How many can I share at a time?

I could not find any Apple document that states the exact number you can share. The terms of use are vague - they only state that there is a limit to the number of photos:

See: http://www.apple.com/legal/icloud/en/terms.html

Apple reserves the right to place limits on the number and/or size of photos that can be uploaded during a given time period in order to limit unintended or excessive use of the service.

.....

Photos in shared photo streams are not deleted after thirty (30) days, but the size of any given photo stream may be subject to photo or recipient number, and/or size limitations. Downloaded photos can be manually saved to the iOS Camera Roll

This says that there is a limit to the number of photos you can share at once - but you can always extend your photo stream later by adding more photos to it - until you hit the unknown size limitation.

Regards

Léonie