Nature Notes

June 18, 2009

15 causes of poor images and how to fix them

Filed under: Photography Tips,Processing Tips — Tags: , , — Harold Stiver @ 7:00 am

1. Poor Focusing Blur
2. Camera Shake Blur
3. Subject motion blur
4. Too much Contrast
5. Vignetting
6. Crooked Horizon
7. Lens Distortion
8. Lens Flare
9. Chromatic aberration
10. Red eyes
11. Noise
12. Color correction needed
13. Incorrect Exposure
14. Sensor Dust
15. Correct Sharpening needed

1. Poor Focusing Blur

Poor Focus Blur

Poor Focus Blur

In the image above the sharpest focus is on the foreground grass rather than subjects behind.

The majority of images that aren’t sharp are caused by you or your camera. The wrong area was chosen for the area of focus. You can improve by becoming more aware and meticulous in your point of focus. It is often useful to reduce the number of focusing points to one. While this is often the center point, you need to occasionally use an outer point for best results. Know how to change it on the fly.

Since it is difficult to educate your camera, it can be better to make some decisions yourself. This involves getting out of the program mode.

2. Camera Shake Blur

Camera Shake Blur

Camera Shake Blur

Looking at the above image, you will see areas were there is a ghost or duplicate. This is typical of camera shake, the shutter speed was not sufficient to freeze the motion caused by hand holding the camera while shooting.

One of the easiest solutions is to use a tripod. You can also change the settings to increase the shutter speed by increasing the ISO or decreasing the Depth of Field or f-stop.

Another good practice is to learn how to han hold shoot with a minimum of shake. Lock the elbow of the hand holding the camera against the body, keep your legs spread and press the shutter very softly.

3. Subject motion blur

Subject Motion Blur

Subject Motion Blur

The back wing of this female Red-winged Blackbird is blurred because I didn’t have a fast enough shutter speed. The common “solution” to this situation is to say that you meant to do it, to show a sense of motion. Baloney!! While there are occasions when a blur looks great, most of the time an image looks much better without it.

This usually happens when you are shooting a relatively still subject who suddenly moves. Since these movements properly captured can be some of the best, especially for nature photographers, you need to anticipate them to get them. This means set your camera to a much faster speed than is needed with your still subject, and you will be ready for that action shot.

4. Too much Contrast

Too much Contrast

Too much Contrast

Although greatly improved in the last few years, cameras can only handle so much Dynamic Range, that range of exposure from the darkest to the lightest. This commonly happens on bright days when the areas in shadow lose detail or become “blocked”.

The solution has been to avoid shooting in these conditions or to expose for that part of the image that is important.

A new solution is using HDR (High Dynamic Range) processing. This involves multiple exposures of the same subject processed by software such as Photomatix to bring out details at both ends of the exposure.

5. Vignetting

Vignetting

Vignetting

Vignetting is where the brightness of an image falls off towards its edges. It is not always a problem, in fact it can often be an artistic effect which helps highlight the central area, and is often deliberately used in things like wedding photography.

It can be caused by filters and holders, as well as lens hoods, or by the nature of the lens design. Full frame cameras such as the Canon 5D tend to be more prone to it.

You can change your depth of field to eliminate or lesson the problem. You can also eliminate it in processing, photoshop’s raw conversion has an excellent adjustment available to fix the problem, and this can be set as a default for the camera should you want to.

6. Crooked Horizon

Crooked Horizon

Crooked Horizon

A very common problem in landscape shots, where the tripod may be set up on uneven or soft ground.

There are bubble level devices which are part of some tripod heads or which can be added to them. This may be a good idea if you shoot a lot of landscape.

However there is an easy fix in photoshop using the ruler tool. Here is a tutorial that was posted previously on this.

10 Seconds for a Perfectly Level Horizon

7. Lens Distortion

Lens Distortion

Lens Distortion

To a greater or lesser degree, lens will show a slant of lines that should be straight. The problem becomes worse the closer you are to the subject.

If you do a lot of architectural photography, you may want to invest in a Tilt/Shift lens, which is designed to deal with this problem.

You can also deal with it in processing. Following is a Photoshop tutorial dealing with

Fixing Perspective

8. Lens Flare

Lens Flare

Lens Flare CC License from orangeacid

Lens flare occurs when light entering the lens bounces off of the various elements. Sometimes creative photographers use it for effect but often it is an unwanted addition.

It is caused when the sun or other bright light shines down the barrel of the lens. As well as watching where you are shooting, you can also give yourself more leeway by using a lens hood.

An unwanted lens flare can often not be fixed in processing. If it is minor, you can increase the image contrast to regain what was washed out, and you can attempt to clone out stronger portions.

9. Chromatic aberration

Chromatic abberation

Chromatic aberration

Chromatic aberration occurs when the lens fails to focus all of the colors to the same point. This is more of a problem with poorer quality lens. In the example above, the “lens” was a sighting scope held against a Point and Shoot camera.

