Shadows in flash pictures

Bring out what’s hiding in the shadows

Pictures taken indoors with on-camera-flash usually have dingy, dark backgrounds. There is little that can be done about the behavior of light. An object at twice the distance from the flash will get only a quarter as much light. That means it will be darker in the picture.

There is no need to live with that problem. Post-processing, just a little bit of adjustments, can substantially enhance such photos. That is what the Shadows slider in Photo Gallery can correct substantially. With some judicious use of the Hightlights slider, and maybe a bit of adjustments with the others, a flash photo can be made to look quite good.

Here are a couple of screen shots to illustrate what can be done with a flash picture.

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This is the oroginal photograph, just the way it came from the camera. It looks like what you expect from a flash picture, the objects close to the camera, the table and chairs here, are properly exposed, things farther away look progressively darker.

Next the picture with some enhancements.

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The Shadows slider was moved all the way to the right to make darker areas of the photo lighter. Sometimes such a drastic adjustment may turn out to be way too much, but for this picture it worked well. The Highlights slider is moved a little to the left to make the lightes areas a bit darker. The Contrast slider was also moved to the right jut a little bit to increase contrast.  Note how much lighter the far wall is, it looks almost normal they way you would see it.

Other photo editors have similar tools. Sometimes they have different names. In Picasa the Fill Light slider brings the details out of the shadows. The Shadows slider makes intermediate toned areas darker. Careful use and a little trial and error will help you get the best pictures out of your flash photos.

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© 2016 Ludwig Keck

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Photography makes news

photokina-logoThe great photo equipment show, Photokina, once again has introduced a lot of new photo gear.

C/net has a nice overview article about what is happening:

How camera makers are getting their design groove on

Pop Photo has a gallery of innovations at:

Photokina 2012: The Best New Gear

20120919_Leica_S_001_610x526Samsung-NX

 

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Enjoy the articles and start saving your pennies!

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© 2012 Ludwig Keck

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Aperture is not what it used to be

In the olden days, as they say – that’s way back last century, photographers were taught to stop down the lens for best sharpness and depth of field. With 35mm cameras that was modified a little – apertures no longer went all the way to f/64. LJK_3724-640Smallest apertures were only f/16 on some lenses as seen in my photo here of a fifty year old lens.

Still, stopping down remained a good rule. Lenses sported aperture scales with the f-numbers, distance scales that were pretty accurate, and depth-of-field marks, as seen here, that made the relationship between aperture and depth of field pretty clear. In the photo here, the lens is set to the hyper-focal distance for f/16, about 8 feet. You can tell that the scale shows that objects from 4 feet to infinity would be sharp.

That brings us to “sharp”. The “sharpness” of objects in a photograph are always dependent on a number of different things. The resolution capability of the recording medium being just one factor. How a photo is reproduced and viewed is another. What looks tack sharp in a small print might be unacceptably fuzzy in a wall-sized enlargement.

LJK_3720 (3872x2592)Film for a long time was a limiting item, especially as cameras moved to smaller formats. One big problem lurking in the background always was “diffraction”. Yes, camera lenses are diffraction limited optics at the smaller aperture sizes. The aperture is that “hole” through which the light reaches the recording medium, nowadays, the sensor.

The distance from that aperture to where the light bundle converges to a point for an infinitely far object on the other side, is called the “focal length”. The focal length divided by the diameter of the aperture is called the “f-number”. The light actually never “converges to a point”. This is where the laws of physics wag a big finger. Diffraction happens, it is the cantankerous, ornery, way of light bending slightly around corners instead of proceeding in a straight line. The smaller the light bundle, the more light won’t converge to a point. We will let the physicists worry about “Airy disks”, the point here is that light is smeared out and small detail becomes fuzzy, the larger the f-number, the worse it gets.

As digital cameras get ever smaller, this problem becomes more bothersome. The individual sensor elements, “pixels” to all of us, are already smaller that what the optics can resolve. As the aperture is set to a smaller hole, the “spread” of the light increases. So the minimum aperture for some camera lenses is limited. I have seen f/11 as the smallest aperture on some cameras. Smartphones, which have absolutely tiny sensors, go to the extreme: No stopping down of the lens. They work at full aperture all the time.

