Perspective Distortion

When we look up at the facade of a building, we are used to seeing the higher parts smaller than the areas below. The camera sees it the same way. We don’t think anything is distorted. That’s just the way light – and perspective views – work.

When we see a photo of a whole building that shows similar narrowing at the top, it appears to us as distorted. Some call it the “falling-over building syndrome”. Such photos are just not very satisfying.

What can you do?

First, understand that perspective “distortion” is not caused by your lens, it comes from the geometry of the situation. Parts of the building closer to you look bigger, to you and your camera. Parts farther away or farther up will look smaller. This happens in proportion to the distances involved. A window, say on an upper floor might be twice as far from you as one that is close and at ground level. That upper window will look half the size. Reduce the distance proportion and the perspective will not be as exaggerated. Back off!

Here is the same hospital photographed from farther away. Still nowhere near perfect, but much better that the other photo. So, back off, and the perspective will be better. Back off more and it gets better still. But there is more that you can do.

Here is the trick to use:

Level your camera so that the sensor plane is parallel to the vertical plane of the building. Yes, that means that the horizon has to go smack through the center of the frame. Not the best for dynamic composition, but cropping can correct that.

Here is a photo with the camera essentially level. Note how the far building looks perfectly acceptable. Why is that? You might ask. If you looked at the geometry, you’d see that inside the camera the distance between the sensor and the “center” of the lens at the top or bottom part of the image is larger than the distance at the center. And so are the distances to the center and top part of the actual situation. They are in fact proportional, and that makes for the “perfect perspective correction”. You can draw out the light rays and the optical paths, but just try it to convince yourself that this is the approach for good building photography.

The photo as it was taken, full frame on the left. A cropped part on the right. If you don’t want to crop and have money to burn, buy a shift lens. To tell the truth, this post was inspired by a question asked over in Ask Ludwig, How does a tilt-shift lens correct perspective distortion?

Yes, you can make corrections in post-pocessing

Just about any photo editor offers a way to adjust perspective. Here is the second hospital photo with such correction applied using the ON1 Photo RAW editor.

I like to leave just a little bit of that distortion when making the corrections in post-processing. I think photos look just a little more natural that way. I did not crop the photo after the perspective adjustment to let you see how the image was squeezed together at the bottom (the editor lets the sides at the top fall out of the frame).

So there you have it. No more “building falling-over syndrome” – three ways to make the photo look real and professional: Back away from your subject, level the camera (horizon in the middle), and use the perspective adjustment tool in your editor.

.:. © 2022 Ludwig Keck

Our Bridge

Our Bridge in Peachtree Corners

Just four months ago I took some photos around “our bridge”. I shared some of these photos, but a number of them I just post-processed for the first time. So let’s just take a look.

What’dya know, the new WordPress editor does not seem to allow re-arranging the order of the images in a tiled gallery the old-fashioned way. Now each image is a “block” and re-arranging requires “walking the block” with the <> icons.

I could not even type here after a short break. Had to start with a new paragraph. That does not forbode well.

.:. © 2021 Ludwig Keck

Be Prepared!

Be Prepared!

That is not just the Scouting slogan, it is an apt admonition to photographers. For years I have preached that a camera should always be ready for action. That means when putting it into its pack, it should be set so it is ready for a quick grab of an interesting situation.

Of course, when that moment came this past week, my camera was nowhere near ready. I had put it away after some still life photography without so much as checking any settings.

And this is what happened when I needed it in a hurry:

Vultures in the Attic

My recommendation is to always set the camera to AUTO mode to allow rapid shooting when needed.

There is more to that. The exposure mode isn’t all that should be in the “ready for action” setting. Here is my list:

Ready For Action Settings

Exposure mode: AUTO or P mode

Focus mode: Auto, with either single point or multi-point focus.

Vibration reduction: ON

Metering: Center weighted or matrix. Spot metering is great, but in hurried situations can lead to errors.

Exposure compensation: Zero. This control does not reset when the camera is turned off on many makes, so be sure to set it back to zero before stowing the camera.

ISO sensitivity: My “normal” setting is 200, many prefer 100. But there is more!

Set the Auto ISO mode ON to allow the camera to find workable settings. The high limit should be set to maximum. But the minimum shutter speed should be a reasonable value. I like 1/125 sec.

It was that last setting that really got me in trouble with the vultures. For shooting still-life scenes I had set it to 1 second.

