When you select “Edit with Photoshop”, LR doesn’t have to render out the data like it did in 1.0, instead it uses ACR to do this and open the doc in Photoshop. So obviously the version of ACR running in Photoshop has to be in sync with the raw processing features in LR. So say you have CS4 and LR3. That older version of ACR doesn’t have lens correction so it will not be applied although you can still use the “Edit in Photoshop” command. The alternative is to render out from LR itself (Export). Then open in Photoshop and of course, you’ll get your lens correction.
This architecture is kind of nice because Adobe doesn’t force you to upgrade Photoshop to match LR. But if the two are in sync, its faster to have the option to use the Edit in Photoshop option.
How come we don't have an option to open in ACR when we select "Edit with Photoshop"? Unless I'm missing something, we're forced to finish the RAW edit in LightRoom. I imagine I could open it as a smart object...
