This mod requires OptiFine HD_A 1.1 preview version (in the top of the thread).

1. Download and install OptiFine 1.1 (preferably on a clean Minecraft.jar, if you've got a modded one already you can give it a shot but no guarantees this mod will work with an already modded Minecraft).

2. DOWNLOAD v1.1.04 (Windows) or DOWNLOAD v1.1.04 (everyone else) and extract the folder inside the archive anywhere (like on your Desktop). Open the folder, and run "INSTALLER.exe" (or nitrous.jar if you're not on Windows). Click "Install Mods", wait for the mod to finish patching Minecraft.jar. (To anyone with the "javassist.NotFoundException: a(..) is not found in adt" error, just right-click on the "1.0.0 line" in the Installer and disable it.) Once it's done, you should be all set! Run Minecraft and enjoy unbelievable shaders! But keep reading, for there are some tweaks you must make to your video settings to create the best experience!

2b. Make sure you have the latest and best shaders for you found in the Additional Files section below. Shaders Only 1.1 is updated more frequently than the main download and installer.

3. Go to "Options..." and make sure that your FOV is set to Normal (all the way to the left). Then open up Video Settings and then Details and turn off Sky if you want to eliminate shadows being drawn on the sky. Go back to Video Settings and then click on Other, and enable Smooth FPS. This setting will reduce input lag at the cost of fps, some may want this enabled. For better performance, turn graphics to Fast, and then re-enable specific features that you want to be Fancy in the Details section (like trees and grass edges). This gave me about a 7 fps boost even though most things look exactly the same. For some more performance tweaks (thanks to the great community!!) see here and here.