Highlight Blowouts

[canon shooter]

I read that some digital cameras have a light that flashes in the viewfinder if the shot is going to blowout the highlights.

Does the 20D has such a function.

[Specialhawk]

There is no way for the camera to know this in advance.

I think what you are refering to is the flashing of blown out highlights on the review LCD after you take the shot.

The only thing, i think, that flashes before a shot is the aperature number or shutter speed if the required setting is unavailible due to gear restrictions.

[Bob_A]

You can't see what will happen before the shot is taken with a DSLR. However, the 20D does have a feature where the blown highlights are shown as flashing when you view the image on the LCD screen on the back of the camera after you take the shot.

Personally I don't use the feature, and prefer to take a squint at the histogram when I'm concerned about potentially blowing the highlights.

[karusel]

There is no way for a Canon DSLR camera to know this in advance.

Fixed.

Lots of non-DSLR cameras have that, plus... I forget which DSLR, Olympus maybe? Because the light falls directly on the sensor plane and the calculation is then easy.

[Bob_A]

The olny DSLR I know of that can give a live preview is something like the Canon 20Da which is meant for astrophotography. Even then, the live preview is on the LCD screen at the back of the camera, not in the viewfinder.

[Specialhawk]

ok guys, we're all impressed with the vast knowledge of DSLR's here...but there is no way for his camera to know this.

Isn't this question answered?

[canon shooter]

Is this feature a default feature or do you have to turn it on.

[canon shooter]

You can't see what will happen before the shot is taken with a DSLR. However, the 20D does have a feature where the blown highlights are shown as flashing when you view the image on the LCD screen on the back of the camera after you take the shot.

Personally I don't use the feature, and prefer to take a squint at the histogram when I'm concerned about potentially blowing the highlights.Bob, I need to understand the histogram more. How do you tell by looking at it if the exposure was correct or not.

[Jon]

Briefly, it shouldn't be bunched up at either end (unless you're shooting a snowscape or a coal mine ;{)# ).

[Specialhawk]

Briefly, it shouldn't be bunched up at either end (unless you're shooting a snowscape or a coal mine ;{)# ).

Indeed, we could sit here and tell you what the "perfect" histogram should look like but the truth is that it depends on what the subject is. But in general, adding on to what john said, the peak should lay somewhere in the middle of the histogram typically.

***EDIT***

Also, the more you work with your camera i think you'll get a feel for what your LCD is telling you. You shouldnt base the image from the LCD on the actual image as there are too many variables but after owning the same camera for over a year and never touching the LCD brightness, in certain situations i dont even need to look at the histogram (rather i can look at the image) to tell if it's being exposed enough or not enough.

Just keep taking pics and you'll get it. In the meantime, if your subjects are stationary, it may be a good idea to bracket your photos. One or one and a half stops to the left, one in the center, then one and a half or so to the right. This will insure that out of the 3 shots one of them should be on target.

Is this feature a default feature or do you have to turn it on.

I think it is a default feature, good way to test is purposely over expose a shot and see if you see any blinking. If all else fails look it up in the bible...err manual. Dont put too much faith in this feature though, sometimes it'll blink highlights when there is simply no way to avoid them. In the end it's up to you and what you want out of a certain photograph, that all comes with time and most of us are hardly close to that.

[Jon]

IIRC you only get "blinkies" when you've selected Histogram view (while reviewing a picture, press "Info" until you get a small pic and a histogram; zoom still works normally from there).