The 20Da got me thinking...

[Chris1le]

Now that we are about to have a DSLR that can offer a live preview which would also enable the posibility of a live histogram would it be possible to use a histogram as a sort of automatic exposure control? Wouldn't it be possible for the camera to keep from clipping the highlights and shadows using the histogram? would this even be benificial? Further still, since the camera would know which areas are blown out as shown by the flashing highlights would the camera not be able to simply decrease the sensitivity to those pixels? I realize live histograms are available in some P&S cameras. I just don't know if it is for information or if the histogram can control the exposure. It will be interesting what the next few years will produce. :confused: Just some thoughts of mine. Comment if you'd like. :lol:

[kawter2]

that is basically what is allready happening with the meter

the diference is that when you look at a histogram you are looking to see if it matches what you are seeing, there is no "perfect histogram" it is always relative to your subject

[Chris1le]

I understand what is happening with the meter but a live histogram would let you know how the meter reading and the parameters you select will effect exposure before you take the pictue. Giving you the oportunity the adjut some more before taking the shot.

[hmhm]

A live histogram would have "finer granularity" than the current multi-segment AF exposure metering. The current exposure metering can certainly try to avoid blowing highlights and such, but given a finite number of segments, it necessarily averages the light that would hit an entire area of pixels.
-harry

[Jesper]

Like Kawter says, there is no single perfect histogram for all subjects. Sometimes you deliberately want your subject to be dark or light on the photo. I wouldn't want a camera that always "exposes to the right" (http://www.luminous-landscape.com/tutorials/expose-right.shtml) automatically for me. Maybe as a feature that you could switch on and off it would be interesting.

It would be really handy to have a live overexposure warning (the blinking highlights that you can see in when you review a photo on the LCD).

[Illegally_Alive]

I'm sorry to say guys but I disagree. Maybe I'm too old school, but I like my viewfinder bright and clear and for such a contraption to work would detract from that. I say leave the lcd stuff to the point and shoot's. It's next to impossible to view the lcd in day light anyway. But that's just one man's opinion.

[Anders Östberg]

I don't really like the idea of a live preview either, but maybe it depends on what and how you shoot.

For any action type photography (sports, birds, kids...) it wouldn't work very well to not have your eye in the viewfinder. Landscapes, astro, architecture... OK.

A viweing screen doesn't work very well in bright daylight.

It's next to impossible to hold a heavy camera steady any longer periods if you have to hold it out a foot or two in front of your body. A small P&S, OK, but not a dSLR with a big lens.

[BoySpot]

Someone mentioned above that you sometimes want the shot lighter or darket by choice. Don't forget, some images are just not a good spread of colors and tones. Try taking some shots of aircraft against a blue sky. The histogram will be unlike anything you normally see. This would not be a good time to have the camera changing your settings.

Also, if the pixels are toned down individually, how will you build up the necessary contracts in an image? Every pixel will be trying to set itself to the reading for a well exposed mid gray. That isn't going to work. Whilst the meter may not be as complex is a histogram (although they are pretty complex anyway), it does do a far better job of balancing across the image. After that, it is up to interpreationa nd experience to work out what you really need. You can't yet get everything in a shot irrespective of its lighting.

[ScottE]

A live display from the imaging screen could have some other uses as well. For example, if you view a live image, it would be able to build tilt, swing and shift movements into the camera to move the image sensor. That would be great for landscape and architectural photography as long as the LCD was big enough and sharp enough to be used for focusing. Using full size EF lenses on a 20D size sensor should leave lots of room for shift movements.

At present, I believe electronic viewfinders would have to be faster and have greater resolution before they could replace an optical viewfinder. Some day it will happen.

Scott

[Jesper]

I'm sorry to say guys but I disagree. Maybe I'm too old school, but I like my viewfinder bright and clear and for such a contraption to work would detract from that. I say leave the lcd stuff to the point and shoot's. It's next to impossible to view the lcd in day light anyway. But that's just one man's opinion.
The 20Da does not have a dimmer mirror / viewfinder. The mirror is flipped up (mirror lock-up) to allow live preview on the LCD. See this: http://www.photo.net/bboard/q-and-a-fetch-msg?msg_id=00BAMO

So in "normal" mode, the viewfinder should not be dimmer. However, with live preview mode, the viewfinder would be blocked by the flipped up mirror - you can't use live preview and the viewfinder at the same time.

[ijohnson]

I guess I knew this would happen one day....


I need to know the following before I could move over to this technology.

a) Large, VERY high resolution display to ensure focus accuracy.
b) A very, very fast display that has no noticeable lag and that when combined with an un-noticeable shutter lag is still unnoticeable in regards to total lag.
c) An assurance that allowing information to constantly pass through the sensor would not corrupt or degrade the desired image as an end result.
d) Another assurance that leaving the sensor exposed to light for such a long time, especially direct sunlight in either accidental or intentional circumstances, would not affect the performance of the sensor in the long run.
e) A flip out display like the one used on the g-series cameras to expand the use of the camera from certain angles.
f) 1 year of people using it and not getting pissed off, even keeping in mind that Canon is exceptionally good at doing an appropriate amount of R+D to ensure the reliablility of the product.
g) Months of brooding over the decision and reading endless posts on this forum.

Looks like 2007 for me.

I can't wait to start reading more about it.

-Isaac

[sjprg]

The main advantage to live preview as I see it is to be able to shoot tethered to your laptop. For astrophotography, or studio/location work this will fit with the new WFT-E1A
wireless transceiver just released, allowing composing and focusing to be done on the computer screen. I can see the day coming when the USM motor will be able to be controled by buttons on the computer and the firmware having a remote control mode.
This will probably happen on the 1 series first and then trickle down.

[Jon]

Going back to the original question, I doubt that a histogram, although more granular thant the existing multi-point metering system, would offer any real improvements in automatic exposure calculation. It would be more vulnerable to specular highlights, for one thing.

From Bob Atkins' writeup (see Jesper's link), I infer that you can open the shutter to focus (or compose?) via the LCD, but that the shutter will need to be closed again before you can take the picture. For astrophotography exposure times this may not matter, but for "normal" use, it would get very old very fast.

[Bodog]

One of the coolest (and most useful) features of my old Dimage 7 was the ability to press a button and get real time histogram in the viewfinder. Sure made it easy to shoot in manual mode. If Canon can do that in a DSLR...

[Chris1le]

All great comments. I wasn't really talking about the 20Da as it is right now. I was just thinking about how this and all the other little improvements in digital technology from all manufacturers will change the way the cameras of tomorrow will perform. As it is right now digital cameras try to mimic film and all the ways we used to get correct exposures. I wasn't thinking of using the histogram instead of an exposure meter more like in addition to. I just have a feeling cameras are going to start behaving differently in the not to distant future. :confused: