Is it possible to tighten the zoom like in the example link below. For the example we are using a 500x369 photo.

www.ebay.com/itm/E-Glide-Electric-Skateboard-AT-Aluminum-Deck-Off-Road-/111233555698?pt=LH_DefaultDomain_0&hash=item19e6095cf2

What you mean by "tighten"?

In the example you gave,
The thumbnail is (500x369): i.ebayimg.com/00/s/MTE4MVgxNjAw/z/QtwAAMXQlgtSomJz/$_12.JPG
The large picture is (1600x1181): i.ebayimg.com/00/s/MTE4MVgxNjAw/z/QtwAAMXQlgtSomJz/$_57.JPG

So, 500:1600 = 1:3 zoom ratio is perfect for using the zooming functionality.

The large picture must be large enough (2 or 3 times larger than the thumbnails). If you are using 500x369 large picture and your thumbnails are around 400 pixels in the product details page. Then "zooming" won't actually zoom the picture.

You might try the "MouseWheel" zooming (which is a digital zooming) like you see in here: demo.flexiblewebdesign.com/fashionmart/index.php?option=com_virtuemart&view=productdetails&virtuemart_product_id=50&Itemid=537

By the time shoppers increase the zooming rate by the mouse wheel, the zoom will magnify the pictures. (but since it will be digital, there will be quality loses, a lot... and not recommended)

Regards.
Support