What is an EVF?

EVF = Electronic View Finder.

Be ready to see this term used more and more, even for SLR cameras. Many a compact point-and-shoot photo camera already is equipped with an EVF, but it is most common in video cameras (and it has been for many years already). In the viewfinder, instead of looking at an image coming from a more or less complex optical system, your eye is pointed at a small LCD screen (or TFT, or OLED or whatever similar technology) reproducing the picture recorded by the CMOS imaging sensor of the camera.

After all, this is only what we already know well as the LiveView mode on the back LCD of nearly all the compact photo cameras (and many SLR too). But as a small picture in the viewfinder.

An LCD display + a viewing lens = an EVF.

In some case, you could add a small mirror for space reasons, but this is a minor variation to the original tune.

EVF and Single Lens Reflex (SLR) cameras

A Single Lens Reflex (SLR) photo camera is organized around a very mature technology in which a mirror reflects the image through an eyepiece via a pentaprism (or a penta-mirror) as in the drawing on the left.

Of course, as the film (film plane and focal plane shutter) is hidden by the mirror, this one must be drawn up to take the snapshot.

All this is greatly simplified when there is an electronic viewfinder.

Advantages and drawbacks

Advantages et gains from an electronic viewfinder

The first positive side is mechanical and optical: If you remove the mirror and the pentaprism, the architecture of the camera will be greatly streamlined, lightened and its manufacturing cost will go down. For three different reasons (at least):

• reduction of the number of parts
• reduction of the assembly complexity (or of the amount of human work needed)
• increased ease of calibration (alignment) of the optical parts (an LCD and an eyepiece, rather than a whole bunch of parts)

Even better, the disappearance of a huge articulated and mobile mechanical system brings several positive effects:

• increase of the continuous shooting speed/cadence (there’s so much less hardware to move around for a photo)
• reduction of shutter noise (in a traditional SLR camera, most of the noise actually comes from the mirror up-swing and the shutter operation; It’s worth removing one of them)
• a lighter mechanical structure through reduction of the quantity of parts and since the enclosure is lighter because it has less stress to sustain in all these shocks and moves

Also, the electronic viewfinder exactly reproduces what the sensor sees. A 100% optical coverage on a viewfinder of fully optical design has always been reserved to the most expensive SLR cameras. But when you get an EVF, 100% coverage is totally natural and effortless. Luxury comes to you in the clothes (and price) of entry level.

Then, having an LCD display brings the additional possibility of adding all the data you can think of. Many brands already experimented with this and brought us some Electronic Viewfinders with features like:

• Histogram
• Artificial Horizon
• Zoom on a part of the image
• Telltales and technical displays (aperture, speed, ISO, etc.)
• Active AF zones (including face detection)

As a matter of fact, there is no other limit than what a computer screen can display: Data, image, etc. It’s only a choice from the designer.

And it’s not even the end of it. The EVF also has a major advantage when light is low: As far as the sensor can see something, it’s only a matter of amplifying light signal (like for the ISO sensitivity selection) to make the picture readable. If the photo is possible (even barely possible), showing it is possible. Think about it! A nikon D3s digital sensor could display what it sees even in the darkest dawn it can manage. Since the digital noise is only a marginal issue on an LCD display (even at 3MP resolution), you can see what the sensor will be able to grab even in a room too dark for comfortable framing with an optical viewfinder.

If you compare it with the lowest-priced optical viewfinders of entry-level SLR cameras, the EVF is an easy winner in those low-light conditions: These simple viewfinders where already unpleasant and dark, the EVF bring a new life to cameras used indoors.

Drawbacks and limitations of the electronic viewfinder

But all is not pink and shiny. EVF have the same problems as most point-and-shoot cameras find on the rear-side LCD displays used for LiveView.

To start with, even if the electronic viewfinder (EVF) is intrinsically better protected against sunlight, it is still very sensitive to bright light issues. If there was only one thing that the EVF-sensor pair does not like, this would be high lights and bright sun (sic!) highlights are easily washed white and overblown. You will find more white flat areas than nice clear zones. The worst comes when you add high contrast to the picture. The EVF has a very small dynamic range (this is not HDR!) and the designer must choose between high-lights and dark areas.

We tend to forget it, but the human eye is amazingly sensitive and adaptable. Behind a prism and a mirror, in the brightest mid-day sun light, it can marvelously adapt to over-exposure situations that totally saturate the purely digital EVF system.

