I have a rotatable display which I tip up so that I can fit more code on the screen.
However any text on the screen looks just the slightest bit less sharp on the rotated display. Can anyone tell me why this is, or better yet, how to 'fix' it?
That's probably to do with the ClearType settings.
ClearType uses subpixel antialiasing to smooth the edges of fonts. When you rotate the display the groups of red green and blue pixels will be in a different pattern (rotated through 90 degrees) but the operating system probably doesn't know about that.
http://en.wikipedia.org/wiki/Subpixel_rendering tells you all about subpixel antialiasing
This is probably caused by ClearType.
You may either :
One thing that could be a problem here could be due to the fact that the way due to how TFT monitors are made gives them a very limited range of viewing angles, typically they are optimized for viewing horizontally and look distorted when viewed from above or below.
From this Wikipedia article on TFT LCD monitors manufacture:
The "less sharp" impression could be due to Cleartype as others have mentioned, but could also be due to your monitor having a vertical viewing angle that is very poor. This vertical viewing angle would become a horizontal viewing angle when the TFT is rotated. What this would mean is that your eyes would be seeing two different sets of colours and your mind is blurring them as it merges them together.
I would expect this to have gotten better in the last few years as manufacturing processes have improved.
I was having the same issue, and can confirm it had nothing to do with ClearType which I've played around with, tried disabling it altogether etc.
The solution: After changing the orientation to Portrait and rotating the monitor, and I discovered it by accident, all I did was turn off my monitor and turned it back on again. It then performed some kind of "auto adjustment" and immediately solved the problem. Display is once again clear and sharp just like in Landscape mode.
Some monitors may not do this on auto, so you may have to look for an auto-adjustment or auto-calibration setting of some kind in the monitor's menu.
Have a dual monitor setup, one horizontal and one vertical (which had this problem, it's a DELL 2209WA).
Hope this helps someone out there, good luck! :)