PERFECTING THE PANORAMIC

It’s getting easier to make panoramics with today’s cameras. Some will actually do the stitching together for you without the need for software. But unless you take control of the process, you may be selling yourself short on results.

Here is a checklist you can follow in preparation for shooting your panoramic. It may look a little daunting, but it will become old hat with a little practice:



• Arrive Early   In order to get through this checklist, you’ll need the extra setup time before the light changes!
• Use a Tripod   A panoramic is comprised of a series of adjacent photographs stitched together in software to form a single wide-angle image. In the stitching process, the software does its best to match adjacent images seamlessly, but there is usually a bit of twisting required to match them perfectly. This requires cropping the final panoramic. Unless the individual images are shot with the camera absolutely level, the twisting and subsequent cropping may get to the point where much of the scene is lost.
• Level the Tripod and Camera  I have a bubble level on the base of my tripod which I use to get the legs levelled up first. I also use a bubble level that slips onto the camera’s hot shoe, which I use to do fine levelling adjustments. The reason for using both is that uneven legs may give me the impression that I have a level camera at one position, using the hot shoe level. But as I pan, I would likely see the level drift off centre. Once you have tweaked both the legs and the pan/tilt head, try panning through the intended range of your panoramic to ensure you have optimized both.
• Set the Camera to Manual (M) mode   Imagine you’re shooting a panoramic made up of photos that have dramatically different light content. In any mode but Manual, each photo would be exposed differently because the light metering system built into your camera tries to set the exposure automatically to an average 18% grey level. In this scenario, the panoramic wouldn’t look right because the inherently darker scenes would be forced to look lighter compared to the others, resulting in a patchy-looking result. Sure, you could try matching the exposures in software before stitching, but it’s easier to get it right in the camera. I pan the entire scene first, using the digital meter to set a shutter speed/aperture combination that averages a normal exposure. As a result, some shots will be over-exposed slightly, others under. As long as the histograms for all photos don’t show any clipping at the black or white points, you’re OK.

  

  The camera's digital light meter. Zero is optimal exposure.

  

 

 

 

 

 

 

•  Set the Camera ISO setting to a fixed value  Some cameras have Auto ISO setting. Per the last point about exposure, ensure you choose a fixed value (eg. 200) rather than Auto.
• Set the Camera to manual focus  Most SLR lenses have a switch allowing you to disengage the motor that automatically focuses your lens before you take a shot. For panoramics, set it to manual focus (MF). The reason for this is that as you pan to take each of the shots, the camera may refocus on something close in or far away, especially if there’s an object in one of the shots that is prominent. That could result in uneven focus across the panoramic. Pick one focus setting that works for the whole panoramic and leave it there.
• Take the Camera out of Auto White Balance  Similar to the argument in the last two points above, you don’t want the camera to change the colour balance as you pan because of changing content. Choose one of the presets instead of Auto. For instance, if shooting on an overcast day, use the Cloudy Bright setting. If shooting an indoor scene under fluorescent lights, use the Fluorescent setting. If you have access to a photo editing program that allows white balance adjustment, don’t worry about what preset you choose, because you can correct all the shots by the same amount if the preset you chose results in wonky colour.
• Overlap the Photos  Panoramic software uses artificial intelligence to look for similarities between adjacent shots then join those features seamlessly. In order to provide those reference points, you need to provide overlap in content between adjacent shots. I typically overlap by 25%. If I start my panoramic on the left end then take subsequent shots by panning left to right, this means that my second photo contains the rightmost 25% of the first photo. I’ve made marks on my tripod head that tell me how far to pan before taking the next shot while allowing 25% overlap. I have marks for both landscape format and portrait formats. But, of course, those marks only work for one focal length, which brings me to the next point….
• Use a “Normal” focal length  For a consumer digital SLR with an APS-C sensor, normal focal length is about 33mm. Anything shorter is considered wide angle. The wider you go, the more barrel or pincushion distortion will be introduced. This may make it harder for the stitching software to match the photos without twisting the photos to counter this effect. The more twisting, the more cropping of the final panoramic you’re likely to have to do. Of course, you could use a longer focal length without this concern, but remember that depth of field reduces with focal length.  I use a 35mm prime lens for panoramics, adapted from an old film camera.
• Choose the Right Content  I like shooting sky panoramics. I found out the hard way that sometimes the stitching software will not work properly with some content – particularly soft images with few hard edges. Some sunset clouds fit that description. Sometimes, it helps to include some hard edge detail (like treetops) to assist in the stitching. You can always crop it out later.