Best (or worse), the eye is extraordinarily able to switch within a few hundredth of seconds from the darkest night to the most violent lighting without even thinking about the marvelous brain processes involved. On the contrary, the EVF system uses a gain correction which will change at any time the apparent brightness to track the actual scene brightness. What is clearly an advantage in a dark room, forces the system to include an auto-adaptation feature which will change the brightness of the EVF several times per second. According to what you point the camera to, the electronic viewfinder will change from lighter to darker display. Not really a problem, but this asks for some tolerance to a process which is not natural to our human eyes. You have to get used to it.

Additionally, but this is all very sensitive to the user (you!), watching a computer screen may be more or less comfortable in the long run. As a matter of fact, if you use the EVF for long hours (this is the case for the professional photographer waiting in front of the Cannes Festival stairs, for the photo safari amateur or for the intensive tourist photographer willing to bring everything on a memory card – don’t laugh, I’m sure you shoot it as much as I do), you may come back with a serious headache. This is certainly not an issue for everybody (and you’re not supposed to keep the camera to your eye if you want to immerse yourself in your subject), but this may become a real limitation to some people. At the strict minimum, you must take very seriously the setting up of the dioptric correction of the eyepiece (much more seriously than on your current camera) to limit the impact to a tolerable level. Unfortunately, the eye seems to get more prone to this issue when the photographers gets older… Our eyes are not equal in front of photo gear. Too bad, but true.

Last but not least, even if the electronic viewfinders improve in time (and Sony has shaken the market with a 2.3-million-pixel EVF in the Sony SLT-A65 and in the Sony SLT-A77 which has raised the bar to a whole new level for all the competition), the fine quality of a focusing screen in a common optical viewfinder stays incomparably better than what the best EVF can display today. Far better! This is the reason why they generally include an additional Zoom feature allowing to better judge focus through enlarging an area (On the opposite, a company like Zacuto proposes an enhanced edge sharpening to make the focus analysis easier or more natural).

If you let your camera focus for you, honestly, you shouldn’t care much about this. If you like to fine-focus your pictures (all the more if you use a USM, SSM or similar lens which allows easy manual focus correction), if you use wide-aperture lenses (which call for a very attentive selection of the focus location or AF area), you will be in a living hell playing with buttons to merely focus while you were used to just looking at the image in your old optical viewfinder. Interestingly, Sony keeping in its technological portfolio the marvelous AcuteMate focusing glass surface (bought from Minolta and still widely considered as the absolute best here), is the first to jump to the next technology.

While we talking about AF, we must stop and remind ourselves that the disappearance of the reflex mirror means that focusing is now done from the data directly available on the image sensor. Where the traditional SLR camera focuses just before the exposure, using phase difference sensors (high precision, high speed, and not very complicated), the EVF viewfinder seems to enforce the use of automatic focusing using the measurement of a contrast difference directly on the image (very consuming in terms of processor power, intrinsically less reactive). Sony, once again at the forefront, chose to insert a semi-transparent mirror to keep the fast phase detection sensors. But they are quite alone in this decision – for now.

(Temporary?) conclusion

The electronic viewfinder is no panacea. But it brings good answers to tough questions asked by the old reflex technology, starting with price reduction for the digital photo cameras which is always a major issue for the manufacturers.

The camera owners already used to the optical viewfinder of entry-level cameras will immediately recognize the many advantages and all the more if they are occasional photographers or if they come from the compact point-and-shoot camera world.

Expert users (not even pros) will certainly have more mixed feelings, even if the most advanced electronic viewfinders like the recent Sony ones progressed in great strides. As I read in one of the recent articles about these new photo cameras, Sony brought enormous (not incremental) progress but this is still an electronic viewfinder. Not perfect, but with enough advantages to balance the drawbacks.

Now, you may have to read the post again to choose which ones are the most important for you. But there is a big problem left: We usually choose our photo camera inside a relatively dark shop (perfect, ideal conditions to demonstrate an EVF) and we use it mostly during our Summer holidays (the worst conditions to use an EVF). Some people may be unpleasantly surprised if they do not think twice before choosing a camera.

