: HD box or TV causing the problem?

2008-12-16, 12:36 AM
Hi all --

I recently got a Scientific Atlanta Explorer 8300HD digital box and a Sony 40" LCD TV. This is sort of a strange issue to describe in words -- when I change the channel, or when the shot changes from high contrast to a lower contrast, it seems like the TV tries to compensate for it. If there is a change in the picture, I notice a quick jump where it lightens or darkens things. I've checked the optimization menus and whatnot in both the TV and the digital box and everything seems to be disabled.

It does this on both HD and SD channels. I'm using composite cables to connect the digital box to the TV.



2008-12-16, 07:35 AM
There's certainly no setting in the 8300HD that would do that.

What is the specific model of the TV?

2008-12-16, 08:30 AM
I suspect what you're experiencing is a "normal" effect of LCD. Remember that LCD works by blocking a back light... so if the picture changes quickly from light to dark, the TV needs to compensate by lowering the intensity of the back light. Different TV's no doubt tackle this differently... but its an unavoidable necessity of the technology. My Sharp 37" does something similar, but I hardly ever notice it... are you sure you're not noticing it more because its new and you're watching for everything like a "hawk". :-)

To try to reduce the amount you notice the effect you can probably play with the light level in the room (my TV senses this, yours may as well) as well as the overall brightness of the display. Also, play with the settings... most Sony TV's have a display mode, with values something like "Movie", "Dynamic", "Game", etc... Try the different modes... I suspect if you're on Dynamic, it might make the effect more noticeable.

By the way, once OLED's come down in price, and you can get a TV made of them, this should no longer happen... OLED's produce light themselves... so there will be no backlight... which also explains why OLED TV's are so damn thin! (If you're into thin :-)

2008-12-16, 09:55 AM
1. I assume you're using component video cables.

2. There is usually a setting in the TV for some form of automatic backlight compensation or automatic contrast or room light compensation. Sometimes this is "hidden" in another part of the setup menu or under "advanced" settings. Depends on the model of the TV.

See the following post on the proper setup of the TV:


3. I've moved this to the LCD forum, since it's not a Rogers issue.

2008-12-16, 07:12 PM
Thanks for the replies.

PlaceHolder, indeed I do look over new toys like a hawk, but this just seems sort of odd! My other HDTV is a plasma so indeed the technology is a lot different.

The TV is a Sony KDL40S4100. I turned all off the enhancement/optimization options and lowered the brightness a bit -- it still does this funky contrast change.