SLR Live View

Digital Single Lens Reflex (SLR) – Live View

Written by: Siegfried Seierlein
Last Updated: 22th May 2008

What is Live View?

The ability to see the picture you about to take on the camera screen is called Live View. One of the most practical aspects of the compact camera is the ability to see how the picture will look like prior to pressing the shutter all the way. Many modern compact cameras do not even have an optical view finder. The “traditional” SLR camera on the other hand does not have this ability to see the target picture on the screen. It is this ability to view the picture live on the camera screen that makes the Live View function so interesting for the SLR photographer and such a powerful functionality for the compact owner.

Yes one can argue, what is so great about the ability to see the picture prior to pressing the shutter all the way? Apart from the obvious advantages, it is the ability to see the effects of different exposure settings or the effect a change in white balance will have before taking the picture that makes live view a must have function. Live view could typically include a live histogram on the live view screen while framing the picture.

Before the event of live view and in contrast to the compact camera the SLR user could only look at the picture after it was taken. The only way of framing a picture with a SLR without live view is to view the picture through the optical view finder. With almost all SLR cameras without live view it is for example not possible to see the effect of depth of field in the OVF. Its only possible to see the optical effects of different aperture settings when a special button is pressed.

A list of typical advantages Live View on the SLR can offer the user can be as follow:

The ability to frame the picture while seeing it on the camera screen. (100% view is optimum)
The ability to have different types of framing guidelines on the screen.
The ability to have face recognition on a digital SLR. (Typical compact camera type function)
The ability to see the effects of adjustments made to exposure, prior to taking the picture.
The ability to see the effects adjustments on white balance will have to the picture.
The ability to have a live histogram of the picture that’s about to be taken, on the screen.
The ability to benefit from the superior focus speed of a SLR while in live view.
The ability to see real depth of field variations on the live view screen.
The ability to do accurately manual focus while seeing the picture live on the screen - for example in macro
I will not be surprised to see video clip recording in the near future.




		Typical view scene seen through the SLR View Finder




		Live View picture seen on the SLR screen

Short history of Live View and SLR cameras

In 2006 Olympus was the first manufacturer to launch a SLR with the type of Live View we see in SLR cameras today. Looking back it is easy to ask, but why did somebody not do this earlier? Its only when you take a closer look at what Olympus had to do that you start to appreciate just how significant this first “real” live view SLR was. I understand that their has been other manufacturers that did make use of the benefits live view could offer but they did not implement the “complete” offer like Olympus did with the E-330. I decided not to go into to much details on all the different efforts made to use selected advantages “live view” offered in the early days. I decided to rather focus on those products that I believe really set the pace and the standards in terms of the current trend in live view SLR products.

Olympus who traditionally used CCD type sensors supplied by Kodak, were known for their unique picture qualities. It was generally believed that the unique “Olympus” trademark picture quality was the result of the famous Kodak sensor. To implement the first live view, Olympus had to move away from the Kodak sensor and they had to use a new developed CMOS type sensor. In addition to the new sensor, Olympus had to also design a new optical view finder arrangement (Optical Porro Finder) that could feed the picture signal to the main camera sensor and to a special live view CCD type sensor. The following is a extract from the Olympus web site describing this excellent new sensor:

“High image quality with a dynamic range of gradations has been achieved.”

The E-330 boasts a new image sensor that operates with lower power consumption, while maintaining superior image quality through its high-resolution, full-frame CCD. Compared to the conventional CMOS sensor, the optical aspect ratio produced by the Live MOS sensor in each pixel is larger, so photographic expression in more subtle tonal gradations is enabled, from the highlights to the shadows, and noise reduction has been enhanced. In addition, blue color reproducibility and the separation characteristics of the reds and greens have been greatly expanded. The vivid blues of the sky, the greens of foliage, and skin tones are accurately reproduced.

The new Live MOS Sensor achieves greater noise reduction thanks to 5 V-driven processing technology. Greater resistance to noise generated on the surface of the PC board is also made possible by embedding the photo diode deep in the silicone substrate. The loss of pixels that occurs when shooting in the dark results in white dots or graininess is effectively suppressed, ensuring that the clearest possible images are captured”

What added to this extraordinary design was another first in a SLR namely a tilt screen. Never before did any other manufacturer consider a movable screen.

