A photoblog is optimized for photographs or digital creation with very little attention to the text. Like a photographer who keeps the background out of focus and avoids clutter while composing a portrait, photoblog needs a very clean and clutter free theme to provide more attention to the images. Also, there are many ways people would want to showcase their images, some would like their images framed, or sharing an entire gallery with a slideshow, some might like to showcase them big (atleast 800×600), or on a black background.

Here’s a list of such wordpress themes (free) which are actually good for publishing photographs or images in some form of a photoblog.

Photo-Blog wordpress theme

• Specially made for photo blogs
• Single column design
• Unique design
• xhtml valid
• Widget ready
• Collapsible navigation
• Minimalistic design

PhotoBlog

• simple
• single column
• fixed width
• minimalistic design
• supports changing the background color to enhance the Photo

Nishita

A very simple and elegant PhotoBlog theme.

Nautilus

Grain

PhotoWP

Click – Polaroid – Simplet – Spotless - MonoTone

• These are more or less same and provide a neat experience for showcasing photos.
• Single Column
• Very simplistic
• Clean designs
• Dark backgrounds and borders
• supports image size of 640×480, could be increased by editing the css.

Apart from these themes there are some wordpress plugins which will be of great help

1. YAPB (Yet another Photoblog plugin), There is a list of some free themes here which support this plugin.  

2. PhotoQ

On the last note, if you use wordpress for your blog and interested in maintaining a photoblog the Photoblogs and Galleries page is pretty good to start.