This can be reduced by increasing the focal length where possible. In can be corrected in processing by selecting the portion of the image where it occurs and desaturated for the troublesome color.

10. Red eyes

Red eye CC Licence from noelzialee

Red eye CC Licence from noelzialee

Red eye occurs when a flash is used resulting in a reflection of light off the back structure of the eye. There is also a similar effect called steely eye where some animals eyes have a look of blue steel caused by reflected flash.

The fix in processing is a fairly simple one. Select the portion of the eye effected and desaturate for red and then darken. Some editing programs have a special menu command to accomplish this.

11. Noise

Noise

Noise

Noise in a photograph is the appearance of faint color speckles in an image, often green or orange in color. There are various causes like the heat generated by the camera sensor or the amplification of the background electrical. Smaller sensor cameras like many Point and Shoots are more prone to this problem.

DSLR cameras have come a long way in reducing the noise  from their cameras. Five years ago, shooting at 800ISO from my Canon body generated noise in an image that I would need to deal with. In my latest Canon body this problem area is more like ISO3200.

There are effective ways of dealing with Noise in processing an image. Most RAW converters have a Noise reduction function, and, in fact, in the image above, the default setting in the RAW conversion eliminated the noise. Photoshop also has tools to eliminate noise included. Additionally their are programs which do the job (and often for free).  A couple of the most popular are Noise Ninja and Neat Image.

12. Color correction needed

Color Correction needed

Color Correction needed

Unless directed, your camera makes the decision as to the White Balance in your image, and if you wish to change the result, you need to Color Correct it.

The easiest way to Color Correct an image is in the RAW conversion where you have the oppurtunity to adjust the White Balance. In the above image, I found the color of the snow was too blue and needed correction.

There are a couple of tutorials on the subject of Color Correction which you may find useful

A simple Color Correction

Quick and Dirty Cast Correction

13. Incorrect Exposure

Incorrect Exposure CC Licence by lkhlasulamal

Incorrect Exposure CC Licence by lkhlasulamal

One of the problems faced by new photographers is getting a proper exposure. There is a temptation to let the camera decide on the exposure but this often results in under or over exposure.

The ideal is to get in right before processing. You need to learn to adjust the exposure based on the individual scene and this takes experience. You can  make adjustments after viewing the image in the view screen and re-shoot. The slang term for this is “chimping”. You also need to learn your camera’s metering modes and apply what is best. For example bird photography is often improved by spot metering.

Processing can improve exposure problems primarily by using the Level and Curve commands. I have posted four tutoria;s on adjustment which may be useful.

Recovering Blown Highlights

Using a Luminosity Mask

Understanding Curves

Processing a Backlit Subject

14. Sensor Dust

Sensor dust

Sensor dust

This Laughing Gull was taken at the end of a two week trip to Cape Hatteras and by that time I had accumulated a couple of stubborn globs of dust on my camera body sensor. Sensor dust is a problem of modern digital cameras and one that most photographers have had to deal with.

The first step is prevention. Dust enters when lenses are changes. Use a lot of care when you change that you try to do it in as dust free a situation as possible. Use a blower to give the sensor a squirt of air on a regular basis. Finally, don’t forget to clean your lens caps, probably the main source of dust.

If you do get dust on your sensor that a blower won’t remove you will need to have it cleaned. You can do it yourself (Google: Sensor cleaning) or have a camera dealer do it for you.

Cleaning a dust specked image is a fairly easy matter with the dust or clone tools. Lightroom will allow you to batch this process to do multiple images at once, a function not available at Photoshop.

15. Correct Sharpening needed

Sharpened Image

Sharpened Image

Its been said that every image from a digital camera needs some sharpening. I think that is close to being true even if you only have the sharpening that is done automatically in camera.

However, it is usually the case that only a part of your image needs sharpening, and you want to do it in a way that leaves no artifacts, that is, no halos, jaggies, bands or noise.

There is probably no type of processing that has so many different methods, and every photographer swears theirs is the best. So here is a tutorial on my way of sharpening. And by the way, I swear it is the best.

Selective Shapening


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4 Comments »

  1. […] more:  15 causes of poor images and how to fix them | Nature Notes This entry was written by ThomP, posted on June 18, 2009 at 6:00 am, filed under general and […]

    Pingback by 15 causes of poor images and how to fix them | Nature Notes - Images and Photograph in natural.. — June 18, 2009 @ 10:44 am

  2. Very useful Harold, excellent photo quality examples and well explained. Thanks a lot.

    Comment by Roberto — January 17, 2011 @ 5:36 am

  3. Love every one of these tips! Thanks so much for sharing!

    Comment by Laura Dienzo — April 4, 2011 @ 5:48 pm

  4. Thanks Laura,

    Your website is excellent!!

    Comment by Harold — April 7, 2011 @ 9:53 pm

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