What are the techincal advantages and disadvantages of mirrorless?

Question

The main doubt one can have about mirrorless is, I think that they do not provide ttl viewfinder. Is this a big disadvantage? In what way is it worst (or best) than classical reflex system?

What are the others advantages and disadvantages of a mirrorless compared to a reflex?

Have mirrorless a chance to replace reflex (at least for non pros) in the future?

Asked by Paolo

Answer

Advantages/Disadvantages of electronic viewfinders have been discussed in another question for completeness:

• Optical TTL viewfinders are pretty much as sharp as the lens (with small losses for the focus screen and prism). Electronic viewfinders have fixed resolution, which is currently lower than OVFs.
• OVFs update in realtime, EVFs have a fixed latency and refresh rate (time taken to process the image, number of updates per second).
• Coverage of OVFs is often less than 100%, eyepoint & dioptre adjustments are limited as is the apparent size and brightness of the viewfinder.
• Electronic viewfinders have the ability to preview colour balance and depth of field (without darkening the image), zoom the image, apply gain for night shots as well as the potential of overlaying a limitless amount of metadata (gridlines, live histogram etc.).

The principal advantages of an SLR (or SLT) system are

• Ability to have TTL viewfinder! (see above)
• Ability to direct light to phase detect AF sensor.

The disadvantages are:

• Size / weight
• Shorter backfocus distance, allows more compact wideangles, as well as mounting of a wide range of legacy lenses.
• Increased reliability (fewer moving parts).
• Noise / Mirror slap (causes motion blur)
• Shooting speed (no need to move the mirror).

Once EVFs match the resolution and refresh rate reaches the level where it is not noticeable is reduced the advantage of SLR systems slips away rapidly. Currently phase detect AF is superior to contrast detect for locking onto and tacking moving targets, but CD AF is getting better and manufacturers are working on including PD sensors in the main pixel array.

Answered by Matt Grum

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Are mirror-less cameras good enough to buy instead of a DSLR for home/amateur use?

Question

I'm an amateur photographer looking to buy a camera for my home use. I called myself "photographer" just because I actually can press the button and take a photo! My first digital camera was VGA resolution (640×480px) and didn't even have a display (!), and after that I just used my phone as my camera.

Anyway, when I compare photos that taken with a professional camera (DSLR) and point-and-shoots, I can see that the difference is huge in terms of quality! Even DSLR cameras with fewer megapixels give better pictures than a higher-megapixel point-and-shoot.

I was considering the Canon Rebel T3 (18MP) DSLR, but when my wife saw that in Best Buy, she was scared of the amount of buttons and options on it. She said we need to take some classes to use it! I know this camera should have an "auto" mode that would be easy to use, but she still didn't like the camera and was scared of not being able to use it.

Then I researched around, and found "mirrorless" cameras interesting because they have DSLR quality in point-and-shoot form factor. But they seem to be "beta versions" of a concept. Most of them don't have flash or microphone, and are very expensive. I liked the Sony NEX-5 but as I said, the camera does not seem perfect.

Are the mirrorless cameras are limited by their nature, and we can't have all DSLR features in a small camera, or we will see some models that are perfect?

Answer

Those cameras are only limited by the fact that they lack a reflex mirror to form an image through an optical viewfinder. By the same token, DSLRs are limited by the fact they need a reflex mirror in the optical path.

What does that mean?

• In terms of image quality, nothing. There are currently mirrorless cameras using the same sensors as DSLR. Even those with slightly smaller sensors (all except the Pentax Q) are not far behind.
• In terms of speed, not much. Current DSLRs are faster than mirrorless cameras at autofocus because they use Phase-Detection rather than Contrast-Detection. This is not an an intrinsic characteristic, as phase-detect can be implemented on the sensor (as in the Fuji F300 EXR) or in the optical path using a semi-transparent mirror (as in the Sony Alpha SLT-A55). Other aspects of speed such as shutter-lag, continuous drive are very similar.
• In terms of versatility, mirrorless cameras have more potential. The shorter flange-distance lets mirrorless cameras use more types of lenses via adapters than any other type of camera. One neat trick is that you can buy a tilt-shift adapter that adds that capability to a DSLR lens when mounted on a mirrorless camera.
• Mirrorless cameras are presently limited. They key is presently. They are limited in number of native lenses which are relatively new compared to DSLR lenses. They are also limited in functionality because there are not that many models. For example, there are no weather-sealed mirror-less cameras and there are none with a built-in GPS.
• In terms of size, mirrorless cameras are smaller and lighter. This is an intrinsic advantage of the form-factor. Even those with a built-in EVF can be made very compact.

Mirrorless cameras also have advantages for video as they can be used at eye-level with a built-in or optional EVF. You are right that a few models do not have a built-in flash but some DSLRs don't either. Those particular models are trying to show how small a mirrorless camera can be, but that does not mean you have to buy the smallest. A Panasonic GH2 for example is reasonably ergonomic and quite full-featured.

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What does the acronym SLD stand for?

Question

In this answer a reference was made to SLD cameras, also "called Mirrorless Interchangeable Lens Cameras". I realise that this is a synonym for "EVIL" cameras such as the micro-Four-Thirds cameras and the Sony NEX. But what does the acronym stand for?

Answer

Single Lens Digital (more on wikipedia). It doesn't really make sense in the context of EVIL cameras, since these cameras have interchangeable lenses.

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