I recently blogged about my winter project of shooting agaves locally.  In prepping for this shoot, I wanted to make sure the entire plant was in focus, and I knew using my depth of field table, that it was essentially impossible using my 24-105/4 lens:

• The example I’ll use in this post was shot from a distance of ~2 feet at a focal length of 47mm and aperture of f/10; using my Canon 30D, my total depth of field is 0.2 feet.  That isn’t nearly enough to get the entire agave in focus.

To circumvent this problem, I wanted to take multiple exposures at different planes of focus then blend them in Photoshop to produce an image that is entirely in focus.  The problem I was having is that by doing it manually, I couldn’t find a self-feathering method to make the blend look “clean”.  Fortunately Photoshop CS4 has an image blending feature that mostly automates the process for you.  I’ll describe my experience using one of my agaves as an example.

The first step was to take the shots.  I composed the shot like I normally would, and took one or two tests to make sure the amount of fill flash looked about right.  To get the proper diffusion, I taped a piece of white printer paper to my 430EX and underexposed by ~ -1.5 stops EV.  After the shot looked “right”, I took three exposures, each one at a different plane of focus:

While these three images do not look much different, you can see subtle differences; by looking at the main floret protuding from the plant, you can see that it is increasingly out of focus as you scroll through the images.

Once I got home, I converted the RAW files in a way that looked good to my eye; when you are working with multiple exposures, make sure to ‘synchronize’ all of your adjustments so all your shots look the same!  This is easy to do in ACR.  Then, I opened the files in Photoshop CS4.  The first step is to load the files into a stack and align them.  You can do this by going to File–>Scripts–>Load Files into Stack

Select the option “Add Open Files”, and check the box that says, “Attempt to Automatically Align Source Images”.  This will load your base images into the script, and will align the images, because even if you shot from a tripod (using mirror lock-up) there will be some slight differences between the images.

Once the script runs, you will want to select all three layers on the layers palette and go to Edit–>Auto-Blend Layers…

Select the option to stack the images and make sure the “Seamless Tones and Colors” box is checked.  This will produce a perfectly feathered and mostly blended image using your base images.  At this point, I suggest you inspect the image at 100% to make sure it is indeed perfectly blended.  On some images, the script has done a great job, and on others I’ve had to reload some images as separate layers and mask off the “in focus” part.

Even if it doesn’t work perfectly, this method will get you most of the way there.  If you like the result, you can flatten the image and edit as you normally would.

Agave attenuata, blended and converted to black and white

There are times you may not necessarily need to use this method; for instance, sometimes simply stopping down to f/16 or f/22 may get you the depth of field you need, but remember, as you stop down, you are losing resolution.  Thus, shooting at a wider aperture and blending exposures can be beneficial if you plan on printing the image.

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A few posts ago, I talked about a great day at the San Diego Zoo’s Wild Animal Park.  Its a fantastic place to visit, but with large crowds and harsh midday light, photographing animals can be difficult.  Maybe I’m just in an abstract mood lately, but I found a lot of interesting patterns in bird feathers, etc.  One particular shot I liked was of a Chilean Flamingo (Phoenicopterus chilensis), which I’ve honestly never found to be a photogenic bird (at least not in captivity).

By underexposing the image by 1 2/3 stops, I was able to largely blacken the background, and introduce some contrast to the contours of the feathers.  That allowed me to boost the vibrance and saturation a bit, giving an eye-popping splash of color to the Flamingo I’ve always struggled with.

Chilean Flamingo, detail

Not only have I been in an abstract mood lately, I’ve also been in a black and white mood.  Thus, I converted this to black and white as well, really cranking the red channel up to make it contrasty.

Black and White

I like both of these a lot, for different reasons?  Do you have a favorite?  I’d love to hear about it in the comments!

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As a photographer, or even a nature lover, you’ve probably stood staring at a wide vista wondering how you can possibly do that view justice in your photographs.  Maybe you’ve even wanted to be able to print that picture large to give a room in your home the same feel as actually standing there.  Have you ever thought about taking multiple images of a scene and stitching them together into a panorama?

Shooting “panos” has become more popular in the last few years with the advent of point-and-shoot digital cameras that stitch the image in-camera for you, but if you want to shoot a panorama with your SLR, there are some things to consider.  First, and this should be a no-brainer, pick something interesting to shoot.  It may look impressive as is, but if you pick out something with substance, it will look even better!

So you’ve got your vista picked out.  Now what?  In my experience, the key to producing quality panoramas is making sure your tripod is level.  If this is the case, you will have much better luck at the stitching process.  I have used two different methods to level my gear; the first is via a 2-stop process that’s super cheap.

My tripod does not have a built-in bubble level, so I start by removing the head, and placing a bubble level (~$3 at Ace Hardware) on the tripod.  Tinker with the lengths of your tripod legs until you level the tripod.  Now, put your head back on, and you’ll see that it can rotate on a level base.

By removing the head and using a spirit bubble level, I can make sure my tripod head is rotating on a level base.

The second, and more recent, method I’ve used is by putting a leveling base on my tripod.  I use the Manfrotto 438 leveling base, but other companies like Acratech also make them.  They’re more expensive than my first method, but they’re way faster and you don’t have to fiddle with your tripod legs.  To level your camera on your tripod use a hot shoe level like the Jobu Designs Dubble Bubble level.

My tripod head can be leveled easily and quickly using the Manfrotto 438 leveling base.

After leveling my tripod head, I level my camera on the tripod using a hotshoe level.

