Preview Zoom

I’ve just started imaging with a ZWO 6200, (60 Megapixel).
When a preview is shown , SGP zooms to show it fullscreen, on my 1920x1200 monitor, this is about 15%. If I zoom in to pixel peep and then zoom back out, the most I can go back to is 25%.
I’m on version 2.7, do the more recent versions treat large (huge!) image files differently?

Huw

Must have been particularly blind last night, the button in question was right there in front of me.

Huw