Daily Archives: February 21, 2012

Alignment – When it all goes wrong


Something I have brought up in the past about over-shooting a scene –  taking too many exposures –  popped up last week in one of my images. I was shooting the ocean sunset and shot 6 exposures using AEB + EC (Auto Exposure Bracketing – Exposure Compensation) It’s a quick way to get 6 (usually 5 because one can be a duplicate) exposures of a scene without having to do much figuring.
When I got home I threw the 6 images into Photomatix Pro 4.1 and selected my usual alignment “Match Features”. I use this because often I have some complex objects in the foreground and I need them aligned as perfectly as possible.
I merged the image and what I got was this “widescreen” image. and you can see a misaligned  handrail on the right side.
What? I didn’t shoot widescreen! Going back and looking at the images I could see what the problem was as we can see here looking at the six exposures

The first two exposures are so under-exposed they have very little detail left in them for the software to find edges to align. (You can also have this probelm on an too over-exposed image that is totally blown out)
So the simple answer could have been to just eliminate those two exposures from the merge, they may not have had enough information – as is the case when people over-shoot a scene- to even be worthwhile putting in the mix.
So I did that and still using “Match Features” for the alignment mode, Photomatix perfectly aligned the image and did not crop off any part of the image
OK, great. But the truth is, the image did not have the color range I wanted especially in the dusk sky. So I went back and merged all 6 images again, this time choosing “Match Horizontal and Vertical shifts”. Because there was, even in the lowest two exposures a clear line for the horizon, this would be a good choice.
Using this method, I got a perfect alignment AND the full range of color and luminosity (and DR) that I wanted for the image.
Just another example that shows us that using the same setting all the time, even if we really like that setting, isn’t always the right choice. And that experimentation may be the best thing to do to achieve your final goal.
One final thing to note was that the image WITHOUT the two darkest exposures was actually darker than the one with all 6 images. (Both used the same tone mapping) this is because the software needed to bring some information down into the shadow area and it brought some of the midtones with it.
Hope that helps

Reader Featured HDR Image – Joseph B

Todays’ Reader HDR Image comes from our buddy Joseph Bowman up in Oregon

Here’s what Joe had to say about his image



     Haystack Rock – Cannon Beach, Oregon 

     Camera Info:
     6mp Canon EOS Digital Rebel (300D)
     Lens: 18-55mm kit lens
          – Hey, who says you need thousands of dollars worth of equipment to make an image you love!
     Manual, f/22, iso 100, @ 18mm
     6 shot HDR @ ss 1/5, 1/10, 1/20, 1/60, .4, & 1 second
     HDR Processing & Post Processing
     Photomatix Pro
     Photoshop Elements 7
Here’s the image: (Click to enlarge)
     About the Image:
     This shot was taken a little before sunset, at around 5:20 p.m. (my exif data is off as I haven’t reset the camera time). I put my camera on a tripod, set it as close to the ground as it would go, and I placed it at the edge of the small rock and tide pool in order to add some foreground interest. I set my camera to manual, figured out what my base exposure was, then adjusted for my six shots. I wasn’t sure if I needed all six or just three but figured it was better to have them and not need them. Plus, even with the camera set to iso 100, I was concerned about the potential noise that would pop up if Photomatix had to try to pull too much information out of the image. My Digital Rebel is HORRIBLE for noise!
   The image was processed in Photomatix Pro and “cooked to taste.” After Photomatix, I took the image into Photoshop Elements where I cloned out some of the lens flare at camera right and I cloned out the people, which was the most intensive part of the whole process – but overall not too bad thanks to the texture of the rock being so forgiving. I also burned some of the clouds to give the sky more drama, and I adjusted the vibrance and saturation levels to add pop to the sky and rock. The one thing I wish for this image is that I could have gotten a little wider than the 18mm in order to get more of the sun into the image.
Beautiful job Joe. Ahhh Cannon beach , when I lived for a short time in Portland, Cannon Beach was my favorite place to go on the weekends. Never got many good shots since it rained everytime I went. ( rainy Season) but I love the town and certainly love Haystack Rock.
Great job on the image. I love how you included some foreground interest, many would have just had the bare sand in front.
I know what you mean about the lens, 10-20mm lenses on a cropped Canon are the bomb for shots like this. The one suggestion I would make as far as your choice of aperture, I know you went to f/22 for maximum DOF. However you can get some softnesss in images from diffraction after a certain aperture depending on Sensor size. For a crop sensor like the one on Rebel XT you shouldn’t go past f/11 unless you really have to. With f/11 and a subject distance of 5 feet, which the seaweed appears to be. You would still have a DOF from 2.5′ to infinity even at f/11 AND a sharper image. If you had a subject say 1.5 feet, yeah you may have to push  it to f/22 for Max DOF.
Good job getting low! And this was a tough image to edit because of the ocean mist. You really pullled it together
Great job Joe on a beautiuful image from one of my favorite places on earth.