turn off image text?

Yes, it would be nice, but that would mean another database table, with code for coordinating which image has which alt and title and displaying them in the correct places.
The zen_image() function handles images sitewide, so you would be suppressing title tooltips on all images, or adding code to run every time an image is displayed to decide how the title should be handled. If you want to try it, you can find the function in
/includes/functions/html_output.php

Line #159 : function zen_image($src, $alt = '', $width = '', $height = '', $parameters = '') {

There is no override for this, so save a backup.

Thanks for your help Glen, sorry it took me so long to reply.
I did end up digging around in that file (after saving a backup)
I found if I tweaked the second reference to title= it gave me the title="" that I was after, it did remove the tool tip site wide, but it just looks a little more professional to me. None of the images really needed "explanations" and the alt tag is still there in the source.
Thanks again,
David