DSLR Purchasing: APS-C vs. Full Size Sensor?

DSLR's sensors are essentially digital “film.” The sensor is the camera's electronic device which captures images.

Sensors contain millions of “photosites,” essentially buckets which capture the light coming through the DSLR's lens. The light is converted to an electric signal which gets measured, optimized, and converted to a digital image by the DSLR's processor.

The size of the buckets (photosites) is important to the sensor's sensitivity and its ability to accurately gather light in a variety of lighting conditions. Bigger buckets are better than smaller ones, because more light can be stored in them, without getting over-filled. Bigger buckets have a lesser tendency to impart noise into the image.

Lenses for Travel Photography - Part V (Lens qualities and characteristics in purchase decisions)

This week in Part V of my seven part series about lenses for travel photography, I discuss what qualities and characteristics are important to consider when choosing lenses for travel. The series is primarily meant for SLR and DSLR camera users, who can attach a variety of lenses to their cameras to support their creativity, and suit the needs of their photographic opportunities.

Unfortunately for anyone purchasing lenses, there are a myriad of lens qualities, specifications, and characteristics which should be considered. Even if you’ll be purchasing nothing but the absolute best quality pro lenses, you will be weighing choices and making compromises.

You’ll have to decide the relative importance of specifications and characteristics for you photography to make your lens choices. This article should help you familiarize yourself with what you need to consider, and why, when purchasing your lenses.

Lenses for travel photography - Part II (Important Specifications)

This week in Part II of my seven part series about lenses for travel photography, I’ll discuss important lens specifications you should keep in mind when purchasing or choosing lenses for your travel. The series is primarily meant for SLR and DSLR camera users who can attach a variety of lenses to their cameras to support their creativity, and suit the needs of their photographic opportunities.

Among the important lens characteristics you should understand are:

• Focusing and sharpness
• Largest aperture and for zoom lenses when applicable, the range of the largest aperture at the full range of the lens’ focal lengths
• Magnification
• Focal Length
• Special Features such as Vibration Reduction, Focus Limit Switches, Extra-low Dispersion (ED) elements, special lens coatings, and no lens extension
• Potential problems such as focus softness in corners, vignetting (light falloff), chromatic aberration, and distortion
  
  

Panorama Photography Part II

In Panorama Photography Part I, I discussed what panorama photographs are, and why they’re so appealing.

Now in Part II, I discuss techniques for taking photographs for panoramas created from multiple photographs, and stitched together into a single spectacular image.

There are three major rules of thumb to ensure your images can be successfully mated to make a panorama.

1. You need exposure consistency in your photographs to ensure colors match from photo to photo which make up your image. One of the most common problems in stitching photographs together is differences in the color of the sky, due to inconsistent exposures photo to photo.
2. You need to ensure there is enough information in adjacent photographs that they can be successfully “glued” together. This accomplished by photo overlap.
3. You need to eliminate image parallax so that there are no ghosts in your final image and that lines in the panorama are aligned and look normal.

Here are my major guidelines for taking photographs to use in creating multiple photo panoramas:

• Use a tripod to keep all your photos in the same horizontal plane.
• If your panorama contains parallel vertical or horizontal lines, such as when the panorama includes a fence or building facade it’s important that your lens’ pivot point, or entrance pupil (the optical center of the lens), not the camera, be located directly over the central axis of rotation of the panorama. It’s relatively easy to locate the entrance pupil of a prime, or zoom lens (each focal point). By rotating your camera/lens over the pivot point, the problem of parallax, where the photographer can’t align vertical and/or horizontal lines in pairs of photographs when stitched together disappears. Really Right Stuff, the manufacturer of my panorama head has an excellent tutorial about locating a lens’ pivot point to eliminate parallax. (Please note, that while Really Right Stuff continues to call the pivot point the “nodal point,” which is an incorrect use of terminology, their method of locating the pivot point is the best way I know of to quickly locate and set the pivot point.)
• You need to keep your exposure settings uniform throughout your images, so their brightness and color will mesh, photo to photo. You should scan the entire scene making note of the aperture and shutter speeds your camera is suggesting, then pick one pair of settings in the middle, or slightly darker to make sure any sky details are preserved and manually set it, so that the settings will remain the same for each photographic image used in the panorama.
• Amply overlap each of the images in your panorama. You wouldn’t have liked my photo of Monument Valley with a white bar in it because I failed to overlap each photo enough. I overlap by 30% each time. Some say 15% works just fine, but I prefer more. Increasing the amount of overlap helps reduce “flaring” that happens when the software is forced to use all of the image frame, including the corners which may show distortion depending on your lens choice.
• Look for movement in your overall scene. While movement in a scene can make it more interesting at times, too many or large blurry areas in your photos can ruin your final panorama. When overlapping images have items which don’t precisely match, you get a blur, which can ruin the shot. I try to take each of my multiple images quickly to avoid the problem of movement. By the way, I do realize that some movement is unavoidable. You just need to minimize it.
• Shooting with shorter focal length lenses more often than not introduces problems of lens distortion. When there is lens distortion the stitching between side by side images can be unnatural looking. Many wide angle lenses suffer from barrel distortion to varying degrees. You can avoid this problem merely by shooting with longer focal length lenses.
• You should also minimize the use of filters, to obtain exposure and white balance consistency between the photos which will make up the complete panorama. Polarizing filters, in particular, often darken the corners of your photographs. Depending on the angle of light to the filter they can create a significant variation in sky color from photo to photo in the panorama, preventing you from creating a combined image which looks as one. I never use polarizing filters when shooting panoramas. For that matter almost any filter can add some vignetting to your images, which interferes with good stitching and the final image, so I normally never use a filter on my lens other than the UV filter which I keep on all lenses to protect them.
• I normally turn off auto focus and preset my focus manually for the entire group of images which will comprise my final panorama photograph. Image size can change with focus shift. If that happens, it’s likely you’ll never be able to achieve a high quality alignment of your stitched photos which make up the overall panorama image.
• I manually set my white balance of my DSLR to eliminate color shift from photo to photo so they will seamlessly stitch together. This is especially important for landscapes showing substantial sky.

Good luck. Let me know if these guidelines help you put together your next panorama.