadvantage of increased sensor noise as the constant activation of the sensor heats it up. So why would a mirrorless camera not also be subject to the same sensor heat noise issues?!

The reflex system also has the least lag time between shutter activation and image capture. This has significant advantages when capturing moving subjects.

While the twin-lens reflex (TLR) has a theoretical lag-time advantage, this advantage is defeated by the leaf shutter used in such systems. The leaf shutter has other advantages, but lag time is not among them.

This leaves the single-lens reflex (SLR) as the system of choice for sports, wildlife, and other photography where a minimal lag time is desired. The action of the focal-plane shutter used in the majority of SLR cameras is both quick and accurate.

Additionally, the SLR offers a relatively rapid and inexpensive interchangeable lens capability and a viewfinder system that shows exactly what the camera will capture, with no parallax errors.

Granted, other camera system may be superior for specialized types of photography, but the SLR reigns supreme for general and moving-subject photography.

Wilt wrote in post #16743357
We have always heard about Live View exhibiting the disadvantage of increased sensor noise as the constant activation of the sensor heats it up. So why would a mirrorless camera not also be subject to the same sensor heat noise issues?!

It is.

20droger wrote in post #16743365
The reflex system also has the least lag time between shutter activation and image capture. This has significant advantages when capturing moving subjects.

While the twin-lens reflex (TLR) has a theoretical lag-time advantage, this advantage is defeated by the leaf shutter used in such systems. The leaf shutter has other advantages, but lag time is not among them.

Mirrorless reflex systems like the EOS RT had very brief shutter lag times. But I have never seen anything published about shutter lag inherent to the use of a leaf shutter in a non-reflex system (e.g. rangefinder camera). Have you some information about leaf shutter lag?
I understand leaf shutters in reflex systems...the leaf shutter has to close, then the mirror flips up out of the way, then the shutter opens...the first step creates inherent delays not required of focal plane shutter reflex designs.

OVF advantages:
1. Resolves as much detail as your eye can see
2. Doesn't lag in low light
3. Doesn't use battery power
4. You can actually see in low light
5. No flicker under fluorescent light

EVF advantages:
1. What you see is what you get
2. You can magnify the finder
3. More visual information
4. You can look at extremely bright objects
5. Often results in a smaller/lighter camera

JeffreyG wrote in post #16743354
Are you asking what the purpose of an optical viewfinder is? Because if you don't have an optical viewfinder, then you don't need a mirror. The question feels kind of backwards in statement or something.

He's asking about cameras with mirrors versus mirrorless cameras like the A7 or A99

Wilt wrote in post #16743357
We have always heard about Live View exhibiting the disadvantage of increased sensor noise as the constant activation of the sensor heats it up. So why would a mirrorless camera not also be subject to the same sensor heat noise issues?!

It's an interesting question, and I think we may start to see actively cooled cameras as full-frame mirrorless cameras become more common, the small sensors used in compact cameras likely don't generate enough heat for it to matter. To my knowledge, many mirrorless cameras do automatically shut off if the sensor overheats.

Wilt wrote in post #16743413
Mirrorless reflex systems like the EOS RT had very brief shutter lag times. But I have never seen anything published about shutter lag inherent to the use of a leaf shutter in a non-reflex system (e.g. rangefinder camera). Have you some information about leaf shutter lag?
I understand leaf shutters in reflex systems...the leaf shutter has to close, then the mirror flips up out of the way, then the shutter opens...the first step creates inherent delays not required of focal plane shutter reflex designs.

In theory, mirrorless cameras should have less shutter lag since there's less mechanics, but for various reasons ultimately both OVF and EVF cameras have some amount of shutter lag to them. The difference is that EVFs tend to "freeze" during the moment of exposure, while OVFs black out. Personally, I find the freezing effect somewhat disorienting.

Kolor-Pikker wrote in post #16743419
He's asking about cameras with mirrors versus mirrorless cameras like the A7 or A99

Ah, perhaps the flaw is that the people who named these cameras 'mirrorless' missed the mark. The distinction isn't that they lack mirrors (I've had optical viewfinder cameras without mirrors) but that they have an electronic viewfinder.

I mean....were we all sitting around thinking "These darn mirrors sure are annoying" which brought us to a camera with an electronic viewfinder?

I don't care if the camera has a mirror or not. I just want what OVFs deliver (no lag, no freezing, eye-limited resolution and TTL viewing) with what EFV's promise at some point (WYSIWYG with regards to exposure, plus histogram etc).

Deleting the mirror isn't the point.

JeffreyG wrote in post #16743441
I mean....were we all sitting around thinking "These darn mirrors sure are annoying" which brought us to a camera with an electronic viewfinder?

Canon seems to have historically been particularly preoccupied with the concept of the reflex mirror slowing things down...first the Canon Pellix, then the Canon F-1 High Speed, then the Canon EOS RT

JeffreyG wrote in post #16743441
Ah, perhaps the flaw is that the people who named these cameras 'mirrorless' missed the mark. The distinction isn't that they lack mirrors (I've had optical viewfinder cameras without mirrors) but that they have an electronic viewfinder.

There was this word floating around the net a while back "EVIL" (Electronic Viewfinder, Interchangeable Lens), which was used to describe cameras like these. It seems to have fallen out of use lately, because it probably isn't marketable.

That said, I'm guessing that most people today have never used a mirrorless camera without an EVF, which is why some people use the term interchangeably.

This reminds me of when LCD monitors took over CRTs in 2001, it took another decade at least before LCDs reached the resolution and color accuracy of tube monitors, and they still can't quite match motion and black level even now.

It's going to take a while longer for sure to see what happens, unlike CRTs, where development came to a global standstill, OVFs continue to get more advanced alongside EVFs.