can i convert movies from iPad to mac laptop

Ihave download a movie from ipad but it will not play on my mac air laptop with quicktime installed..??

Are you going to give us any additional clues as to what you are really asking here?

1) The "HT5409" in your subject title reference implies you are dealing with AVCHD content. If true, then how did you transfer them to your iPad and how did you transfer them from your iPad to your your MacBook Air platform? As the HT409 topic clearly stated, this can be very important. In addition, how are the files stored? For instance , have you extracted the MPEG-4 AVC content as transport streams or is the content still in the device recorded file form? Are you trying to edit the content or convert it to M4V, MP4, or MOV files directly?

2) The "can i convert movies from iPad to mac laptop" part of your subject title is confusing. Yes, AVCHD files can be converted to simpler MPEG-4 AVC content that is compatible with all current and most older Mac computers and Apple mobile devices in MOV, MP4, and/or M4V file formats. However, how you do this will depend on the current form of the data and the target settings you wish to employ to ensure compatibility with the various target device possibilities. Further, non-AVCHD content (e.g., HD iPad video recordings) can also be downconverted to simpler settings in a similar manner if needed or required if that is your questing.

3) Depending on your operating system, both AVCHD and MPEG-4 AVC content should already be compatible with QT X v10.2 and v10.3 players if properly transferred to your laptop from the recording device. And, even if improperly transferred, may still be converted to useable/compatible formats as long as the file itself has not been corrupted by your, as yet, unspecified workflow.

4) What does "will not play on my mac air laptop with quicktime installed" mean here? Are you trying to play an AVCHD movie in the QT 7 player or one of the QT X players? If the latter, which one? Are you getting any error message? If so, what are they? If not playing in your main user account on the computer, does it play useing a different account? Do the files play in other, third-party multimedia players?

Basically, your question is the equivalent of my saying my car won't start but failing to mention whether or not I am out of gas, my battery is dead, or that I have removoed the distributor cap, wires, or spark plugs from the engine. To properly solve the issue we need all possible information that you can provide describing exactly what you are doing, how you are doing it, what is not working as your expect it should, and what your goals are. In cases where you cannot answer such questions, it is often helpful to simply post/upload a sample "problem" file and let other users here examine it to determine the problem and/or suggest a specific solution for your particular system/configuration combination.