The Portland Metro Photographic News

Original PMPN Articles Intended To Provide Some Insights and Information to Make Photographers' Lives A Little Easier

Each generation of DSLR cameras comes with improved image sensors that promise reduction in the electronic noise (perceived as grain) at each ISO setting.  The race to minimize "noise" has, in part, been fueled by photographers' requirement that image quality must be equal to or better than traditional film to gain the respect of the professional and fine art communities.  As the first ten years of the 21st century come to a close, it's a good time to reflect on the advancements camera manufacturers have made in the film grain challenge.

PMPN has gathered three generations of DSLRs to compare their "noise" characteristics.  The cameras used included are shown below.  Together they cover most of the sensor improvements released between the years 2000 to 2009.

 
Left to right: Canon D30 circa 2000, Nikon D200 circa 2006, Nikon D3s circa 2009

There is NO attempt to compare Canon to Nikon.  The intent is to use these three cameras to visualize the "noise" improvements made by the industry over the course of a decade.  At every generational step, EACH camera manufacturer's sensor showed similar "noise" characteristics to its competitors. (In this article Canon would be at a considerable comparative disadvantage since the D30 represents the first generation of this decade's DSLRs.  Today's high end Canon cameras would compare very favorably to the Nikon D3s used in this sampling.)  Consequently, for the purpose of this article, it's best to think of these three cameras as Generation 1, Generation 2 and Generation 3 of 21st century sensor technology development.

Scene used for collecting sample ISO images from 3 generations of sensor development

The one-time, high-end Kodak camera and imaging supplies shown above comprised the basic scene for the pictures used in this ISO sampling. The area shown in the RED box was enlarged in each sample image to more easily see the "noise" present at each ISO setting.  The cameras were all tripod mounted and use these settings:

• largest (finest) JPEG file setting available
• sRGB color space
• Auto white balance
• Aperture setting  f/6.3
• Tripod mounted using self-timer
• Focus point: the word "Kodak" near the front lens element
• Used only the standard ISO settings available on each camera
• No post-processing image manipulation, sharpening, etc. - These are the images as they come from each camera.
• No in-camera "noise reduction" was used

The goal was to produce final sample images for this article that reflected the image quality that would be seen in typically and "reasonably" sized digital prints (in the 8"x10" range). When evaluating these particular images "noise" is most easily seen in the smooth black areas around the lens and in the background seen in the upper right-hand corner.

ISO 200

   
Left to right: Generation 1 (Canon D30), Generation 2 (Nikon D200)

 
Above: Generation 3 (NikonD3s)

At an ISO setting of 200, there is only a slight visual difference between Generation 1 and the Generation 2 and 3.  But at print sizes up to 8"x10", the difference would be barely noticeable.

ISO 400

  
Left to right: Generation 1 (Canon D30), Generation 2 (Nikon D200)

 
Above: Generation 3 (NikonD3s) 

At ISO 400, the generational "noise" difference between sensors starts to become noticeable. It was this objectionable "grain" in the first DSLRs of the decade that raised the eyebrows of photographers whose work required the use of ISO 400 transparency and negative films in their professional assignments.  The stigma of these first high ISO settings with the first generation of sensors has been difficult to erase.

ISO 800

  
Left to right: Generation 1 (Canon D30), Generation 2 (Nikon D200)

Above: Generation 3 (NikonD3s)

At ISO 800, grain has definitely become a quality issue for professional photographers using Generation 1 sensors.  Even Generation 2 sensor-equipped cameras are showing noticeable "noise" in the black areas of the lens and background.

ISO 1600

  
Left to right: Generation 1 (Canon D30), Generation 2 (Nikon D200)

 
Above: Generation 3 (NikonD3s)

Photographers were eager to exploit the promise of extreme ISO settings that digital photography offered.  But Generations 1 and 2 sensors yielded less that favorable results at very high ISO settings.  It wasn't until the advent of the latest sensor technology that ISO 1600 and above became viable quality options for the working professional and fine art photographer.  Generation 3 sensors are showing no more noise/grain at 1600 ISO than would be expected from the traditional film practice of "push processing".

ISO 3200, 6400, 12800

Generation 3 (Nikon D3s)

ISO 1600 is the highest "standard" ISO setting on the Canon D30 and Nikon D200 used in this comparison. But to complete the visual sampling of Generation 3 sensors, the images below were taken using the remaining high, standard ISO settings of the Nikon D3s.  (The same image taken at ISO 200 with the 3Ds and can be seen as the top left photo in the display below -- as a visual reference.)

