Focus Shift is an optical problem that occurs due to Spherical Aberration, when an object is brought into focus at maximum aperture and captured with the lens stopped down. Focus shift can lead to blurry images and focus errors, when working with subjects at close distances and using fast aperture lenses. With the lens aperture fully open or “wide open”, incoming rays of light converge at different focal points due to spherical aberration along the optical axis, as shown in the top illustration below:
Spherical Aberration is an optical problem that occurs when all incoming light rays end up focusing at different points after passing through a spherical surface. Light rays passing through a lens near its horizontal axis are refracted less than rays closer to the edge or “periphery” of the lens and as a result, end up in different spots across the optical axis. In other words, the parallel light rays of incoming light do not converge at the same point after passing through the lens. Because of this, Spherical Aberration can affect resolution and clarity, making it hard to obtain sharp images. Here is an illustration that shows Spherical Aberration:
Everybody is talking about The Cloud – it is on television and radio, in magazines and newspapers, and has been flooding the Internet, presented as a revolutionary technology that will shape up the future. For most people, cloud computing means nothing, since the words “cloud” and “computing” sound very confusing and only make it seem like something overly geeky and out of reach. While the actual technology behind the cloud can be complex, the concept of cloud computing is actually quite simple to understand. In this article, I will explain cloud computing in very simple terms and talk about cloud storage for photographers – what it can offer to us now and in the future, and whether we should be taking advantage of it today.
Camera lens filters can serve different purposes in digital photography. They can be indispensable for capturing scenery in extremely difficult lighting conditions, they can enhance colors and reduce reflections or can simply protect lenses. Filters are widely used in photography and cinematography and while some only use filters in rare situations, others rely on filters for their everyday work. For example, landscape photographers heavily rely on various filters, while street and portrait photographers rarely get to use them. Since digital photography is all about the quality and intensity of light, lens filters are often necessary to modify the light before it enters the lens. Many photographers think that some of the built-in tools in Lightroom and Photoshop can simulate filter behavior, making filters redundant in the digital age. As I will demonstrate below, some filters in fact can never be simulated in software and some actually help in getting even better results during post-processing. In this article, I will talk about the different types of lens filters available, what they do, when and how to use them.
I often get plenty of dust behind the rear element of my Nikon 24-70mm f/2.8G lens. While for the most part it does not affect my images, after my last trip to Utah, I ended up with a large dust particle that somehow made it into the lens. Nikon only removes dust from lenses if you pay for the service, because the normal lens warranty does not cover dust removal. I did not feel like waiting for a couple of weeks and paying a hefty sum to get mine cleaned, so I decided to do it myself. In this video, I will show you how to remove dust from the rear element of the Nikon 24-70mm f/2.8G lens in less than 5 minutes.