Why would anybody need one if the only function was to view the picture after it was taken.

Olympus with a all new concept saw the value of having a tilt screen and to really complete the full advantage of having live view they added the tilt screen.

I am lucky to own one of these great pioneering cameras and its really true, the sensor plus the sum of its other parts is a ongoing discovery and joy.

Interesting was how Olympus implemented the live view functionality using a Mode A and a Mode B. Mode A used a separate CCD type sensor to convert the signal coming through the lens and to display the signal on the live view screen. The advantage of mode A was that the main mirror did not move during the live view mode and the E-330 had therefor the full functionality of its fast phase detect auto focus sensor. The disadvantage with the then mode A is that the signal reaching the live view CCD was only approximately 90% of the full signal strength plus the live view CCD had only 92% of the full view. That resulted in a “dark” type of “small” live view picture.

Important to take note of at this point is the fast phase detect auto focus sensor. These sensors are build in below the main mirror and if you have a close look on the main mirror of your SLR camera then you will see the camera focus pattern on the main mirror. This pattern allows for the signal to go through the mirror and to fall onto the auto focus sensor. If the mirror is moved away from its normal position then the signal will not reach the auto focus sensor.

To fix the smaller and the under exposed picture in mode A, Olympus created a more accurate “picture” Mode B. With mode B the main mirror will flip out the way to have the picture signal hitting directly onto the main image sensor. The main image sensor then produced the live picture on the screen. The disadvantage of moving the main mirror out the way is that the fast phase detect auto focus sensor then does not get a signal. During the first few months of the E-330 live cycle the E-330 could not perform an auto focus in mode B and the only way to focus was for the photographer to use manual focus. A few months later Olympus offered a firmware update that enabled the E-330 to activate the fast SLR type phase detect auto focus sensor by dropping the mirror back into position, to focus and to again swing the main mirror out the way to activate live view. To activate this mirror down, focus, mirror up process the photographer has to press the AFL/AEL button on the back of the E-330. Important to note is that the E-330 could not focus in Mode B (like the newer E-410) by pressing the shutter all the way, the E-330 could only do that in Macro mode.

Folks I spend a lot of time to describe the E-330 and as you will see from the rest of this article it was important to do so because the E-330 in many aspects defined the future of live view and most modern live view cameras has the trademarks of the E-330 in their D&A


		Even though a great design the E-330 did have major weaknesses. The reason I say the E-330 was limited in its application of the then live view function is for the following reasons. In Mode A the separate live view CCD sensor only displayed 92% of the full view plus it did not receive the full exposure from the lens. The reason is that the signal was fed through a 2nd “split“ type mirror to the live view CCD sensor. The full signal strength did therefor not reach the CCD sensor and when looking at the live view screen in Mode A one often notice that the live view is not at the right “exposure” It was therefor difficult to really frame a picture because one did not have the full view plus in poorly lid areas the live view lost much picture detail.

			Mode A




			Mode B

		In Mode B the E-330 use the main camera image CMOS sensor. This resulted in a full view plus better exposure characteristics. The disadvantage of the then live view as in the E-330 is that in none of mode A or B it was possible to see the effects of what exposure adjustments or white balance adjustments will do to the picture. The view reacts similar to what the E-410 will do when in live boost mode. Contrary to popular believe, the E-330 made huge steps towards a perfect live view but at the end the picture on the screen had only a basic implementation of the current functionality one see with live view cameras. Therefor the only advantage the E-330 offered was the camera’s fast phase detect auto focus in live mode A, and the opportunity to frame the picture in live view, whether it was for a landscape picture or a macro picture. The ability to have the camera at different angles because of LV and the tilt screen was also a great idea.

The current or the newer generation of Live View cameras.