  
Left to right: ISO 200 for visual comparative reference (Nikon 3Ds), ISO 3200 (Nikon 3Ds)

   
Left to right: ISO 6400 (Nikon 3Ds), ISO 12800 (Nikon 3Ds)

Even at these extreme ISOs, the "noise" is not objectionable.  This "noise" is no more objectionable than "grain" that is experienced when "pushing" traditional film.  Visually, and in terms of "noise", the latest generation of sensors appear to be equal to or better than the "grain" quality of traditional film that has been "pushed" to equivalent ISOs.

Shown below is a scanned image of a full-frame, 10"x7" black and white print made from traditional Kodak Tri-X film rated at ISO 1200.  The film was "push" processed in Kodak HC-110 developing solution and printed on Kodak Polycontrast paper.

© Hubbard Camera LLC

 
© Hubbard Camera LLC

The grain that is visible in the enlarged image above is what traditional, film-based photographers would have considered normal and acceptable for black and white ISO 400 film pushed to ISO 1200.  But, when compared to PMPN's informal study of Generation 3 sensor results at similar ISO settings, this image is no better.

Reviewing and seeing the accomplishments in digital sensor technology over the past 10 years, it seems only fair to say to camera manufacturers, "You've come a long way, baby."  Each milestone in DSLR sensor ISO research has provided significant improvements in image quality that, today, is worthy of critical comparison to its 35mm film cousins.  These improvements certainly beg the question: "What's next?"

Whether Generation 3 image quality is at the point that individual photographers will consider it to be "on par" with traditional film is, in large part, subjective.  This debate is as personal as the traditional photographic discussions about the virtues of Kodak Plus-X versus Tri-X film or Agfa versus Ilford papers.  What isn't subjective is the quality improvement that 10 years of digital sensor research and development has brought to photography.  Each photographer will have to access these achievements and the value they add to their photography in making the final call.

There will be some PMPN readers who will receive their first DSLR this Christmas season.  For you and others who take up the challenge of shooting Christmas light, PMPN has prepared this basic tutorial to take some of the guess work and mystery out of shooting these works of seasonal arts and craft.

Millions of pictures will be taken this holiday season to memorialize the creative light displays of dedicated (and occasionally fanatical) artists of the Christmas bulb. Situations like these often result in disappointing pictures due to the unusual light conditions.

PMPN's list of equipment and settings for this discussion includes:

• Tripod: to stabilize camera during long exposures
• DSLR with 18mm to 200mm lens and exposure compensation capability
• ISO: 100 to minimize digital noise and maximize image detail
• White Balance was set at the Incandescent/tungsten selection
  
• Shooting Mode: Aperture priority to control depth of field.

Lighting display pictures present some interesting photographic problems.

The picture above is typical of the results in these unique lighting environments. Although the scene has been captured, the highlights have been overexposed and contain no details. The result is the visual "fusing" together of the individual lights that make up the display.

The picture at right is an enlarged section of the first image above. Notice the lights that provide the detail in Santa and the snowman have merged to produce an over-exposed mass of white.

The metering problem is created by the amount of dark area in the overall scene, and the extreme intensity of the display lights (the scene's high dynamic range). The camera's metering is attempting to provide an exposure setting that will produce an overall exposure value that is equivalent to 18% gray. In most cases, the amount of dark area is greater than the light areas and has the greatest influence on the camera's metering system. As a result, the camera determines settings that over-expose the individual display lights.

The goal should be to determine an exposure that distinguishes the individual lights that make up the scene. (Just as our eyes perceive them.)

 
Exposing for the lights reveals the details in the display
(ISO 100, 1 second, f/8, aperture priority mode, -2 stops of exposure compensation applied)

The picture above has been exposed for the display lights. Notice that the individual lights and their colors are now distinguishable. The strings of lights have also provided enough illumination to allow some of the house details to be seen and add structure to the image.

 Close up of properly exposed Santa and Frosty at left.
(ISO 100, 1 second, f/8, aperture priority mode, -2 stops of exposure compensation applied)

Now the individual lights and their colors are visible to give the image the details in the displays and colors of the season. We elected to intentionally under-expose the image by 2 stops using the camera's exposure compensation control. How did we settle on 2 stops?

