[Typo3-shop] Image size problem

[Piotr Burda]

I have a problem with tt_products, where can i change the width and 
height for pop up image of products. Now all my images with width > 
400px are displayed as 400 px width, the height of images is very 
strange, example:
original image: 1438 * 231
pop up image: 400 * 231

another original image: 2364 * 484
pop up image: 400 * 400

Where can i change this?\

NB
All other image "manipulations works fine, by example:
plugin.tt_products.maxW_list = 300
plugin.tt_products.maxW_single = 220
plugin.tt_products.limitImage= 3
plugin.tt_products.separateImage= 1

works ok

Best regards

Piotr Burda