Hi,
it would be great if you add the possibility to upload a custom thumbnail for each photo...
for example, for album A I need to show thumbs 100x150? I can upload a custom thumb.

for album B thumbs I need are 200X200? I can upload a custom thumb for that images.

It would be really great and useful I think!

Yes, but not straight forward. (Why would you want a thumbnail image different from the photo?) Anyway, you would have to create a "cache" image in the cache folders.

However you will have to code the custom size in your theme. Please read the theming tutorial. (If all you want is different sized thumbnails, no need to upload any special image--once your theme is coded to call out the differently sized thumbnails, everything else will follow.)

No well, it's a bit difficult to do. Because I need to let user upload images with their own watermarks, and thumbnails without watermark for certain albums; for ex 135x90px thumbs.

While for other albums users have to upload square crops of their photos as thumbnails; for ex 70x70px thumbs.

For other albums then, we need larger thumbs (300x200px).

I know is complicated to explain why we need this but... it would be great to have a custom thumbnail upload form... that's it!

Thank you

You can select to watermark or not by album and so long as every image in the album uses the same watermark that is all you need to do.

A custom thumbnail upload would probably not work for you anyway. You will have to code your theme to deal with the differences among albums no matter what.

But as I said, you can upload pre-formed thumbnails to the cache folders. You just have to follow the normal naming conventions used by Zenphoto. (And of course, be careful not to purge your cache!)

We will NOT be providing a special upload to the cache folder, but there is no reason why you could not build a plugin that did this.

Well the real fact is that my gallery is included in my wordpress site, so I don't use the real zenphoto gallery! I need zenphoto working as a gallery cms for multiple users to upload. And these users don't know how to use ftp.

Well, how is your gallery incuded? Anyway, I guess you need to write some custom stuff for what you need then.

Maybe using/adapting/modifiying a Wordpress plugin like ZenphotoPress or some of the others will be a way for you.

Maybe also take a look at Zenphoto's object model.

I've included with zenphotopress plugin, but I'm not able to edit it to get what I want, I'm not so able with php stuffs.

Sorry, then you have to refer to the developer of Zenphotopress. Please search, there is a lenghtly thread about this plugin that its developer occasionally visits.