Large Format Quality from a Small Format Sensor

Composite of 28 images. 1/25 sec at f/11, focal length: 102mm, ISO 100 - May 12, 2008, 5:57pm PDT
Photographed with Canon EOS 20D, Tamron AF 18-200mm f/3.5-6.3 XR Di II, tripod mounted

This image of Yosemite Valley is a composite of 28 images with an 8.2mp sensor. The result is a file that can be printed at 30"x66" at 300dpi without resizing! So for those that are looking to achieve large format prints but can't afford the latest high megapixel medium format digital camera or are unwilling to lug around a large format film camera, do not despair. With a little bit of planning and familiarity with the equipment you have you'll never be limited by print size again, no matter what the pixel count may be on your sensor.

Click thru to read more and see a 100% crop of Bridalveil without any resizing.

The lens I used was a Tamron 18-200mm (super zoom). OK at doing everything, but not great at doing anything. At either extreme, the lens is soft and has chromatic aberration, but right in the mid-range with an f-stop of f/8 or 11 the lens doesn't do so bad. Knowing this I went with a focal length of right around 100mm at f/11.

Usually for composites, I've found that you'll get the best results by photographing in the vertical position (less distortion from side to side, which makes for easier stitching). The only other thing you need to do to have near certain success with a multiple image photomerge is to make sure that your tripod is level and that it remains level as you pan from left to right. The Bogen ball head that I use has a spirit level on the plate to ensure that the composition is level. It would be even better to have a level on the legs to ensure that those are level as well (it would just make the process a little faster/easier is all). You can also use a hot shoe bubble level, such as the Manfrotto 337 Bubble Level.

You'll want to set your camera to manual to ensure that your exposure is consistent throughout. And if you're shooting in jpeg, which you shouldn't be, then you'll want to take your camera out of Auto White Balance mode so that your color temp will also remain consistent.

As you begin to photograph your subject, allow yourself at least 20% overlap between frames. What I usually do is pick an object about 1/4 of the way in from the edge of the frame and track that object as I pan until it is 1/4 of the way from the opposite edge of the frame. Doing this will give your software enough information to construct a seamless composite without any noticeable artifacts.

To stitch the images, I brought them all into Adobe Bridge, selected the 28 images that I needed to complete the composition and opened them in Adobe Camera Raw. I then set the white balance to Daylight since I was shooting in RAW to make sure that I had a consistent white balance throughout each image. I then hit done, not open images, and while in Adobe Bridge again, with all 28 images still selected, I went to Tools>Photoshop>Photomerge.

This will then open Photoshop (I use CS3, which has so far provided far superior results with Photomerge over previous versions). In the dialog that comes up, on the left hand side, leave Auto selected. Make sure that all of the images you want are included in the list. If there are images that weren't included add them through the dialog and remove any that were accidentally included. Hit OK and now you play the waiting game.

Once the file opens it will be unflattened. I suggest looking over the entire image at 100% to ensure that the stitch was clean and up to your standards. If so flatten the image and save. Now look at the image size and be amazed.

Below is a 100% crop from the original image without any resizing. Not too bad for a low megapixel camera and an inexpensive lens.