Bob Dolph Answers Questions on LCD Monitor Burn-In, Outdoor Camera Focus

Q: I thought I was seeing things. I have an LCD monitor and there is an image burned on the screen. I thought this wasn’t supposed to happen with this type of technology. What can I do remove the “burn-in.”
A: I was surprised to hear about this myself. According to one LCD-monitor manufacturer, image burn-in or image “persistence” can happen on LCD monitors. Unlike CRT monitors, it is not permanent.
To recover from this, leave the panel off for an extended time. A screen saver is also recommended when the monitor is not in use.

Q: What is the best way to adjust focus on an outdoor camera with an auto iris lens in bright sunlight?
A: One way is to get some dark welding filters and put them over the lens to simulate nighttime. You will want to get the auto iris lens to open up fully for focusing or you will get a fuzzy picture at night.
Another way is to either get a “neutral density filter” or less expensive polarizing filters (you will need two and twist them to get maximum darkness) from the camera store. I have, in a pinch, taken some polarized sunglass lenses out of the frame, put them together, and twisted them at right angles to get maximum darkness. Another suggestion is to just adjust your focus at night.
If you still cannot get a good focus at night and day, then you may have to adjust the manufacturer’s set back focus adjustment on the camera lens. Also, note that some manufacturers now provide a way to open the iris all the way while adjusting for back focus. One that comes to mind is the “Lens Wizard” feature on all Bosch fixed cameras.


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