OK, now you’re level.  The rest of the pano practically shoots itself.  I usually work from left to right, making sure to overlap my images by anywhere from ~1/3-1/2.  This makes for a lot of images (many of mine are 12-15 images) but you’re almost sure to get a better stitch at the computer.

A couple of other things to consider before we discuss stitching:

• To shoot vertical or horizontal…that is the question.  In stitching, you’re almost guaranteed to lose a little of the top and bottom of your images because the software will correct for barrel distortion.  Because of this, I almost always shoot my panos in a vertical orientation.  That way I’m left with an image that is a little more proportional, instead of something VERY long and skinny!
• Just like with any shot, sharpness matters.  When I shoot panoramas, I almost always use a cable release and set my camera to shoot in mirror lock-up mode.  This reduces any possible vibration, hopefully ensuring a better stitch.
• Do not change your focus or any camera settings while shooting your panorama.  However, consider bracketing your shots.  That way you have more to work with at the computer, and you can even consider making an HDR panorama (let’s save that for another blog post, please).
• I haven’t addressed the problem of parallax yet.  Unless you are rotating on the nodal point of your lens (or using a pano slider), you will have parallax issues if anything in your pano is closer than ~10-15 feet.  The cheap solution is to make sure trees, rocks, etc are further than ~10-15 feet from my camera, and that seems to work to subdue parallax.  The obvious downside to my method is that you’re constrained as to your compositional choices.

So, now you’ve got your image files, and you’re back at the computer.  Can you simply align them in Photoshop manually, then crop the canvas down to its final size?  I think this works for most people ~1% of the time (I’ve managed to do it once, and I’m 99% sure it was dumb luck).  Every other time, the barrel distortion, as well as other factors, will necessitate the use of software to help you stitch your images together.

Dumb luck. I stitched this 4-image pano together manually--I've never gotten it to work since.

For stitching panoramas, I use the software package Panorama Factory.  I like it because it has a fully automatic mode, which should work really well if you leveled your rig properly and provided enough overlap between images.  Alternatively, Panorama Factory allows for various levels of manual stitching, letting you define stitching points, and for the occasional difficult to stitch image, I like that mode a lot as well.  If you are interested in shooing HDR panoramas, Panorama Factory will stitch different sets of exposure identically so they overlay perfectly.  I have to admit that I’ve tried this once, and it didn’t work quite as smoothly as I’d like.  I’ve found that using the auto-align feature in Photoshop CS4 works well before blending images.

So, that’s basically it.  This tutorial was meant to get you taking beautiful panoramas using a minimal amount of equipment.  I hope you enjoyed it.  Feel free to add to the comment section if there’s anything I missed, or needs corrected.  Hope you can find this useful!

An 11-image panorama of the Ritter Range, Sierra Nevada, California

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I’ve decided to make Fridays the day for Marginalia; noting things from the week.  For this week:

• This weekend (Aug 15/16) is the U.S. National Parks free weekend!  Get out there and visit a national park for free.  For more info, click here.
• Last week, I mentioned that Jay Goodrich guest blogged on Darwin Wiggett’s blog.  In return, Darwin and Samantha Chrysanthou guest blogged for Jay, again on the acceptable uses of Photoshop in photography.  A very thoughtful commentary, you should check out.
• Speaking of Samantha, she recently blogged on the usefulness of social networking in photography.  So did Guy Tal.  So did a recent thread on Naturescapes.net.  The verdict?  Seems like resounding inconclusiveness.  I’m not sure if its worth it, but you can follow me on Twitter, Facebook, and Myspace.  In fact, please do.

That’s all I know this week.  See you where the light is.

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Although its been popular for a while, I’ve recently begun working with multiple images to produce high dynamic range (HDR) photographs.  What is HDR?  HDR is a series of methods developed to produce a high dynamic range image from a set of photographs taken with a range of exposures.  There are multiple methods for producing an HDR image, from blending multiple shots in Photoshop to processing a single RAW image multiple times and blending those in Photoshop to using HDR software like Photomatix.

My goal here isn’t to tell you how to make an HDR photograph, because there are already fantastic tutorials out there, written by people much more talented than I am.  Probably the most complete tutorial was written by Royce Howland over at Naturescapes.net.

Because you can probably already produce an HDR image on your own, I want to share some nuances of the process I’ve learned to make your images look more realistic.  These aren’t new techniques, and I didn’t come up with all of them myself–to give credit where credit is due, Royce Howland, E.J. Peiker and Paul Stoczylas are the masters.  I’m but a student.

Part I: Getting rid of the halo

Photomatix is a powerful program and has a very user-friendly interface that pretty much does the work of producing an HDR image for you.  Because there are no monitors that can visualize that kind of dynamic range in an image, you must first tone map the image before being able to display it.  You have two options: Details Enhancer (DE) and Tone Compressor (TC).  DE is the default, and although it lacks some mid-tone contrast, it looks a lot better than a straight TC image which is way over-saturated.

The problem with tone mapping with only one algorithm is that you’re limited by each one’s constraints.  For instance, halos are a big constraint of the DE algorithm:

Towers of the Virgin, Zion National Park, Utah, June 2009

This shot looks pretty good, but you notice at the junction between the sky and the cliffs that the sky turns noticeably light blue–that’s because I only tone mapped with the DE algorithm.

This halo can be especially problematic in images where you have trees against the sky.  In this series of posts, I’ll cover a couple of methods I’ve learned to make the HDR image look a little more  realistic and squelch that halo!

Stay tuned…

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