Q: HELP, I have a Macbook Pro 15in Mid-2010 and I want to connect it to an iMac 27 inch mid 2011, what cables do I need?

How do you want to connect two macs?

For data sharing, you need no cable. Connect both macs on the same (Wi-Fi) network then turn on file sharing on one of the mac.

But, if you want to use the target display mode ( use iMac as external monitor for Macbook Pro), I believe you have no option.

Your iMac requires Thunderbolt on the other mac, but you Macbook has Mini DisplayPort, not Thunderbolt.

Use your iMac as a display with Target Display Mode - Apple Support

MacBook Pro (15-inch, Mid 2010) - Technical Specifications

I searched around on Web but no hardware/cable solution found.

Only solution I found is by software, ScreenRecycler.

https://www.screenrecycler.com/ScreenRecycler.html

It seems that it runs on the mechanism similar to Screen Sharing.

I have no experience with the product. So, I have no idea whether this works for you or not.

It's not free, but you can evaluate it with free trial version if you are interested.

Get a Thunderbolt cable and connect the two Macs using the Minidisplay port on the MBP and the Thunderbolt port on the iMac.

https://support.apple.com/en-us/HT204592

Ciao.

You can share screens using the built-in Sharing preference pane. Simply check 'File Sharing' on the Mac whose screen you want to share. Note the Computer Name. Under 'Users' you can select who can access the screen.

Then on the other Mac you can open that screen in a window as described in this Apple Help page:

OS X Yosemite: Share the screen of another Mac

I use an AppleScript Application with the following code:

property targetMacsIPName : "Macbook-Pro.local"

tell application "Screen Sharing"

  GetURL "vnc://" & targetMacsIPName

end tell

I've viewed the screen of a laptop running Tiger on an iMac running Mavericks. When the cursor is inside the Screen Sharing window you can control the remote Mac with the mouse and most keystrokes.