Creating Hand-held HDRs

On my recent vacation, I took a bunch of bracketed exposures to turn into HDRs. Before this trip I only used a tripod for bracketing. This time around, however, I had to deal with hand-held bracketed shots. To make things a bit worse, these shots included foliage, which isn’t always stationary between shots. Picturenaut utterly failed to align these images. I tried Luminance HDR (qtpfsgui) for Windows 7 (64-bit), and it simply kept crashing. Then I tried Hugin, which too failed to do much. Besides, it was extremely confusing since it is a tool for stitching panoramas, with HDR and alignment being a part of the whole.

Finally, I found HDR Alignment Tool — a free Windows utility for aligning multiple images using manually selected control points. Following is a screenshot of what the tool looks like.

HDR Alignment Tool

There’s a selection of input files at the top, and the output preview in the bottom right corner. The “In”, “Out”, “1:1” and “Fit” buttons are zoom settings for either the source images all together, or for the output preview. “CP1” and “CP2” refer to the control points and allow centering on the chosen control point.

The default selection of control point locations and the resulting alignment aren’t great, so just relocate each of them manually and fine-tune the alignment by visually inspecting the sharpness of the output image near the chosen control point. It’s cumbersome, but it works pretty well. The tool also includes some lens correction features but I didn’t use them, instead making Capture NX2 apply lens correction while creating the source JPEGs. Oh, let me now get to the workflow, which is a bit involved since HDR Alignment Tool doesn’t work with TIFF or RAW files.

  1. Load each bracketed exposure in Capture NX2.
  2. Ensure that all exposure parameters (white-balance, etc.) are the same, apply any other pre-processing steps (lens distortion correction, in my case) and create JPEGs.
  3. Open the JPEGs in HDR Alignment Tool, carry out the alignments and save the aligned JPEGs. By default, the tool will append “Aligned” as a suffix to the file name for distinction.
  4. Open the “*Aligned.JPG” files in Picturenaut. Apply the desired Tonemapping. Save the tonemapped output as a 16-bit TIFF.
  5. Load the TIFF back in Capture NX2, apply post-processing (tilt, sharpening, colour adjustments, etc.) and finally save the HDR JPEG.

The following photo is one example of the manually aligned HDR that I created. Creating one HDR took me about 20 minutes, after I got all things sorted out. The bottomline, however, is that its best to avoid these acrobatics and directly shoot with a tripod if you’re intending to create HDRs. You never know when you might want to create an HDR, so the second thing to remember is to always carry a tripod where possible… or get a Sony NEX-5 😉

Terrace & Garden

Capturing Rain

A tutorial on how to shoot rainfall with a digital camera.

With the monsoons doing their usual thing and I having the luxury of a not-too-bad view of the rains, I had been itching to capture a shot of the rain in all its glory. Earlier this year I made a capture that brought out the rainy-ness in the scene but didn’t have any rain as such.

Online research about shooting the rains didn’t bring much enlightenment because there’s no “formula” for making rain shots. It all depends on what you want to portray. For me, that would be about the prominence of the falling streaks of rain. All I knew was that I had to shoot a somewhat low shutter speed for that.

This Sunday, there was a brief spell followed by a longer shower, and I jumped at the opportunity (you don’t keep your camera nicely packed and hidden in your closet, do you?). The only thing I knew was that I had to shoot at 1/60s in Shutter Priority (S) mode. All of the first spell went in experimentation with other settings and by the time I got the hang of it, the rainfall had thinned out. Thankfully, it returned even stronger, so I got a nice shot, but in case you only get a brief opportunity, here are my observations that might help, right after the photograph I got.

It Rains. It Pours

  • Mind Your Background: The streaks of rain are most visible when they capture the light of the sky and there’s a dark background to contrast them against. Foliage works as the best background, both due to its dark colour and because the trees look so different when they’re wet, thereby adding to the “feel” of the photograph. In most cases, if you can see the rain, so can the camera.
  • Don’t Use Cloudy WB: If you’re shooting RAW and you play with WB settings while developing, you’d notice that using Cloudy/Shade WB makes the rain streaks almost disappear. This is because the rain-drops are visible only because they’re reflecting the sky and Cloudy WB tends to flatten the sky colours. If you shoot JPEG, this is the make-or-break setting. I used Daylight/Sunny setting for the above shot.
  • Over-expose and Pull: There is not much dynamic range in a rainfall scene. To get a nicely contrasty and colourful photograph, expose to the right and then pull back the scene while developing (e.g. adjust your black point to the extent that you begin seeing some dark spots in the photo). The above shot was made at +2/3 EV over-exposure. This only works if you’re shooting RAW.
  • Mind the ISO: Some times, the scene may become so dark when it’s raining that the camera may not be able to give a good exposure at 1/60s, even with maximum aperture. Watch out for signs of this (e.g. if the aperture reading in your Nikon’s viewfinder says, “Lo”) and bump up the ISO. The above photo didn’t have this problem but some other shots required ISO-400 at max aperture (~ f/5.6).
  • What Aperture? The above shot is made at f/5.3 but I got decent shots up to f/11. Seems like aperture doesn’t make a huge difference.

