What are the advantages and disadvantages of an electronic viewfinder vs. a DSLR's optical finder?

Question

DSLR cameras, like traditional film SLRs, have a viewfinder you put to your eye to look through the lens.

These days, many mirrorless cameras are styled just like DSLRs but use an electronic viewfinder.

Since both exist in the market at the same time, clearly there's advantages and disadvantages to both. What are they? In what situations might one prefer one to the other?

Answer 1

Electronic viewfinder Pros:

• Potentially smaller and lighter camera bodies and lenses (particularly wide angle lenses)
• Can zoom in to verify precise focus and depth of field
• Can see (almost) exactly what the camera sees, even in low light
• Can superimpose more complex data over the image (e.g. zebra stripes, focus peaking); see note below.
• No mirror assembly to fail
• Quieter shooting (no mirror motion)

Electronic viewfinder cons:

• Uses significantly more battery power
• Lower resolution when not zoomed in (harder to judge focus by eye)
• Temporarily obliterates night vision when used in the dark, making it hard to get around
• Slight latency (worse on older gear)
• Unless combined with electronic front curtain, significantly longer shutter lag (because it starts out open)
• For cameras without a fully enclosed viewfinder, light from screen can annoy others
• For cameras without dual-pixel autofocus or dedicated focus pixels, significantly less reliable focusing

Note that it is possible to overlay some data over optical viewfinders, of course, such as focus point dots, boundaries of focus zones, and so on. However, transmissive LCDs are much more limited in terms of what can be superimposed practically, because they can basically only darken, not lighten the image.

Eventually, when transparent OLEDs make their way into DSLRs, this difference will go away, but as far as I know, they have not appeared in any DSLRs yet.

Answer 2

EVFs generally have the advantage that they let you see what the camera is going to see when you take the photograph, and in particular you can look through an EVF with the lens stopped down, so you will see the depth of field that will be in the picture. OVFs on DSLRs really only work with the lens wide open (you can often stop the lens down, but then the OVF is unusably dark for general use), or on rangefinder-style cameras they go to the other extreme: there's huge DoF in the OVF and you have to know what the lens will see.

Older EVFs were laggy and not really very high resolution: I think that newer EVFs are much better in this regard.

A significant advantage of an OVF is that you can see through it it with the camera off. That means that you can just put the camera to your eye to frame a picture or decide if there is a picture worth having and it's there instantly: you don't have to keep the camera awake to use the OVF. That means you get much better battery life as you can let the camera go to sleep, and you can also be framing the picture while the camera wakes up.

Answer 3

An optical viewfinder can never have any lag, since it's optical it operates at the speed of light. On the other hand with an optical viewfinder you will not see exactly what you will get in you image file. Exposure, white balance, color and image crop (3:2, 1:1, ...) settings are not visible in the optical viewfinder, but can be visible in the electronic viewfinder (depending on camera model). Also, a electronic viewfinder can display manual focusing aids. The optical viewfinder of a DSLR has a short blackout when the mirror moves. A electronic viewfinder don't necessarily have this blackout.

You can get all of the benefits of the electronic viewfinder on a camera with optical viewfinder using the back screen, which consumes even more power and is hard to view in bright conditions.

Preference for electronic viewfinder:

• When a smaller camera is required
• Flash photography
• Photographing in low light situations
• Fast action (if there is not blackout)

Preference for optical viewfinder:

• Fast action (because there is no lag)
• When long battery life is required

I personally switched to a camera with electronic viewfinder about 2 years ago, after using SLR and DSLR for approx. 10 years, because of the smaller size and weight.

Answer 4

Manual focusing needs to be handled differently with an EVF. Since most EVF are much lower in resolution than the sensor, it is hard to judge best focus by sight, requiring the use of focusing aids like peaking or focus magnification. On the other hand, when these aids are used (which might require additional operating steps), manual focus will often be easier.

A special case where EVFs can become very inconvenient to use is when there are extremely fast moving elements in the frame. Examples: Photographing far away subjects right out of an express train (while there is track-side junk in the lower part of the frame and/or occasionally passing through your view), manually focusing a very long lens that is only weakly supported... These can result in very confusing artifacts (choppy/jumpy display instead of smooth motion blur, or much increased visual hindrance) in the EVF, or even overwhelm the EVF system resulting in additional lag.

One distinct advantage of most every EVF compared to most non-professional grade DSLRs is that you get exact and 100% coverage (with no possibility of hidden misalignment), allowing tight and precise framing.

Answer 5

There is yet another problem of mirroless - higher temperature. While sensor and processor is running all the time, big amount of heat is released and must be cooled. This may cause a lower electronics lifetime and an increase of sensor noise. So image quality can be worse if camera is longer time on. In case of DSLR it's way more simple while sensor works only in moment picture is taken.