Like I said in the beginning of this article I will spend a little more time on the E-330 as it was a pioneering product in terms of live view but it also had major weaknesses. It is these weaknesses that should become your benchmark I believe when evaluating a new SLR camera. Allow me to give you a brief description of what I believe you need to carefully evaluate:

Its good to have live view but as you will learn in the next paragraphs, what it really offer the photographer as another “tool” to set up and to evaluate and to make decisions on exposure and white balance is what will really set the benchmark products apart from the average products. The live view screen should offer a live histogram, it should offer a true reflection of what changes in exposure does to the live picture plus it should assist the photographer to set white balance while evaluating the changes on the screen. If this is not the case then live view will only offer a limited “live view on the picture” type advantage.


	I am happy with my E-410 and the older E-330. The L10 from Panasonic is a lovely camera and its like a dream camera for me, the Oly 4:3 standard, the Leica glass and the photographers feel to it.

In 2007 Olympus launched a much more improved Live View (LV) with the E-410 and the E-510. The reason I say much improved is because with the E-410 and the E-510 Olympus added the discussed “benchmark” functionality. These two cameras offered the older type “Mode B” live view plus the added ability to see the live histogram plus other similar functions. In addition it is now possible to focus when taking the picture. To do this the E-410/510 will drop the main mirror to activate the auto focus sensor, they will then focus and then they will take the picture. This is a slow process that goes with a clak clak of the mirror.

In 2008 a host of new SLR cameras were launched with live view. The following SLR’s are now equipped with live view, Olympus, Canon, Sony, Nikon and Panasonic. While collecting information for this article I went to a large store that has powered cameras and that will allow photographers to use the cameras in the shop. I tried the Panasonic, the new E-420, the Canon 450D and the Sony Alpha 350. My son has the 40D from Canon and with small differences the E-410/E-510 and the 40D has a very similar type live view functionality. In the first version of this article I wrote:- “In my opinion, Sony has the most advanced implementation of live view to date and Sony theoretically can do all the above live view characteristics.” I decided to leave this statement as is because after handling the different cameras, this was the impression I left with for home.

There are also a number of unique differences between the different manufacturers and the way live view is implemented. I know the Olympus E-410 well and also the E-330. The E-420, the Panasonic, the 450D and the Sony I tried in the store and have a fair understanding of each of their functionality.

This is a lovely picture showing how the signal is reaching the sensor when the shutter is opened.

The diameter of the shutter can be changed and that then represent a aperture value.

The 2 main auto focus technologies, Contrast or Phase detection focus.

To better understand the different live view technologies its important to briefly look at how digital cameras achieve the correct focus. There are mainly two types of technologies used in digital cameras.

The first is the so called Contrast Detection and is used in compact cameras. The main picture sensor is used to detect the biggest contrast in a picture and based on the contrast, the camera will adjust the focus automatically.

The new SLR camera from Panasonic and the new E-420 and the E-520 from Olympus and the new 450D from Canon use their main picture sensors to do the above mentioned contrast detect auto focus.

On the left is the screen of the new L10 SLR from Panasonic. It uses the main sensor to create the live view.

One can select different guides or grid lines to help the photographer to frame the picture, similar to a compact camera.

On the picture to the right one can see how the focus blocks is identical to a typical compact camera. Up to nine such auto focus frames are available on the new L10.

The disadvantage of the compact camera contrast type auto focus is that it is slow plus one could have poor focus abilities in poor light.

The second type Auto Focus is Phase detection Auto Focus. This is an advanced and a dedicated auto focus sensor in SLR type cameras. The main mirror has less silver in selected areas allowing the signal to pass through onto the dedicated phase detection auto focus sensor. These auto focus sensors are generally super fast and very accurate.

The challenge with live view is to keep the main mirror in place. That ensures that the SLR type phase detect special sensor stays active. The moment the mirror is moved out the way like in the E-410 or the E-510 then the auto focus sensor becomes inactive.

The new Sony and the older E-330 are the only cameras that each have a clever design to keep the phase detect sensor active during live view. Both keep the main mirror in place during live view. Sony and the older E-330 use different methods of “exposing” a special dedicated live view CCD sensor. Sony currently use a better design and therefor has more signal on the live view sensor and therefor the better quality (brighter) live view of the two.




