Easily Find the No-Parallax Point of Your Lens

The no-parallax points above are measured with a 24-105mm F4 DG OS HSM | Art mounted on a Nikon D810 FX camera mounted on a Nodal Ninja M2 w/RD8-II Rotator. The Sigma 24 – 150 lens was chosen for its focal length range, quality, and constant aperture. The Nodal Ninja was chosen for its quality, price, and availability. The Nikon D810 is a 36-megapixel D-SLR that was very reasonably priced used.

Initially, I started panoramic photography with a Sunway rail but it was woefully undersized for a Nikon D810 and 16-35 mm F4 lens. The rural subject matter I photographed needed a range of focal lengths beyond 50mm. In addition to capturing a complete story in one wide image, panoramic photography substantially increases available resolution and detail in industrial imagery.

The landscape image below benefited from using a 105mm focal length as the subject was in the far distance and the vertical angle of view was small. Using a wide-angle lens would have wasted a lot of resolution and required substantial cropping.

The industrial image below is part of a much larger image shot using a 50mm lens and consisting of 12 images in three rows. The use of a 50mm lens has increased the resolution available as a contrast to the blurred motion of the dairy platform and cows. A 24 mm lens might have covered the entire subject but the resolution would have been lower.

The image was not entirely satisfactory. The 50 mm lens had an angle of view too narrow to capture the human subjects in one frame. This resulted in the same person being on multiple frames and artifacts after masking in PT Gui was used in an attempt to rectify this. The artifact on the left-hand side of the frame is the result of masking out a person because their upper and lower bodies were horizontally displaced after initial stitching.

Initially, I set the no-parallax point ( commonly but incorrectly called the nodal point ) by trial and error. This was straightforward with the Nikon FX 16-35 lens but was confusing with the Sigma 24-105, it seemed hard to establish a definitive no-parallax point so I settled for the 35mm focal length.

The no-parallax point is situated at the vertex of the angle of view or entrance pupil to the lens. This is observable by looking into the front of the lens and stopping down the lens to make it easier to see. (I’ve only tried this with a D-SLR as this has an optical viewfinder and therefore a path for light to come from the rear of the lens.)

After mounting the camera and lens on the Nodal Ninja and centering the longitudinal lens axis over the rotator the entrance pupil can be measured at each of the required focal lengths. I used a pen and my stereoscopic vision to indicate where I saw the entrance pupil along the axis of the lens. Thus indicating the approximate position on the upper rail.

After establishing an approximate no-parallax point I then confirmed and adjusted the final position using the alignment of the edges of two vertical objects. In the past have used a lighting stand and a distant object like an electricity pole or a chimney. I found these unsatisfactory because it was hard to discriminate between them, especially on a grey overcast day.

I spent some time driving around the small town I live in on a sunny day and settled on the edge of a concrete electricity pole 5 meters away and the tall vertical window of a building 30 meters away. Front lit by the mid-afternoon summer sun there was plenty of contrast.

Working through each focal length: observing the entrance pupil then confirming by checking for parallax in the viewfinder. The camera viewpoint is centered so that the two reference points are aligned, this only has to be done once as the lens axis does not change. The camera is then rotated left and right of the center around the apparent no-parallax point. If the objects remain aligned then the no-parallax point is correct. if not a small adjustment will be needed to the position on the rail. I use the view finder rather than live view as I find it easier to see the small differences in the alignment of the two edges.

The no-parallax points in the table above are those I have determined by the method above for the equipment specified. The other parameters have been calculated by the Photo Pills app. I used 8 meters as an indicative distance because the panoramas I shoot on farms are often at this distance from the main subject.

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