If this isn't the correct forum to get this answer can someone point me in the right direction. I know I can use Iphoto or Aperture and ICloud but can I do it somehow using LR4?
Yes, it's possible, but not as cleanly as Apple products do it. You can see an example in this video tutorial by Russell Brown http://tv.adobe.com/watch/the-russell-brown-show/exporting-adobe-light room-3-images-to-an-apple-ipad-portfolio-/
I haven't used it but read a review the other day about a Lr Publishing plugin (it's donationware) for exporting files to the iPad offered by Jeffrey Freidl ...
I export at full resolution and let the iPad resize it. The problem is that you don't know exactly what res the iPad wants (it may have a pixel or two of border) and it's best to just resize once.
Ashvin Ghisyawan wrote:
Isn't it easier to export the files (for example) the ipad resoltion, 72dpi jpg and then transfer it to de ipad?
That may not be the best option ... as the iPad, iPad 2 have a screen resolution of 132 ppi, and the new iPad has a screen resolution of 264 ppi ...
I find it is quite easy to export at the optimum resolution for the device from Lr to a folder ... then load from that folder in iTunes ... then when a client/viewer does a pinch to zoom on an image, you have a bit more resolution to carry the day vs 72 ppi .... plus ... the export sharpening in Lr is based upon the chosen export resolution ... if you export full size, and allow iTunes or the device to resize, there is the potential to lose some definition because the export sharpening was applied at the native resolution ... and may not be optimized for viewing on the device in question ...
It is quite easy to create an export preset, so you can quickly create the files for viewing on other devices ...
The problem is that you don't know exactly what res the iPad wants (it may have a pixel or two of border) and it's best to just resize once.
All sources seem to agree it's best to export at the native resolution 2048/1536px for images to be viewed at 100%. I generally export at 2048px for the long side and it looks fine to me. Sure, if you want to be able to zoom in you could export at full resolution.
As with images for the web it's the absolute pixel dimensions and not the PPI that's relevant.