I used a combination of camera feedback:

• 1. The camera's preview screen. Watching the preview image, we were able to see the results of each trial exposure and "see" the impact of exposure compensation changes. We were looking for the setting where the individual display lights became recognizable.
• 
  
• 2. The camera's histogram. By watching the camera's histogram display and ensuring that the highlight densities were not pushed too far to the right border of the histogram (over exposed).

Here are two more examples from the house next door:

 
Again, the individual lights are indistinguishable and detail is lost
(ISO 100, 4 seconds, f/8, aperture priority mode)

Exposing for the lights reveals the details in the display
(ISO 100, 1 second, f/8, aperture priority mode, -2 stops of exposure compensation applied)

Notice anything? The exposures for this example are exactly the same as the first example. The point is that there is much similarity between displays. The exposure settings determined for one display become an excellent starting point for others.

A couple of final thoughts:

• There are many ways of taking these lighting display pictures. Other photographers might have elected to use a high ISO setting (in the range of 1,000 to 1,600 for example). This is a very workable suggestion when you don't have the luxury of using a tripod and must hand-hold your camera. These higher ISO settings will provide faster shutter speeds. At the same time, just be aware that "noise" will become more apparent as the ISO values increase.  So, use a tripod and a lower ISO setting when your goal is to capture as much detail and as little digital "noise" as possible.
• Snow is your friend. Unfortunately, in our area, snow seldom falls during the holiday season. If you are lucky enough to shoot holiday displays with snow on the ground, you will be the beneficiary of additional fill light that is being reflected from the snow. This provides more structure to the picture and, obviously, more of the appropriate holiday mood.
• It is possible to go overboard in the quest to make the individual lights distinguishable. We prefer to find an exposure that still provides some detail in the house and/or landscape to give the picture more structure. The picture below suffers from too much exposure compensation and a lack of structure:

Over compensating for the lights reveals the details in the display but loses the structure provided by the house.
(ISO 100, 1 second, f/8, aperture priority mode, -3 stops of exposure compensation applied)

by Tom Hubbard, December 8, 2009

PMPN’s recent article, “Converting Your Family’s Collection of Negatives & Slides to Digital Files”, ended with the promise of publishing and article dedicated to the topic of preserving digital image files.

This article focuses on the most popular optical media currently being used to back up and store image files – CD-Rs and DVD-Rs.  As it turns out, these two media provide the longest life expectancies of all the types of CDs and DVDs on the market.  No attempt will be made to explain the technology and mechanics of how CDs and DVDs work.  Instead, this story is only concerned with the proper “care and feeding” of CD-Rs and DVD-Rs to enhance their life expectancies.

I’ve long been aware that CDs and DVDs had their archival limitations.  What I didn't know was how critical the recording device, the brand of media and the storage/handling of UNRECORDED disks are to the integrity of data and the life of a CD or DVD.  Neither was I aware of how fragile and susceptible these plastic data libraries are to damage.  If you thought, like me, that CDs and DVDs were more durable than an original film negative, you’re in for a surprise.  Depending on your practices for purchasing, recording and storing CDs and DVDs, today’s optical disks may have a shorter life span than original film and slides.

Several authoritative organizations having the responsibility or necessity to track and monitor the technical aspects of optical data storage were used in PMPN’s research.  These sources included:

• National Institute of Standards and Technology (NIST)
• Council on Library and Information Resources (CLIR)
• Eastman Kodak
• International Standards Organization (ISO)
• Optical Disk Archive Test Committee (ODAT)
• The Library of Congress
• Thexlab.com
• Ancestry.com (a website for amateur and professional genealogists)

The question that typically starts a CD or DVD conversation is, “How long will the image files on my CD last?”  Let's begin by tackling this subject with the clear warning that this question opens the flood gates to other, and equally important, considerations.

Under what are considered to be normal storage/care conditions, manufacturers ESTIMATE the life expectancy customers should expect from the optical storage media shown below. That is, the length of time in years that recorded data will be readable.

First Some Definitions:

• CD-R – the most familiar and most often used CD used for storing digital image files – can only be "written to" once
• CD-RW – a CD that can be "written to" repeatedly
• DVD-R – the most often used DVD for recording digital – can only be "written to" once
• DVD-RW – a re-writable DVD

Unrecorded Shelf Life: (Yes, Virginia, there is an expiration date for CDs and DVDs.)