That first photo at the top shows what can happen. The camera used 1 second, f/8, at ISO 3600. One second is more than I can hand-hold, even with good vibration reduction.

I got the camera to 1/125s, f/4, and ISO 200. But failed to watch where the center focus mark wound up.

Some days are like that! Nice photo of that mailbox, isn’t it?

.:. © 2021 Ludwig Keck

Squash Blossom

Photographing squash blossoms

When you search for “squash blossom” Google will serve up a long collection of recipes for frying, stuffing, and preparing them in other ways.

Photographing them? Who would ever want to to that? Squash blossoms are fickle models. Not easy. Each blossom is open only once and then for just a few hours. The open early, before the daylight gets good enough for photography.

This was taken about eight in the morning. The EXIF says 2020:08:02 06:55:10-04:00, I keep my camera clock on EST.

An hour and a half later a bit of sunlight got through the trees.

Notice that the edges have started to curl up. The blossom does present a neat star-like appearance. (8:28 EST)

Another hour later, at 9:33 EST, the blossom has begun to look bedraggled.

Little creatures have discovered the offering. Not yet the bumble bees that are the main pollinators, just the local neighbors. This is a male blossom and it offers its pollen in the hopes that some of it gets carried over to a female blossom.

Data on the photo below: Focal length 90mm, f/11, distance 0.56 m, DOF= 20 mm Not that the depth of field isn’t enough to get the small flies into focus. The image is cropped. Full frame showed all of the  blossom.

One more hour and the show is over. At 10:32 the blossom has pretty much closed up and looks like it will fall off shortly.

There is more to my story. These blossoms are about 4 to 6 inch across and are also quite deep. That makes getting everything sharp a challenge. For my first photo all the way at the top, I used a lens at 120 mm focal length and f/8. This gave a depth of field of just 18 mm (0.7 inch) as reported in the EXIF data, my shooting distance was 0.79 m (31 inch).

Besides having to manage the DOF exposure poses another little problem. Yellow blossoms, especially these orange-yellow ones, will confuse the camera light meter.

The image on the left shows the photo on the camera. This demonstrates that “chimping”, reviewing the image on your camera, is a good thing. In this mode the histogram is displayed individually for the three colors. The red arrow (added afterwards, of course) shows that the red data has a peak bunched up to the right side, indicating clipping of red information. This can show as washed out detail. You can see the same information in the histogram on the ON1 Photo RAW editor display, on the right. The image of the blossom looks good on the screen, but the histogram says that some red data is clipped.

When I shoot yellow flowers I underexpose, for this photo by a whole stop. Here is the screen view of the ON1 editor for the underexposed photo.

Yes, the photo looks distinctly underexposed, but the histogram shows that I captured all the data. This allows me to make the best of this image in post-processing.

So, to recap. Squash blossoms are temperamental models, they are open for only a couple of hours early in the morning. Their size across and in depth makes depth of field tricky. Pick what you want sharp. Their bright color can fool the camera, underexposure is desirable.

When you see a bud looking like this, set your alarm!


.:. © 2020 Ludwig Keck

Georgia Winter

Winter in Georgia

Yes, we do get winter down here in Georgia. Sometimes we even get snow. Here is my story of “winter” in Georgia in 2020.

On February 3rd our first daffodil greeted the new year.

The next day three more blossoms joined the chorus singing to the coming of spring.

Alas, it wasn’t spring that came. It was a cold rain “event” that beat down the flowers two days later and reminded us all of the official season.

The daffodils are a hardy bunch and determined to do their job. By evening they stated to lift their blossoms back up. But then, surprise, on the following morning, February 8, at around 9:30 snow started falling. It had been 750 days, according to one of the Atlanta meteorologists, since the last snow fall in our area. And it wasn’t just a light dusting. We got the full deal! By eleven o’clock that morning about an inch of the white stuff covered the ground and our spring messengers.

Winter snow had come! Of course, hereabouts that’s to be enjoyed quickly. It doesn’t last very long. By five in the afternoon the melting was on its way.

By nine-thirty the next morning it was back to work for our persistent friends.

Our trumpeter of spring proudly stands tall and bright.

… And so do its friends.

Our daffodils, my iPhone (which captured all but one of these images), my shadow and I wish you a happy Valentine’s Day and a glorious spring time!

.:. © 2020 Ludwig Keck