• Choose the Right Software  I find that the ‘premier’ photo editing package gives too many choices when creating panoramics. You have to try them all to find out which one works best, but my experience is that I generally don’t like any of the results. On the other hand, a cheap and cheerful package sometimes works better and with less fuss. I particularly like ArcSoft’s Panorama Maker, which came bundled free with my point-and-shoot camera.

 

 

3 overlapping images stitched together, before cropping. Note how the software has to distort the images to make them match up.



As you can see, the process of shooting panoramics like a pro is very manual. If you’re shooting a scene with moving clouds, set up marks on your tripod so you can rapidly make all your shots before the clouds change position and shape. And finally, resist the temptation to use more than 3 or 4 shots in a panoramic, because you’ll end up with a long, skinny picture sitting in the middle of your print that will look silly.

Depth of Field: Choosing the Right Focus Point

Most of the time, when we want to get everything in our shot in focus from our feet out to infinity, the tendency is to dial in as high an aperture number, or f/stop, as possible. In doing so, we hope to increase the depth of field in the image, or the range from our near in-focus point to our distant in-focus point.

But there are two other parameters that have a dramatic effect on depth of field: focus point and focal length of the lens. Two rules of thumb for increasing depth of field are

·         Manually focus as far away as you can from your subject while still keeping them in focus at the aperture you are using, and

·         Use as short a focal length as you can to compose the shot.

Take the second point. We’ve all seen wildlife and sports shots that are taken with a very long focal length lens. The subject is very sharp while the background and foreground are very much out of focus (shallow depth of field). So, conversely, using a short focal length (or wide angle setting) results in a deeper depth of field.

Choosing the focus point, however, is probably the most critical parameter in achieving the shot you want. The first point above implies that the further away from the camera that you focus, eventually you will have everything in focus from a point close to the camera out to the horizon (infinity). To put a label on it, when this happens, you are focused at the hyperfocal distance. This term is mostly of interest to landscape photographers but the point is that, counter-intuitively, we need to focus beyond our subject to get it and the background appearing sharp.

The best graphical demonstration of this is the Online Depth of Field Calculator at www.dofmaster.com. Choose your camera model, focal length, aperture and subject distance. Assuming you focus on your subject, the calculator tells you the near focus and distant focus points. The difference between these is the depth of field.

Hyperfocal distance is also illustrated. If you focused at this distance, everything would be in focus from the distance shown in the illustration out to the horizon. Note that sometimes hyperfocal distance won’t get your subject in focus because the near focus limit is further out than your subject. In this case, you would have to use a higher f/number, shorten your focal length or resign yourself to not having the horizon in perfect focus.

The following images were shot using highly sophisticated dollar store markers at 5 foot intervals. The closest was 5 feet from the camera’s sensor. The camera was a Canon Digital Rebel using a fixed focal length of 35mm in all examples. Each image has been cropped from the originals.

In the first image, aperture was set to f/22 and focus was manually set to the calculated hyperfocal distance of 9.5 feet (just in front of the second marker).  Notice that the 5 foot marker is still in focus, as well as the tree top a couple of  hundred feet away (See insert). This is because the near focus limit is calculated to be 4.7 feet. (Note that the insert looks a little soft because the sensor resolution is starting to come into play.)

 

The second image was also at f/22, but the camera was now focused at our subject, the 5 foot marker. The calculator tells us that if we focus at 5 feet rather than the hyperfocal distance, our focus range now covers 3.3 feet to 7.2 feet. So our depth of field has now decreased from infinite to 3.9 feet just by focusing at 5 feet rather than 9.5 feet from the camera. Note that the markers at 10 feet and beyond are a little softer, and the tree top is no longer in focus (slightly softer).

 

At f/10, our next image was focused at the calculated hyperfocal distance of 21.1 feet (just past the lowest 'lollipop'). The near focus limit is calculated at 10.5 feet, and indeed the second marker at 10 feet is very slightly soft. The tree top, while not perfectly sharp, is close to being in focus. I chalk this discrepancy up to difficulty in getting the focus exactly at 21.1 feet. Note that our subject at 5 feet is badly out of focus, so f/10 is clearly not a good choice if we want focus from 5 feet to the horizon.

 

 

Still at f/10 in the last image, the subject at 5 feet was once again our focus point. Calculated near and far focus limits are 4.1 feet and 6.5 feet, giving a depth of field of only 2.4 feet.

 

The conclusion? Decide whether you want to shoot like a landscape photographer or whether a little bit of in-focus background will suffice for your shot. Even if you don’t use hyperfocal distance, the calculator will help you choose a manual focus point beyond your subject that will keep it in focus but still give you a decent background focus.