ViewSonic- Blurry corners and center

[shadowed]

I have a ViewSonic A91f+ 19" CRT. I noticed popup windows in the center of the screen have blurry text. I moved the popup window around to different positions on the screen and the text becomes clearer. Upon closer inspection, the 4 corners are also blurry.
Does anybody have any ideas how to adjust the focus for these ?
I have tried the front monitor buttons but there is not any focus settings in there.
Is this a common problem with CRTs ?.
This monitor is about two and a half years old now.
Thanks in advance for any help.

 

[Sciberpunkt]

In my (limited) experience, focus adjustment compensates for curvature of the CRT surface and setting it means finding the setting that makes the center and corners of the screen equally sharp. It's a happy medium between a sharp screen center and blurry corners or sharp corners and a blurry center. Sounds like your monitor is set as optimally as it can be.

 

[palatine]

Just thought that I would post this here for the benefit of search engines. When I recently moved to a new machine but kept the same 19" Envision CRT, I noticed the same symptoms of blurry text in the center. I checked the display adapter settings, and the new system (NVidia 8500 GT) had defaulted to 60 Hz refresh rate. I set it back to the 75 Hz that my previous ATi card was using for years. Bingo! Man, what a difference. All blurriness gone, sharp as a tack.

I don't know if this will resolve issues for everyone experiencing this problem. Probably not, if the issue is truly hardware-related. But, it doesn't take long to check, and the improvement is definitely worth the time!

cheers,
scott