Can i use my Apple thunderbolt Display 2011 with a imac 5k or 4k ?

You can use it with Macbook with USBC thunderbolt 3 -> thunderbolt 2 Adapter .The Apple thunderbolt Display 2011 uses Thunderbolt1 not 2.Same here about the thunderbolt display being good.Why i asked the question is because i was thinking of buying a 4k or 5k IMAC but from what i have read it is not possible to do that.

Retina 5K: iMac Target display mode and Thunderbolt displayTwo of the questions we're still getting asked a lot is whether the Retina 5K iMac

can be used in "target display mode" as an external monitor for a new

Mac Pro or MacBook Pro, or whether Apple will be releasing a 5K version

of their Thunderbolt display any time soon. Sadly, as I tweeted right

after the Apple's October Event, and later explained, the answer to the first question is, sadly, "no", and the answer to the second question is the same. Why is that?Intel claims that the continued delays with Broadwell won't affect Skylake, but I'll be that when they ship it.

With the iMac, Apple can ignore the standards and fuse the two

DisplayPort 1.2 pipes internally with their own custom timing controller

(TCON). With external displays, they can't. So, we're capped at 4K

until Skylake. After that, we'll still need new Mac Pros and new MacBook

Pros with Skylake chipsets and Thunderbolt 3 ports. Then we'll be able

to drive 5K and then, hopefully, Apple will release a Retina 5K

Thunderbolt display.So i will wait to get a 2013 i7 4771 as a reasonably price around 750 pounds for a 8gb.It would have been nice to get a later modal but as it would make my Apple Thunderbolt Display

redundant i will have to go for the 2013 modal.The only other choice is going for the 2018 Mac Mini

it is a shame it doesn't have inderpendent graphics rather than the built in Intel one.

Thanks for your answer, that was very helpful. so what it means is on the thunderbolt display it want fill up the whole screen like in your photo.What is the difference between this and Target display?. Can you get all the stuff on the 5k on the thunderbolt display it will just take up less space on the screen ?IF i was to buy a 4k modal i take it the picture on the thunderbolt would be even smaller than the 5k model .Am i right to assume that?Atlest you have proved it can be done.i asked the same question on Macrumors forum but got zero response.

i now that the 21 4k is smaller than the 27 5k.I do have the Apple thunderbolt display using it with my Mac Mini 2012.My question is would the 4k modal which is lower resolution show up smaller than the 5k one on the Thunderbolt display.The reason i asked the question in the first place is because i was thinking of getting a 5k modal.You see i don't want to get rid of the Thunderbolt display.

So what about a 4k modal on the Apple thunderbolt display am i right to assume it would be even smaller on the Apple thunderbolt display than the 5k modal.?