High Dynamic Range HDR Images

HDR photography is all the rage now. I know how to make them and I like them but while I can see how they are a huge step forward in photography both technically and creatively I am still not convinced it isn’t a fad. I will certainly say that I far prefer HDR images that have a more natural look to them than the Photomatix-ified comic book looking tone-mapped HDRs that seem to have captured the most attention.

Here’s are a couple of HDR images I did the other night. I like how the water swirls around and smears the lines of the support posts in this image:¬† HDR image 1 of the Oceanside Pier area.

Oceanside Pier HDR 1

Oceanside Pier HDR 1

I like this one since it has both an ethereal and a realistic quality to it: HDR image 2 of the Oceanside Pier Area.

Oceanside Pier HDR 2

Oceanside Pier HDR 2

These were made with 5 separate exposures each ranging from -2 to +2 stops exposed. I converted them from 32 bit to 16 bit images using either exposure and gamma (HDR 1) or local adaption (HDR 2) conversion processes, did a little sharpening and that’s it, really. I’m still experimenting with this technique; I use the HDR function built-in to Photoshop right now.

Ideally Canon would issue a firmware update that allows me to make 5 or even 7 auto exposure bracketing images to more fully exploit this technique (my 40D only has a 3 image AEB function now).

Panorama Photography

Panorama Basics

Panorama images have become a favorite photographic technique for me. I really enjoy making huge panoramic, sweeping images from multiple exposures. Panorama photography is easy to do; you don’t need a special camera and in some cases you don’t even need any particular special technique.

For example, this panorama of Death Valley’s Racetrack Playa was created by taking 5 individual exposures and using Photoshop’s built-in panorama function.

Death Valley Racetrack Playa Grandstand

This image Рas many of mine are Рwas hand-held. This panorama of Panamint Valley was created with 12 or 14 images  (6 or 7 across 2 rows) and is a huge file.

Death Valley Panamint Valley

For a basic panorama you should carefully set up your shot and have about 20% to 25% overlap from image to image. I always hold the camera in portrait orientation for horizontally-oriented panos and in landscape orientation for vertical panos.

You should set the camera’s exposure mode to Aperture Priority to ensure that the depth of field does not change from image to image and you should also remove the polarizer filter if you have one attached to the front of the lens. Aperture priority means you select an “f-stop” (the lens aperture) and the camera will select a shutter speed appropriate for the conditions. All of this assures that each image’s exposure will be similar and will look natural when they are all stitched together.

Advanced Panorama Techniques

When capturing images of objects or scenery far away relatively speaking, a handheld approach provides good results. But, when a panorama of close-in objects or a scene is desired, the proper technique and the proper equipment is required. The workflow with the camera is the same, but rotating the camera around it’s nodal point and eliminating parallax is vital.

Another approach is to use a robot, such as the Gigapan product line. The cost differential between a full-blown Really Right Stuff manual set up and a Gigapan set up is minimal, with the advantage to RRS that no batteries are required and the advantage to Gigapan that the process is automated.

Stitching Software

Many software options exist (Mac OS X search); the Gigapan system comes with it’s own software, Photoshop CS3 and above has a panorama mode included. I have used Kekus Software’s PTMac software as well as their Calico product. Most of these are a lot more “hands off” and designed for ease of use. They have a lot of internal smarts and can do a top-notch job of merging the individual images into a gorgeous panorama image.

PTMac, however, is fundamentally different from these others; it is designed to give you the most control possible in selecting overlapping control points from adjacent images and save those control points as a file which can be used for subsequent panoramas. Why would you want to do that? Well, the most important application is if you want to do an HDR panorama. You can do it two ways; you create individual HDR images for each panorama segment and then stitch them together, OR you can stitch each set of image exposure sets and then HDR the 3, 5, 7 or more panoramas into an HDR image. But to do that, you must stitch all the exposure sets using the same control points; otherwise you’ll get alignment and registration problems when you try to build the HDR image.

Final Image

This panorama of Mission San Luis Rey de Francia in Oceanside, CA was shot at night and used 3 rows of 5 images each. I have several others similar to this at my Southern California gallery at my photo gallery (Alan R Zeleznikar Photography).

California Oceanside San Luis Rey Mission

Night Sky Photography

Night sky photography requires some specific equipment and techniques.

  • You must have a tripod because whether you are shooting digital or film you will be exposing the image for very long periods (in photography a long period is pretty much anything over half a second).
  • You must have a camera that is able to have long exposure times.
  • You must be able to control the lens opening (the “f-stop” or “aperture”).
  • You must have a wide-angle setting for the focal length.
  • You must have a very high ISO film or be able to set the ISO on your digital camera to something like 800 or 1600.
  • (Optional) If your camera has a built-in automatic noise processing function you must be able to turn it off

The reason for all of this is to capture as much light as possible without having the stars turn into fuzzy blobs. With the settings I’ve described above you’ll get a lot of light into the camera and still have pin-point stars. Anything over 30 seconds or if you zoom in to telephoto you’ll start to see star streaks/blobs since the Earth is spinning the whole time, making the star field traverse across the sky.

This night sky image of the stars above Anza Borrego Desert State Park was taken with my Canon 40D with my EF 24 – 105 mm f/4 L IS USM lens. The lens was set to f5, the exposure was 20 seconds (the 40D has a maximum exposure time of 30 seconds, exposure times higher than that must be executed in Bulb mode). The f-stop is slightly smaller than full open in order to reduce/remove distortions caused by the very edge of the lens optics. An f/5.0 setting “chops off” the light at the very edge and sharpens the image at the expense of losing a little bit of light.

Night sky image with star streaks Anza Borrego

If you want to take those super-cool pictures that show the stars as long circular streaks then you are looking at very long exposures – 30 minutes or an hour or even more. In that case you can adjust some of the other parameters so that the overall amount of light entering the camera is less per second. The stars themselves are bright points and get detected OK anyway.

This image of streaking stars above Death Valley is about 30 minutes long at f5 with an ISO of 400. A higher ISO in this case records too much background light in the sky.

Night sky long exposure star trails Death valley

Exposures like this are where film cameras still shine since in many upper-end digital cameras long exposures will trigger the camera’s built-in noise reduction algorithm which requires as long a time to process as the exposure, so a 30 second exposure requires 30 seconds more of processing, so an hour exposure is a two hour total process. You can get twice as many exposures (or be done in half the time) than with a digital camera in those circumstances. If you can turn off the in-camera noise processing you should consider doing so. Photoshop CS3 RAW processing has a noise reduction feature included as way to reduce or eliminate noise artifacts from long exposure images.

I have several photo galleries featuring images of California, the US Southwest, Europe (Germany, Austria and Italy) and Asia (Japan, Taiwan, Hong Kong and China) at my Photoshelter galleries site.