Small areas of image flashing in D90 lcd viewing screen

2

2e4

New member
Hi everyone

Just purcahsed 2nd hand D90 and have been trying it out and have noticed this fault in
the viewing screen small areas of flashing on certain areas of images does not occur all the time.
Doe this suggest a faulty screen, i have removed card and installed on PC and images are fine.
your advice would be much apprecieted as I am a newbie.

Many thanks

Mick...................:culpability:
 
D

Deezey

Senior Member
The screen flashes when the light parts of you picture turn to pure white. What the screen is telling you is you lost all the information in that part of the shot. As in its just pure white with no detail. (Making blond hair look more like a helmet because of loss of texture.)

When you see the flashing screen just adjust your camera to shoot a darker exposure. Take a new picture. Recheck to make sure you don't have any flashing bits on the new picture and you are good to go.

A quick tip. You will be more successful pulling detail from an underexposed photo than an overexposed. Once it goes all white you are pretty much toast.

Sorry if you knew all this.

Sent from my SCH-I405 using Tapatalk 2
 
2

2e4

New member
Hey guys
Thankyou so much for the quick replies, cannot wait to get out there and learn I have some serious reading to do
Have a great day all.

Mick.......
 
M

MrF

Senior Member
Deezey said:
The screen flashes when the light parts of you picture turn to pure white. What the screen is telling you is you lost all the information in that part of the shot. As in its just pure white with no detail. (Making blond hair look more like a helmet because of loss of texture.)

When you see the flashing screen just adjust your camera to shoot a darker exposure. Take a new picture. Recheck to make sure you don't have any flashing bits on the new picture and you are good to go.

A quick tip. You will be more successful pulling detail from an underexposed photo than an overexposed. Once it goes all white you are pretty much toast.

Sorry if you knew all this.

Sent from my SCH-I405 using Tapatalk 2
Click to expand...

To nerd out on this a little more, digital cameras approximate the billions of colors in the real world using three channels (red, green, and blue) with 256 'values' of brightness each (0-255). A pixel will flash on the highlight screen when it hits a value of 255. Some cameras will let you see highlights (and histograms) for each individual channel, some just show you one. I have no idea how the camera comes up with the value for the total histogram, although some folks will tell you that it's just the green channel, and the histograms do look similar to each other. A good example where this can bite you is a sunset. I usually see the 'total' highlights look fine, but the red channel is completely blown out around the sun. If the D90 will let you view the individual channels, I'd get in the habit of checking that.

You can also look at the histogram to get a gauge on how much to adjust the exposure. If you have a ton of pixels on the right side (i.e. a value of 255) you'll have to dial in more -EV than if you just had a small spike there.

Hope this helps!
 
W

WayneF

Senior Member
MrF said:
Some cameras will let you see highlights (and histograms) for each individual channel, some just show you one. I have no idea how the camera comes up with the value for the total histogram, although some folks will tell you that it's just the green channel, and the histograms do look similar to each other. A good example where this can bite you is a sunset. I usually see the 'total' highlights look fine, but the red channel is completely blown out around the sun. If the D90 will let you view the individual channels, I'd get in the habit of checking that.
Click to expand...

Right, only look at the three individual histograms, the three RGB channels. The one single composite RGB histogram is NOT actual data, but is instead a computed luminance simulation (representing apparent brightness to human eye). It rarely even shows clipping. It is not just the green channel, but our eyes are rather sensitive to green, so the green channel is weighted heavily in the brightness computation. The simulated composite is never of interest to us.

The real data is in the three individual channels. They show the actual real data, the only thing that counts.

Two types of Histograms
 
M

MrF

Senior Member
WayneF said:
Right, only look at the three individual histograms, the three RGB channels. The one single composite RGB histogram is NOT actual data, but is instead a computed luminance simulation (representing apparent brightness to human eye). It rarely even shows clipping. It is not just the green channel, but our eyes are rather sensitive to green, so the green channel is weighted heavily in the brightness computation. The simulated composite is never of interest to us.

The real data is in the three individual channels. They show the actual real data, the only thing that counts.

Two types of Histograms
Click to expand...

That's a great link, thanks, Wayne!
 
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