Q: Can I use iPhoto 9.4.3 when I upgrade from Lion to Yosemite

No.  You will have to update to iPhoto 9.6.1 from the App Store after upgrading to Yosemite.  Follow the directions posted by Tererence Devlin in this post:

Terence Devlin

Apr 14, 2015 11:21 AM

Re: Is Iphoto gone ? i want it back!

in response to Johannes666

Recommended

 

Go to the App Store and check out the Purchases List. If iPhoto is there then it will be v9.6.1

 

If iPhoto 9.6.1 is there, close the App Store, drag your existing iPhoto app (not the library, just the app) to the trash and then go back to the App Store.

 

Install the App from the App Store.

 

Sometimes iPhoto is not visible on the Purchases List. it may be hidden. See this article for details on how to unhide it.

 

http://support.apple.com/kb/HT4928

 

One question often asked: Will I lose my Photos if I reinstall?

 

iPhoto the application and the iPhoto Library are two different parts of the iPhoto programme. So, reinstalling the app should not affect the Library. BUT you should always have a back up before doing this kind of work. Always.

Make sure you've moved the current iPhoto application go the Trash bin before going to the App Store.  Also make sure there are no other iPhoto apps somewhere else on the boot drive or on an external HD that is connected to your Mac. 

Do I upgrade to 9.6.1 while I am still on Lion,

No.  You must be running Yosemite before you can get 9.6.1.

what if one started with Lion and iPhoto

upgraded to Yosemite (10.5) including Photos

moved all contents of iPhotos to Photos

Now-- should I just delete iPhotos?

if so, how?

Currently, when I select for a photo

to be placed in "Photos" it appears

in both apps, even though I have

not chosen "iPhotos" as an option.

Both options appear at each

selection time.

Biggest concern is: is having

both apps taking up twice the

space on the computer???

Thank you for your time

and consideration.

Biggest concern is: is having both apps taking up twice the space on the computer???

Photos saves disk space by sharing images with your iPhoto or Aperture libraries - Apple Support

The (hard) link between Photos and iPhoto

Biggest concern is: is having both apps taking up twice the space on the computer???

Photos saves disk space by sharing images with your iPhoto or Aperture libraries - Apple Support

The (hard) link between Photos and iPhoto

What do you think, Old Toad, should one forget about using iPhoto and start using only Photo now?

Don't want to to stuck with everything in iPhotos in future and not be able to use it -is that a possibility?

Or might Photos be upgraded to be so much more attractive I will wish I'd moved over to just using

that app while I still have few enough photos not to worry about loss and migration issues?

By the way, went to Preferences in each of these apps and there is a choice to "import" to that app in

both Photos and iPhotos, if I do not select to import to iPhotos and only to Photos then I believe

that the duplicating imports will stop; am I correct in my reasoning here?

iPhoto is no longer developed. Sooner or later a version of the OS will come along and it will no longer run. It won't be this year but it will happen inevitably.

So, yes, it's time to plan for life after iPhoto. But you don't quite have to abandon it yet, and might want to wait while Photos progresses along its development path.

I'm guessing you're referring to the option to Copy Items to the iPhoto (or Photos) Library on import?

By the way, went to Preferences in each of these apps and there is a choice to "import" to that app in

both Photos and iPhotos, if I do not select to import to iPhotos and only to Photos then I believe

that the duplicating imports will stop; am I correct in my reasoning here?

That is not what this means. iPhoto and Photos are quite unaware of each other. If you import a photo to iPhoto, Photos has no knowledge of it and vice versa.

That option refers to managing the files, and it's quite important.

For more on iPhoto and file management see this User Tip:

https://discussions.apple.com/docs/DOC-6361

If you can I would conginue using iPhoto as long as possible, particularly if you use the Places feature and want to add or edit locations.  That feature won't be available until El Capitan is released along with additional sorting capabilities.  Also you can take the time to organize your photos not only by events but by additional albums so you'll have those albums when you migrate the library to Photos. 

Bottom line is that we'll all have to migrate to Photos eventually and in the meantime organize our iPhoto libraries as best as possible in a manner that will make it easier to located specific photos after the migration.

People are saying that have both and photos importing into both doesn't use more space because they share the library, if I have that right.  So if they unaware of each other, is the system aware of them both and not storing each as separate sets of photos but only using the same amount of space as if only one photo app was there (since they both have the same set of photos in each.)

Sense this as wise advice -thanks.

People are saying that have both and photos importing into both doesn't use more space because they share the library, if I have that right.

You don't have that right. When you first launch Photos it migrates the iPhoto library to its own format. Now you ave two libraries, one for iPhoto and one for Photos. These share the same set of original files. That's where the space is saved. From that point on, the two libraries are quite unaware of each other. So: add a pic to iPhoto, it goes to the iPhoto Library. But it is not in the Photos Library - and vice versa.

So, once the first run migration has taken place the two apps have no knowledge of each other.