HDR and Exposure fusion ... 101

I started to write a response about a question on Facebook, and within no time I had written a little more than I'd hoped. Also, It had been a while since I'd written something up for the blog.

Here goes nothing.

Most Digital SLRs, and advance point and shoot cameras have an option to setup and take bracketing shots i.e. take 3 or more pictures of varying exposures values (EVs). You may ask me what EV is - http://en.wikipedia.org/wiki/Exposure_value. In short it dictates what part of your frame is exposed "right".

Now you may wonder what I mean when I say DSLRs not depicting the picture right... Despite the advancement in photographic equipment, the modern day camera is not as advanced as the human eye.

That is why most photographs do not do justice to the beauty of a place. Ever taken a photo of a subject under a tree on a bright sunny day? You focus on the sky, the subject appears dark; focus on the subject under the tree, the sky looks brighter than normal. That is where HDR (High dynamic range) or LDR (low dynamic range/exposure fusion) come in. Both techniques have been around for a while. All they need for the input is pictures with different exposure values.

My D60 you had to do it manually by changing up the shutter speed - a faster shutter speed would let in less light, thus showing the brightest parts of the frame correctly; a slower shutter speed would let in more light - over exposing the bright parts but depicting the shadows correctly.

Everything else has to remain constant; i.e. ISO, Exposure compensation, Aperture. (now that said, feel free to tweak those around for a more "artsy" effect.

Here are a few examples of auto-bracketed shots.

Normal Image
1/160
f/11

Underexposed Image 
1/640
f/11

Underexposed Image
1/320
f/11

Overexposed Image
1/80
f/11

Overexposed Image
1/40
f/11

Now, if you have bracketing in your camera, like my D300s, you should be fine. Just set it up and fire away in the burst mode.

If your camera does not allow you to take bracketing shots then keep everything else constant, use Aperture priority mode on your camera and take 3 shots changing the shutter speed. Halve the shutter speed to change 1 EV. Examine the images, more so the images that appear to have gone near white-out. Look at the details in the shadows in this picture. 

Again, since the shots are meant to be merged together, the subject must have little or no movement to achieve good results. Using a tripod only helps keep photos aligned, this is very important.

If you are happy with the shots, begin the post processing. There is a multitude of software available to merge photos into HDR/LDR - qtpfsgui, photoshop, cinepaint, gimp, photomatix. All of them do a fairly neat job and are pretty self explanatory. Most are available to try before you buy.

If your photo is important, don't click the regular photo - it'll be flat and bland. Instead take composite images and create one HDR that is evenly lit up.

All in all, there is a lot of post processing, much like the delight when processing films of yore.

Final Image - Blue Canyon

Click to view in Flickr

Quick Tip: If you use aperture priority the depth of field remains constant.

I only wish I knew this when I was at the Grand Canyon last year; but then, I guess it only means that I have to go there again. :D

Composition - A "viewpoint"

Composition of a photograph is highly underrated aspect of design.

With the advent of digital cameras, the importance of composition of a photograph has taken the back seat. Most photographers are eager to take the photograph just because they can preview within seconds.

In the days of the film camera, the photographs would be painstakingly taken peeking in the viewfinder to ensure the subject is covered correctly and completely - a single photograph would take anywhere between a few tenths of a second to a few minutes to compose. What was different back then? ... the exorbitant cost of film. Not to mention the number of pictures would be limited to 24/36, and the only way to see a photograph was to go to a processing lab get the film developed and printed.

With digital cameras, the dis-incentives were eliminated. Very often people have archives of digital photographs whose numbers run into 10s of thousands. The philosophy has become "have camera - will shoot".

So, what is composition? According to Wiki "... composition is the placement or arrangement of visual elements or ingredients in a work of art, as distinct from the subject of a work. It can also be thought of as the organization of the elements of art according to the principles of art. "


Composition has more to do with what's around the Subject of Interest than with the subject itself. Very often we see photographs with an "unwanted" element and subconsciously re-wire our brain to avoid making that mistake. This is the design of the photograph.

Some principles of sound design when it comes to composing photographs are depth of field, limited focus, balance, asymmetry, rule of thirds etc., to name a few. When some of these sound design principles are applied to photographs, the photo looks visually appealing. While these are guidelines, many a times, breaking the rules also helps bring out a visually striking image.

Apart from the usual principles, a good visual art conveys the message via "hotspots" (those are the little white squares in the bing.com photographs).  There is no particular order in which one tends to view the hotspots. To elaborate more, next time you view a photograph, observe where your eyes take you - those are the hotspots. It may be the beautiful green eyes of Steve McCurry's "Afghan Girl" then the torn veil she's wearing, followed by her hair.

They say a picture is worth a thousand words; it is the composition that communicates the story to the audience. Next time you click, think about what you want to bring out, what is your "viewpoint".

Introduction

Welcome dear photo enthusiast!!!

Most of you reading this already know me. For those who stumbled upon or dug this site out, thank you for stopping by.

As to who I am, my name is Sridhar, I also go by Sri or Dhara (depending on who's yelling at me :-)).

When I'm not clicking photos I'm working for my employer, a large IT services company.

I've been an avid amateur photographer since the days of the film auto-focus cameras. I've moved on to different cameras and leveled up every few years, seeking better features.

The only reason I've started out this blog is to collate my thoughts and experiences on photography. I've lately been inundated with requests from you, my dear friends. Requests ranging from "sell me that photograph" to suggest cameras, share tips on lenses and in general taking photographs that you'd consider memorable.

I've resolved to give some serious thought into the things that I now tend to do intuitively and end up taking some good photographs. I also want to share some examples, some tips that I come across, hear, tricks that I try out.

To help channel my thoughts, I'd request you to email/message/post some questions you have that you want answered. There may be things you already know, and just want to bounce an idea, or hear my viewpoint - go ahead and send those things as well. Maybe someone may benefit from it.

Looking forward to hearing from you!

Thank you

Sridhar