Just a quick question--have you turned on rulers in Acrobat? And does your image come up the same size as your original in using the ruler -- not looking at your image on screen.
Second question, one of your screen shots shows uncompressed print -- and the other shows hight quality. Did you try working with the different settings? and did you get the same result? My go to setting is Press Quality (but that is just a personal preference when I go to print).
The reason I ask is that sometimes you can't always judge your image by looking at the screen--especially when you are going to print and have a specific size you are planning for.
And, your screen shots were great.
Let us know if you've tried these things already and how it worked/didn't work.
There's nothing wrong!
Photoshop doesn't show you print size - that's not what 100% means. It means one image pixel is represented by one screen pixel (1:1). Acrobat, on the other hand, shows you actual print size, at the ppi setting you specified in Photoshop.
Uncheck "resample image" and set the ppi value. This determines print size, you see the resulting size directly in the Image Size dialog. For print somewhere between 240 and 300 is usually appropriate.
Here's the very same file at 300 and 96 ppi:
What "print size" is in Acrobat, is based on the number Acrobat uses as screen density. I'm not sure if it just assumes 72, or reads from the system.
I guess I don't know this whole thing as well as I thought, because it turns out this was correct. I checked at work this morning and as it turns out what I thought was 100% on all my "correct" postcards was just an automatic zoom to fit the screen. Actual 100% was about the same size as my other exports. Don't I feel silly now.
Thanks for all the help.