For ages I’ve been taking screencaps and they automatically save as .tiff files. Some apps/uploads don’t like .tiff files so I usually end up bringing them in to Photoshop and saving them for web which is a pain and way more time consuming than it needs to be.
So after some googling this is how I fixed it.
Open a terminal window by pressing the apple key and spacebar and typing ‘terminal’. Then paste the line below.
defaults write com.apple.screencapture type jpg
Once you have done this, paste this line to make the changes take effect.
Now press Apple + Shift + 4 to grab a portion of the screen and watch it save as a jpeg!
You’re welcome :)