• Translucent mirror
• 36.9 Megapixel 3MOS Exmor sensor
• (No Bayer filter)
• ISO 100-102400 extendable to 204800 and 409600
• 12 frames per second
• No infrared or anti-alias filters
• Digital infrared filtering with three modes NO IR,WITH IR,ONLY IR
• In camera moire remove
• 89 cross-type points AF
• Metering direct from sensor
• 60/1-1/24000sec, time, bulb shutter (focal plane)
• Flash synchronization up to 1/500sec and high-speed sync up to 1/24000sec
• Built-In GPS and Wi-Fi plus Thunderbolt
• Two CompactFlash card slots
• Price around €3000

The author did not even take time to copy this information to their other web site SonyAlphaRumors.com ; It says it all…

Sony made several “end of life” announcements for the Alpha series of DSLR.

• Two entry-level, the Alpha 290 and Alpha 390 are clearly replaced with the Alpha 35 and Alpha 55.
• The Alpha 850 is leaving the shelves -as it was expected from a long time- with a progressive price reduction of the Sony Alpha 900 which is currently the last Full Frame DSLR at Sony. However, it is clear -if not official- that the A900 will be replaced with two new FF DLSR cameras in 2012, both of which will have semi-transparent mirror technology, like all the most recent Sony Alpha DSLR: Sony Alpha SLT-A99 and Sony Alpha SLT-A95.

• All APS-C SLR cameras
• All Full Frame SLR cameras

Gee! This is going to influence the future of the Sony Alpha line.

In a nearly parallel direction, knowing that Sony decided not to announce a new Full Frame SLR camera this year (but only in 2012), it is interesting to notice the information provided by SonyAlphaRumours and telling us that Sony determined its strategy for the year 2011. For the most significant part, Sony forecasts a complete stop of manufacturing for the Sony Alpha 850 whose stocks will plummet quickly. On the opposite, the elder brother (more endowed too) Sony Alpha 900 will see its price drop progressively at the current 850 level, to boost sales, avoid leaving too much room to the competition and empty the stocks before the arrival of an Alpha 99.

• “we’re really quite dedicated to developing products for both the A-mount system and the E-mount system because we do believe that both have roles to play” : Mark Weir clearly indicates that the NEX (E-mount) and Alpha (A-mount) ranges are not designed to compete against each other by to be complementary and to reach different targets. This is certainly not a surprise, but it’s good to hear it said clearly.
• “we absolutely understand and value the point about the continuity that an interim A700 successor model would have offered, but we prioritized the development of new capabilities, new benefits, and new technologies such that the A700 successor will be a truly unique and revolutionary product” is a key sentence where the Sony manager tells us that the spirit of continuity with the A700 does not have priority over the development of new revolutionary technologies. Who would not think about the semi-transparent mirror of the Alpha SLT (A33 and A55). This way, it is nearly completely confirmed (see more about it below), but it can also be understood as referring to many other improvements to come soon (at least, Electronic ViewFinder quality and -maybe- a record resolution for the sensor which may well be identified as a revolution).



