Q: How can I transfer photo files from iPad to iMac?

Connect your iPad to your compute open iTunes, then click on your iPad in the left window, click the photo tab then make sure the sync photos check box is checked.  If you have a lot of photos you make want to select only a few albums. 

Here is the article for that:

http://support.apple.com/kb/HT4083

I thought thats what icloud does automatically? why would you need to wire them?

I Have iCloud also. My photos pass automatically between my iPhone and iPad but they don't go to my Mac like their supposed to. The expert at the Apple Store said to put all three devices next to each other and then do some things that I didn't understand.

Clutterbuns wrote:

 

I Have iCloud also. My photos pass automatically between my iPhone and iPad but they don't go to my Mac like their supposed to. The expert at the Apple Store said to put all three devices next to each other and then do some things that I didn't understand.

http://www.apple.com/icloud/photos/

iCloud Photo Library FAQ - Apple Support

Another idea: if you just want to do some or occasionally, you could also easily airdrop them - that works like a charm and is very fast.

Use AirDrop to send content from your Mac - Apple Support

Why don`t you just open the photo app on you Mac and import them from you iPad?

You have to enable "Photos" under iCloud setting in System Preferences and make sure "iCloud Photo Library" is checked. Then go to Photos app and open "Photos->Preferences->iCloud" and select appropriate item "Download originals" or "Optimize Storage". Be sure to use correct photos library.

If you want to do this manually, you can use Photos, iPhoto, Aperture etc' import function while you iOS device is connected to your computer via usb. You can also use Image Capture App (built in app of Mac OS X).