So, go ahead and try creating your own rain streaks. If you find any of the above tips helpful or not helpful, do drop a me a comment.

Happy clicking!

Shooting in the Dark

Digital sensors have made a lot of progress on the light efficiency front. The Nikon D3s sensor, currently the most efficient sensor available, offers amazingly clean images at crazy high ISOs. Something that film shooters could only dream of. There is still some time, however, before a D3s calibre sensor makes it to consumer bodies. Meanwhile, it will help knowing the tips and tricks of shooting in the dark for the win.


Before proceeding further on the topic, I’d like to say that the best thing to do is simply not shoot in low light. Most low light situations can benefit hugely from an off-camera speedlight bounced from the ceiling or walls. This essentially involves placing a large external flash like the SB-600 somewhere out of your field of view (your camera’s hot shoe is also a good candidate) and pointing it toward the ceiling. You can now happily shoot at ISO 200 and enjoy good, clean images with soft pleasant lighting. The following shot of pizza toppings was made at f/5.6, ISO 400, 1/60s in ambient light provided by 2 11-watt CFLs. Without the flash, this shot would have had less tonality, more noise and perhaps motion blur (corresponding flash-less settings would be something like ISO 3200, 1/8s).


The other very important piece would be a lens that has a large aperture, i.e. at least f/2.8 or larger. The AF 50mm f/1.8 D Nikkor aka Nifty-Fifty is a good, inexpensive purchase. Beware, though, shooting at very wide apertures places a big ask on focus accuracy because the DoF at large apertures might become too thin to be workable. Auto-focus systems also tend to perform poorly in low light. One useful tip for shooting people with wide apertures is to try and focus on the near eye — eyes are easier for AF systems to lock on, and it gives a natural guide for the viewer of the photograph.

Despite having the best gear, you still might end up in situations where you can’t do anything but bump up the ISO and face the lack of light. That’s where some of the following techniques will help.

Taking the Photographs

1. Exposure vs. ISO

The first time I was faced with shooting in low light, the camera metered some terribly low shutter speed like 1/20s at ISO 640, which is tough to shoot with even in low light. I decided to under-expose by a stop at the same ISO to get up to 1/8s because I didn’t want to hit the limit of the ISO range at 1600. Higher ISO = More Noise, right? Yes, provided the exposure is comparable in both. Under-exposure results in even more noisy photos. My shots from the above-mentioned sequence were all wasted. Here’s a noisy, under-exposed shot. Do you want to guess what ISO the following shot was made at?


ISO 100! You can see the effect of -5 EV under-exposure on the noise even in this small version. It would print really horrible on 6″x4″ paper. When you have to choose between underexposing and bumping up the ISO to get to a desired shutter speed, always go for higher ISO. An underexposed, low ISO shot is almost always more noisy than a properly exposed high ISO shot. Here’s another shot where I chose to over-expose +2/3 EV even at ISO 1600, to allow good tonality and saturation. The result speaks for itself.

Tandoori Burra Champ

2. Auto-Focus

Another area that suffers badly in low-light is auto-focus. Most AF systems try to lock in on edges that they find under the focus points where the boundaries appear the sharpest. This turns out to be difficult in low light because the difference in light intensity between light and dark parts of an edge are reduced. Having a speedlight like the SB-600 helps here, because it projects a focusing grid on to the field of view (much like the red grid you might see in supermarket barcode readers). If you find your hardware failing, you could try some of these tricks:

  • Zoom-in; Focus; Zoom-out: This works if you have a zoom lens that’s not “varifocal“, i.e. its focus doesn’t change while zooming in and out. The trick is to zoom all the way in, acquire focus — either manually or automatically — and zoom out to the frame you want. Most of the modern SLR zoom lenses are parfocal. I know that the 18-200mm f/3.5-5.6 VR Nikkor works.
  • Focus and Recompose: Sometimes, we would like to focus on a subject that’s not contrasty enough for AF or manual focus to work. In this case, it might be helpful to focus on a more edgy object at roughly the same distance and recompose. The results are iffy, though. Also, if you are not able to verify exact focus through the camera view-finder, chances are that your photograph would pass on as fairly in focus, anyway.
  • Live View: Most new DSLRs now support Live View feature. Live View can help you a lot when trying to focus manually. Turn on Live View and zoom all the way in on the view. Since you’re zooming in on the image preview and not on the lens itself, this trick works even with non-parfocal lenses. I made the following shot using the same technique in fading daylight. The AF was being tricked too often by the bushes and rubble, and generally being unable to cope with the fast moving bird.

