Ok, today’s post is going to be uber geeky. If you’re not into photography maybe skip this one!
When working as an architectural photographer or shooting any other kind of panoramic scene that needs to be stitched together, you need to be concerned about your no-parallax point.
What am I waffling on about? Well, sometimes a wide angle lens just isn’t wide enough. Take today for example, I had to shoot a 10 story building from front on. Which meant shooting from literally just across the street. Near impossible without using a fish eye lens and getting a massive amount of distortion.
To give you an idea of how close I was, here’s the scene shot with a 35mm lens (as wide as most compact cameras go):
Here’s the scene, shot with an ultra wide 17mm lens, which still couldn’t do the job:
When that happens, we need to take a series of vertical images which will then be stitched together digitally in photoshop:
Sounds straight forward enough, right? Well here’s where it gets tricky. If the camera is mounted on to a standard tripod, the axis of rotation is miles from the front and centre of the lens:
Therefore when you rotate the camera around to get your series of images, the scene is not actually captured from the same point of view. This causes items in the foreground to not line up with objects in the background at the overlapping parts of each image. This then obviously makes for a nasty stitching job which is far from ideal.
To get around this, you need to use a special panoramic head for your tripod. This dramatically changes your axis of rotation, then allows for very fine adjustment to ensure that every single thing in the image lines up.
The bad news is, you’ll need to set the no-parallax point for each one of your lenses individually. If you’re using zoom lenses then it’ll be different at each point of the zoom as well. The good news is, you only need to do it once! So write down your measurements and carry them along with your gear.
If anyone would like to know detailed instructions of actually setting the no-parallax point, fire away in the comments and I’ll do another post. But for now I think that’s geeky enough!
