After some testing with different size of pictures ( 2.4Mb; 2.06 Mb; 1.99 Mb), it appears that maximum upload picture size is 2.0 Mb and not the 5.20 Mb stated in the upload instructions. See post
Donetta for more detail.
Also, should you make an upload, get a notification the upload was successful but DO NOT get another page with a
Red Process button; Then picture will not be processed into the Gallery. ... The upload was to the forum processing software, but because of size or another problem the picture was not placed into the Gallery for use.
Also, I believe the forum photo processor will resize large photos to a smaller forum standard. The 1.99 Mb photo I uploaded was down-sized to 97 Kb. If this is true I see no reason for the photo size upload limit (unless there are other software limitations).