Li'l Birdie

3. People Shots with Slow Sync Flash

One of the most frustrating experiences in low-light shooting is blurry people shots. When your shutter speeds drop to levels below 1/20s, asking people to stand still also doesn’t help. You end up needing to try something else. You also can’t pop the on-board flash because

  1. it gets into people’s eyes (not a problem with ceiling bounce), and
  2. it doesn’t bring out the ambient light properly, leading to an unpleasant photograph.

Issue #2 can be solved by using the flash in “Slow Sync” mode. In this mode, the flash fires for a short time (1/60s) but the shutter stays open for as long as it would have opened without the flash. You can choose whether the flash fires in the beginning of the exposure (Front Curtain Sync) or toward the end (Rear Curtain Sync). Why would you use slow sync instead of just shooting without flash? Because it de-emphasises motion blur that occurs while the flash is not on and captures a sharp outline when the flash pops.

While shooting people in slow sync mode, Rear curtain sync works better than front curtain for two reasons. One, people don’t notice a snap until the flash goes off. In front curtain, they tend to think that the snap is done when the flash goes off and let go of their pose while the shutter is still open. This leading to blurry shots.

Secondly, rear curtain captures motion in the forward direction. You get to see the final position of a moving object most prominently, which is more natural than seeing the starting position of an object and seeing a blur in its later direction of movement.

While using slow-sync, just always remember to disable pre-flashes by using FV lock to determine exposure. You want your flash to fire exactly once, and toward the end of the exposure, to get people to instinctively comply with the slow shutter. You might also want to use an orange colour gel in front of your flash if you don’t want the people to appear blue while shooting in incandescent light. Here’s a 1/8s full-on action shot of my friend strumming on the guitar, taken using this technique. If you look carefully, you could reveal a lot more motion blur than what is apparent in first glance. That’s the rear sync advantage!

Ambar and the Guitar

4. Camera Stability

One of the easy ways of success in low light is to be able to use slow shutter speed, at least for relatively still subjects. The problem here is that slow speed results in camera shake. It is, therefore, important to learn how to have a stable grip on the camera. I myself, took a very long time getting this right. Part of the reason is that people talk about this aspect very infrequently on forums. Part of it is that you only get the information in bits and pieces. I’d invite you to go through this excellent blog post on how to make a “human tripod”. Supporting the camera: holding with your hands.

One of the techniques I often apply when faced with camera shake is to burst a series of shots. Chances are that one of those shots will be sharp. It frequently happens to be the first in the series and I find bursting for more than 2 seconds to be a waste. The following is a 1/4s shot made using a Canon PowerShot A630 P&S in burst mode.

More Nikon D80 Switches

That’s it for this article. It still talks about shooting at high ISO and it is inevitable that you’ll get noise in such shots. In the next post, I’ll talk about development techniques that would help you reduce the apparent noise, beyond just pushing the NR slider all the way up. Oh yeah, you’re shooting RAW, aren’t you? 😉

Take Two

I, Photographer

This isn’t my first time writing a photography blog. I started one, almost 3 years ago and wrote a few posts regarding technique and gear. It was probably too early to start writing, though, and the blog fell off the edge when my hosting plan expired and I didn’t renew it. This time, it will hopefully stay.

Photography is, for me, a new way to experience things. It’s about delving deep into the visual characteristics of the environment around me — shapes, contours, colours, location, the light that I’m seeing by. This ability to observe also allows me to interact with inanimate objects in a new way. I can play with things by giving them different looks through the medium of photography. It may seem trivial at first, but for those who have to live by themselves for some length of time, it’s a relaxing and challenging pursuit that keeps the mind occupied from devilish or plain depressive thoughts.

Photography is also quite rewarding. After spending huge amounts of money on acquiring the right gear, learning the right skills, taking time out to visit the right places and finally making the right image, when you hold a 12″x18″ print in your hands, the sense of satisfaction is as good as from any other accomplishment. Those photographs are not mere memories, they are testimony to the fact that you had a uniquely personal interaction with an environment or an object.

Through this blog, I hope to share my observations and notes with anyone who might be interested as I work on developing myself as a better photographer, and share the small joys I may get out of the photographs that I make along the way.

Click away!