		Here one can clearly see the clever way Sony has implemented live view. A number of things happen when live view is selected. First a cover is moved in front of the view finder to prevent any stray light from entering the sensor area of the camera. Secondly the top mirror is tilted slightly so that the signal is aimed at the Live View CCD sensor. The main mirror stays in place and that enables the advanced SLR phase detect auto focus sensor to stay active. Its when one see the Sony live that one appreciate the brightness of the live view screen versus the E-330 plus the additional picture information in the LV screen. What was also fascinating for me was the way one could see the SLR type focus points on the live view screen. On the below left picture live view is not active and the picture to the right is with live active. In the above picture one can see that the main mirror stays in place in both live view and normal mode. That means the focus sensor always stay in place. The clever way Sony implemented the new live view in their Alpha 350 explains why reviewers are getting so excited with the Sony version.



	Short summary of modern or current SLR cameras.

The current generation of live view DSLR cameras showed a few interesting trends. For this discussion I like to include the E-410 and the E-510 from Olympus. Olympus who was the first to launch a “complete” live view camera in 2006 decided to follow up with two new live view models in 2007. Based on their experience with the E-330 they decided to launch a SLR type Live View E-410/E-510 camera, something that could help the true SLR user to use his or hers camera better. The press was not happy as they got use to the idea of having live view and they were looking for the Compact type Live View.....everything should function that way, they demanded...

What is the difference between SLR type Live View and Compact type Live View?

With SLR type live view the photographer will use the live view to check focus, framing, histogram, exposure or white balance settings on a live view screen. To do this the mirror will swing out the way and the main sensor will be used to “see” the picture, old Mode B. By swinging the mirror out the way the advanced SLR auto focus sensor will not receive a signal and therefor the live view will not function like a compact camera type live view. When done setting up and checking the picture, the framing and exposure settings, then the camera will be switched back to normal mode and the SLR will be used like a normal SLR to focus and to take the picture. Live view in this example becomes another “tool” to the photographer to better set up the picture before taking the picture.

With Compact type Live View the SLR behaves like a real compact camera, a sort off old mode A. This includes a live view screen, contrast detect type auto focus with newer models, phase detect with the E-330 and Sony, face recognition and the ability to see the histogram, exposure and changes to the white balance. Similar to the SLR type live view but the main difference is that the SLR will also be able to focus and to take the picture while in live view. In this case the camera use the main sensor to perform the auto focus like with a compact camera, except the E-330 and the Sony. In this case live view is not only a tool but it also acts like a normal compact type camera when in live view.

The SLR type live view does not work in the similar way. To focus first the main mirror has to swing back into position and then the focus sensor will receive the signal and then the camera can focus. This is a slow and sometimes irritating process. Personally I rather use this type live view as a “tool” to set up my picture, switch back to normal mode and then use the SLR like a normal SLR. This is why I call this type of operation the SLR type live view.

Interesting is to look at 2007 when the E-410 and the E510 was launched. At the time the new Panasonic SLR was also launched with a SLR type live view. Shortly after its launch Panasonic decided to go for the compact type live view and the L10 became available with the compact type live view. Panasonic therefore was the first to introduce face recognition in a SLR camera.

Olympus with their recent experience with the E-330 decided to keep the SLR type live view. One cannot help to ask, was it not possible to use the E-410 and E-510 main sensor as a contrast detect focus sensor like is now done with the new E-420 and the E-520.

In 2008 a very interesting thing happened. To date it was generally accepted that their will be two types of live view, the old Mode A and the Mode B of the E-330 from Olympus. Mode A or the Compact Live View is possible using either the main image sensor or a separately installed CCD sensor. With the main image sensor solution the camera will use contrast type auto focus and with the separate CCD type sensor the camera (Sony) will use the fast SLR phase detect auto focus. Mode B or the SLR type live view is as discussed with the E-410/E510.

