Rich Ditch's Photography Blog

February 22, 2009

Photomerge Magic

Tree at Boyce Thompson Arboretum  with 300mm

Tree at Boyce Thompson Arboretum with 300mm

When I walk around looking for birds to photograph I’m generally ill prepared for much scenic photography. My “bird rig” is a 300/2.8 with a matched 2x converter mounted on a Nikon D200 body, all supported by a Gitzo carbon fiber tripod, a Really Right Stuff BH-55 ball head, and a Whimberly Sidekick gimbal arm. I also carry my SB-800 flash, a 1.4x converter, a spare camera battery, extra compact flash cards, and at least one 500ml water bottle in a fanny pack. So there’s not a lot of room (or desire) to pack additional shorter focal length lenses to handle sweeping scenic views.

Yesterday I added an 18-70 lens to my gear “just in case,” and set off on the main trail at Boyce Thompson Arboretum for a three hour hike.

The birds weren’t cooperating, so I spent most of my time enjoying the weather and the views. This tree caught my eye, as it has done many times before: I love the textures brought out by the directional light and the contrasts of tones of wood against rock.

But taking the 2x off my 300mm lens still left me with too much focal length, so I couldn’t get the composition I wanted of the complete tree against the background. I compromised with the image at the top of this post – full frame focusing mostly on the main trunk. Unfortunately, there’s too much texture in this image for it to compress well and show at this tiny 720 pixel web size, so you’ll have to imagine what it really looks like.

I thought of using the 70mm end of the short zoom, but that was too wide for my tastes. What I really needed was something around 150-200mm which I didn’t have with me.

Then I remembered the Photomerge function of Photoshop that combines separate images into one larger version. It is most often used to create panoramas. Its not something that I get to use with my bird photos, and I’d only tried it once with two images just to see if I could make it work.

So, I locked in focus and exposure with the 300, and took a set of 24 overlapping images of the tree. I didn’t know how much overlap to use, and I’m sure I could have gotten away with 16 or maybe 12 or even 9.

After transferring all the raw files to my Mac (an old G4 PowerMac with 1.25 GB of ram and a 1.25 Ghz single processor) I opened all 24 raw files in Adobe Bridge and selected Photomerge from the pulldown menu. I expected an error message, but the G4 decided to give it a go. Two hours later it was finished building a 1.28 GB photoshop file that was 67MP large! I flattened the image and cropped it to 7713 pixels by 5731 pixels – what you’d get with a 44MP camera.

This is big enough to make a 24″ by 32″ print at a generous 240 dpi setting, and it overflows with detail. Here’s a 720 pixel version that suffers from compression just to show the resulting composition.

Tree from Photomerge

Tree from Photomerge

I now have a new technique that I can use as needed, and next time I’ll be smarter about the overlap I use. I’ll also be sure to do the raw conversion of each file separately before I feed them to Photomerge.


1 Comment »

  1. Wow!


    I never thought of using the photomerge utility for that.

    That could possibly make a huge print.

    Great work! Thanks for the tip…

    Comment by ForestWander — February 22, 2009 @ 7:33 pm

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