I ran an interesting experiment. file-sizes-NEFI mounted my camera firmly on a tripod a good distance from my subject. This subject was a barren tree some two hundred feet from the camera. I was careful to exclude any foreground. I turned off auto-focus and vibration reduction. Then I took a series of photos at apertures from the widest, f/5.6, to the smallest, my camera goes to f/36. The first indication of how image quality is affected can be seen from the file sizes of the images. The seven images were taken at f/5.6, f/8, f11, f/16, f/22, f/32, and f/36. I let the camera choose the shutter speed.

file-sizes-JPGNotice that file size gets larger, reaches a maximum for f/11, then declines. When the raw images were translated to JPG format (at 100% quality), the differences became even more noticeable. Photo file formats reduce the file size by eliminating repeating values. The simplest way to explain this is to say that when a pixel has the same value as the previous one, instead of recording that value, a “ditto” is recorded. So if three pixels have the same value, the file says effectively “three times xxx”. As a consequence photos with less detail produce smaller file sizes since there are fewer different values. This is a gross oversimplification, of course.

Can you tell the difference in the pictures? You sure can!

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Here are small cutouts from the images. These cutouts are from the JPG images since this is how most photos get distributed and viewed.

Here, in a larger view the extremes, the f/5.6 image, the f/11, and the f/36:

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I was far enough from the tree so that the small twigs were narrower in the image than the pixels of the camera sensor. The first couple of photos show improvement in the image as the lens aberrations decrease as the lens is stopped down. Then, after f/11 (third image in the top row, center image of the larger views) diffraction and some other effects take over.

The moral of this story is this: For best image quality, do not go to small apertures, large f-numbers.

For my camera the deterioration in this test starts at about f/11. This is a DX format Nikon D-60. For full-size sensor cameras, the sensors, and the pixel elements are larger thus the diffraction effects will be less. For smaller cameras, especially the point-and-shoot pocket cameras, image quality will decline starting at even larger apertures.

To give you an idea of the size of the areas shown above, here is the full image with the section indicated.

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Camera manufacturers either help out, or cover up, depending on your point of view. You don’t see aperture scales on lenses any more. Distance scales are only on professional lenses. Cameras are programmed to do the best they can, and this means working at the largest aperture possible, not the smallest one.

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© 2011 Ludwig Keck

A useful learning resource

The Internet offers many useful resources for improving your knowledge and skills in digital photography. One such site is the blog All Digital Photography with a great deal of information, both basic and advanced, written in clear and easy to understand language. The author of the blog is Geoff Ronalds who has decades of experience in photography and now shares tips and techniques and some superb photography. Geoff mostly works with Nikon equipment and also shares reviews and details about cameras, lenses and accessories.

Here are some sample posts from All Digital Photography:

You can find links to the most recent All Digital Photography blog posts in the sidebar on the right.

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There may be more detail in your photos than you think

Sometimes you may be happy with a photo – perhaps a flash photo of friends, or a photo of a bird against the sky, like here. Flash pictures often show the people in the front row just fine, but the ones in back are dark and hard to even recognize. hawk-E1Photos of back-lit subjects might make nice silhouettes but are a little too dark to show all the detail.

Cameras do a marvelous job of taking the work out of photography, but you can improve the photos more often than not after they come out of the camera.

Here is a photo of a hawk. The sun was high in the sky and what we see is the shaded side. Not a bad photo you might say – considering the luck in getting it.

You can see the red tail feathers and nice detail in the wings. The camera did a pretty good job.

The dark areas, almost black in this shot,  may contain more detail than is apparent when the photo is seen on a monitor or even printed as is.

Windows Live Photo Gallery makes it easy to improve your photos. Clicking Auto adjust lightened the dark areas a bit – it was a good improvement. hawk-E2

The manual adjustments can make it even better.

Photo Gallery, in the Adjust exposure panel, has four sliders and also two histogram controls.

Brightness affects the whole photo and makes it either lighter or darker. The Contrast control can make the dark areas lighter and the light areas darker or vice versa.

The Shadows control only affects the darker areas, it can lighten them or make them even darker.

The Highlights control works similarly but affects the lighter areas.

For this photo I set the Shadows slider almost fully to the right to lighten the dark, the shadow, areas.

The histogram shows the distribution of the pixels from full black on the left to full white on the right. The vertical scale shows the relative number of pixels of that shade. Note that in this photo of a hawk against a blue sky there are two humps or curves. The low, spread out curve on the left shows the pixels of the hawk, the big spike is the blue sky.

There are two sliders below the histogram. The left one lets you set the black level. Slide it to the right and every pixel that is to the left of the indicator will be set to black. The right slider lets you set the white level. Every pixel on the histogram that is to the right of the indicator will be set to full white. The nice thing is that once these settings are applied, the pixels between the slider settings will be spread out over the full range from black to white.

For this photo I moved the white level slider a ways to the left. There were no pixels there, so I did not turn any areas into chalk white. The effect was to spread the pixels out, lightening the photo and the sky.

There is no best setting for any of these controls, just play with them until you are happy with the results. I click Revert to original quite often to permit me to start all over.

Enhancing your photos is fun to do. It is even nice when your friends say that you take good photos.

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© 2011 Ludwig Keck