Then Sony surprised everyone with their really extraordinary solution. Sony was the first manufacturer that were able to bring Mode A and Mode B very close to one solution. For the first time the SLR could be used like thoroughbred SLR while in live view mode A. The reason is that for the first time the advanced SLR phase detection auto focus sensor was now being used, like in the E-330 in Mode A, but different to the E-330 the live view CCD received a nearly full strength signal when in live view plus it has the other benchmark type functions. The one surprise with the Sony live view solution is that the live view is only 90% of the full picture view. The Sony does however offer all the other benchmark type functions discussed above. In addition Sony also offer a few unique functions in live view that could appeal to the user.

The reason Olympus had to develop Mode B was to cater for the signal lost to the live view CCD. Mode B reads the picture directly from the main image sensor and that has a much better view of the image. Sony does not need Mode B because they have a excellent quality signal reaching the live view CCD.

Olympus decided to implement a similar technology like Panasonic and the E-420 and the E-520 now has the compact type live view. The E-420 has three modes and like the old E-330 it enables the photographer to select the compact type live view or the SLR type live view. The E-420 also allow a hybrid setting. I have not seen any information on the E-520. The Olympus E-420/E-520 could become more popular than the new Alpha 350 from Sony because the E-420/E520 offer a 100% view with its compact camera option live view. In addition 14MP is nice to have but when the pictures are saved on hard disk then one needs space!!

Somebody asked me to include the Nikon Live view products in the article.

Must say, Nikon makes a good impression when you visit their site. For example on the D3 site Nikon discuss how the D3 handles DR, makes you think...

On their site Nikon mentions that the D300 can do both phase detect and contrast auto focus. Nikon calls it tripod and hand held mode. See the D3 description for more details.

The D3 offers the same tripod and hand held live view modes than the D300.

The tripod mode uses phase detect or the compact camera type live view and the hand held will keep the phase detect auto focus active and I assume the Nikon will then switch to the SLR type live view.

Nikon does not give much info on their site on live view and its clear that live view is not one of their main discussions points.

While on the Nikon site I saw that Nikon has received a few prestigious prices.

If I am ever in the market for a D300 type camera, well I like the color of the Nikon and I think the Tripod mode Live View is cool..

Interesting is that Canon now also offer live view on the 40D, the 450D and the 1D. The 40D has the SLR type live view implemented and it works like a dream for the advanced SLR user. The high speed and the unique control Canon as over the mirror makes for a excellent implementation of the SLR type live view. Interesting is that the average reviewer is asking for compact type live view and has therefore expressed dissatisfaction with the way it’s done in the 40D. The typical advantages one expect of live view is wonderfully implemented with the 40D.

With the 450D Canon did something similar to Olympus. Canon implemented the compact type live view using the main sensor to display the picture on the screen plus they use the main sensor to focus. In a second mode the 450D can be used with SLR type live view similar to the 40D.

On the 1D Canon also offer a live view option. Not much information is given on the web other than the camera specification. I decided to not further investigate as personally I do not think I will ever use the 1D and I will be honored if a reader would be interested. If you have some interesting information on the 1D, please pass it on and I will be happy to add it.

Conclusion

Personally I think we only at the beginning of what live view will bring to the SLR world. Interesting is that many forum participants always speculated and said high end compacts like the G9 could take away sales from the SLR market. Personally I think the reverse is possible today and for the manufacturers to protect the high end compact market they will have to do some serious thinking.

Live view potentially have the ability to become the next noise or dynamic range discussion in the industry. My advice will be to understand the basic technologies used and not to get caught up in reviewers talk about the technology. I already enjoy the wounds of what can happen on forums. I have found a fair amount of information on the web and if you really interested then its possible to build a interesting comparison table to help you decide.

I like to conclude with one last discussion. Often we read that the E-410 or the E-510 or the 40D has a sub standard type live view. I think it depends on the way you look at it. If you understand and if you keep in mind that the live view in these cameras are the SLR type Live View and that its added to the camera as another “tool” to help the photographer, then one realize what a great help it is in these cameras. If you want to use any of these cameras like a compact camera in live view mode, then you will be disappointed.

We live in exciting SLR times, I hope you enjoyed the article as much I did writing it. This and my other articles are written to help photographers to better understand photography and their hobby.

Kind Regards

Siegfried.