CustomObject photo

Hi

I'm trying to upload a photo to a customObject using the acs API.

I managed to upload a photo to the 'Photos' Table, but not to the customObject.

When running the following code to upload an image to the photos table i eventualy see the image and can get it back.

Cloud.Photos.create({
        photo: Titanium.Filesystem.getFile(imageFileName),
        user_id: exports.currentUser.id,
        },

However, when trying to attach an image to a CustomObject such as below i can't find the image online.

Cloud.Objects.update({
            classname: 'CustomObject',
            id: objectId,
            fields: {
                    photo: Titanium.Filesystem.getFile(imageFileName)
                }

Any advice or code snippet to update a customObject with a photo would be appreciated. Thanks