• “everyone will realize that it was very valuable to first develop the technologies and the capabilities” has to be translated from marketese into plain English with some kind of We had too much in our hands, too much to work on, before we could build the product we wanted”. Elsewhere in the interview, it is easily understood that Sony did not want to work simultaneously on everywhere and that the A33/A55 developments must have been eating the lion’s share or the R&D resources. “We can’t do everything at the same time, so let’s spread it over time and let’s start with big-volume cameras.”
• Mark Weir also clearly state that the A700 successor will be located between the A580 and the A850. Some will want to read this truism as the hope that a traditional viewfinder will be maintained against the possible semi-transparent Pellix-type mirror and an EVF, but I believe that nothing can stop the impetus acquired by the technological transformation aforementioned. And the following phrase (“the A700 successor […] will incorporate the translucent mirror technology.“) is without any doubt: the A77 will have a semi-transparent mirror. This is now certain. Mark Weir then defends this approach by publicly stating that the associated improvements will reduce the last worries and win the last complaints back.
• Another remark about the Full Frame cameras, “the market has shifted increasingly toward the use of APS-C cameras, even in the enthusiast and semi-pro space” could well trouble those waiting for the replacement of the Alpha 850. More or less, if the market forces everybody to have high-end Full Frame photo cameras, sales go to the high-end APS-C photo cameras. We must admit that the limited success of Sony within the pro public, but it’s true that, inside Nikon or Canon, the same problem is certainly present too; with the critical difference that those two brands have a very strong presence in the pro market and probably have a slightly different perception of (and an easier path to) this constraint. As repeated by many observers, Sony still must prove worthy for pro photographers to collect the associated brand image, but the Sony Marketing is at a loss to find the means to this end. The consequence will certainly be a little less pleasant: Sony will wait more before working on an Alpha 950 (or Alpha 99) for Full Frame cameras. As everybody murmurs it, let’s not discuss this any longer before 2012.
• Some more fuzzy comments about the difficulties to ship the Alpha 580 will not shed any new light on the issue. The camera is still hard to find, but these suggest simultaneous issues of primary parts procurement and manufacturing capacity. We will probably never learn anything more precise from a Sony employee in front of a microphone.
• The zoom lenses included in camera kits are selling exceptionally well (“the 55-200mm telezoom or the 70-300mm telezoom that is promoted at the time of purchase really represents a tremendous part of the lens units that are sold.“). Nobody will be surprised by such a statement knowing that all camera manufacturers build camera kits at prices obviously attractive. But at a noticeably lower level of sales, Sony sees a real success for the 24-70mm f/2.8 and 70-200mm f/2.8 (“The other part of the business is the lenses that are sold to enthusiasts, and these are typically wide-aperture 24-70mm or wide-aperture 70-200mm“). This is recognition of the value of lenses designed and bought to be present for a long time in the expert photographer’s bag (when I was saying the same…) But Sony also makes significant efforts to present high-end prime lenses (prime = not too expensive, or 150-250€).
• “What you are seeing is the emergence of hybrid silent AF motors.” is the introduction to a list of commentaries to explain that Sony will keep on developing SSM lenses (ultrasound motor AF, expensive but very quiet) along with SAM lenses (hybrid motor AF, cheaper and somewhat quiet). the E-mount lenses are designed from inception to be silent (for video capture), but the A-mount range shall also receive more lenses designed to satisfy the video lover in Alpha suit. To my eyes, this part contains too much warm water to warrant for a clear future and the marketroid who’s talking probably translates Sony’s indecision on this issue. He even goes to the point of defending the use of external microphones…
• “there’s full aperture control with movie capture in SLT right now, it’s just not with AF at the same time.” will certainly stop most dreams short for some people still hoping to get both fast AF and free choice of lens aperture. As Mark Weir finely explains, it is mostly a matter of technical limitations and the only hope left is to give contrast-based AF enough time to improve slowly (for the time being, for technical limitation, phase detect AF can only work at wide open A-stop – or up to f/5.6).
• One short mention to confirm the 500mm G f/4.0 prime lens, without giving even a hint of a launch date.
• the end of the interview covers the evolution of the different markets and requires to be analyzed with a big grain of salt in front of the statements from the other camera manufacturers, but it can be summarized in telling that all manufacturers think that 2011 will be a good year for photography and that Sony wants it to be a good year for 3D photography (Sony decided to heavily bet on 3D in all of its markets).

As we can see, this is one of those rare interviews where a brand representative openly speaks and provides a lot of precise data without hiding it behind a heavy curtain of unreadable bad English. Congratulations to Imaging Resource which had already shown their ability to write excellent gear tests and demonstrate that they can also write other article kinds.

In any case, all bets and rumors are pointing at an announcement not before the end of 2011.

This pro-tele-prime lens announced a year ago by Sony includes a small DMF button whose meaning should be Direct Manual Focus. The use of this button would be to easily move from a “normal” AF mode to a “x15 zoom” mode allowing easier fine focusing.

This feature has nearly no use in a prime lens which certainly contains no optical element to support such a feature. AP concludes that the only explanation is that this is a control for an SLR body feature associated to the electronic viewfinder of future cameras from Sony. Good reasoning…

The consequence:If a prime lens whose price (a few thousand Euros, maybe 10000€/$10.000) puts is firmly in the pro range contains such a feature, the electronic viewfinder is coming to the next pro cameras from Sony. The conclusion is that the Sony Alpha 77 (or Alpha 750) which will follow in the steps of the Sony Alpha 700 will be equipped with an Electronic Viewfinder (EVF) and a semi-transparent mirror like the Alpha 33 and Alpha 55, that are clearly in the entry-level part of the Sony camera offering.

It’s still a bit weird for a button already appearing on the 500mm f/4 mock-ups presented a little more than a year ago. But the indication is quite parallel to the success observed by the semi-transparent mirror system with an electronic viewfinder of the SLT-A33 and SLT-A55 (big sales everywhere in the world in 2010, starting with the Japanese market).