• CD-R and CD-RW – 5 to 10 years
• DVDs - Unspecified

Recorded life span: (length of time data should be readable after recording)

• CD-R – 50 to 200 years
• CD-RW – 20 to 100 years
• DVD-R – 30 to 100 years
• DVD-RW – 30 years

Maximum Number of Rewrites: (for re-writable CDs and DVDs)

• CD-RW – 1,000
• DVD-RW – 1,000

The less optimistic news is:

“Only a few independent laboratories have conducted accelerated life tests for such media. Those conducted by the National Institute of Standards (NIST) and the Library of Congress (LoC) may provide more realistic estimates of optical media longevity:

• An unpublished report of the recently-terminated "NIST/LoC Optical Media Longevity Study" of recordable optical media stated that, after 11 months of testing:
  • Virtually all CD-Rs tested indicated an estimated life expectancy beyond 15 years.
  • Only 47 percent of the recordable DVDs tested indicated an estimated life expectancy beyond 15 years. Some had a predicted life expectancy as short as 1.9 years.
• A 2004 NIST study found wide variations in the stability of different bands and compositions of writable optical media. While some samples proved to be very stable and could be expected to "ensure data availability for several tens of years," others showed significant data loss after only 100 hours of rapid aging. [1] We interpret "several tens of years" to mean roughly 30 years.” – from thexlab.com

The truth about life expectancy is probably somewhere in the middle for the typical photographer.  The point is the life of a CD or DVD is finite and quite possibly not as long as an original film negative or slide.  This realization means, we cannot simply copy our files to a CD or DVD, put it away and expect to always be able to access the files.  Like a developed negative or slide, a CD or DVD begins to deteriorate as soon as the “burning” process ends.

Two other often overlooked facts:

1. DVD’s life expectancies are estimated to be less than CDs.  The increased storage capacity of a DVD is compelling, but the data may not last as long as with CDs.
2. The music CD that you purchase has a much longer life expectancy because the data “bumps” are permanently pressed into the CD as it is being manufactured.

What are these other considerations impacting the life of a CD or DVD?

You were warned that several other factors must be considered when a photographer evaluates his or her optical storage practices or when determining the archival nature of storing digital files on CDs or DVDs.

Because these variables are not included in manufacturing tests, failure by the user to account for any of these factors further REDUCES the archival nature of data stored on a CD or DVD.

To be fair to manufacturers, I have researched several packages of CD-Rs and DVDs and several (but not all) of the precautions shown below can be found on the product packaging.  However, some of the product care and handling tips require a small magnifying glass to read.  Besides, who reads the fine print.

1. Use a high-quality CD or DVD recording device

The integrity and life of recorded files on a CD or DVD are, in large part, determined by the quality of your computers CD writer.  Spend your money here.  The quality and accuracy of the laser system defines the caliber of the recorded data.

2. CD or DVD quality matters

There is a difference in the quality of CDs and DVDs.  The quality difference is seldom a function of the reflective dyes or raw materials used.  The quality differences are primarily attributed to manufacturing processes and standards.  Price is often the most visible indicator of this difference. You’ll get exactly what you pay for.

Some manufacturers offer Gold CD-Rs.  These manufacturers’ estimate the life of this media at 300 years.  Because the 24 karat gold reflective layer on these CD-Rs is more resistant to oxidation, corrosion and the effects of UV light, it’s reasonable to assume these disks will better survive environmental exposure.  Whether or not the estimated life expectancy is correct, we’ll know in 90 to 300 years.

3. The color of the CD matters little. 

The color of a CD or DVD is derived from the dye and the metallic coating which reflects through it.  Since the dyes and metallic coatings can be used in various combinations, color is not a reliable yardstick for determining the quality of a CD or DVD.

4. There is a shelf life to unrecorded CDs and DVDs.

The effects of time and environment impact a CD or DVD before they are used.  The industry estimates the shelf life of new CDs or DVDs to be between 5 and 10 years.  So, just because you found a great price on a box of 500 CDs, it isn’t a good deal if you can’t use the CDs within 5 years.  Since there is no way of knowing how long CDs or DVDs have been sitting around before you purchased them, limit your "bulk buys" to the number of disks you can reasonably expect to use in one year.  Just to be safe.

5. Use CD-R media for longer term storage.

CD-R (write-once CD's) exhibit the longest life expectancy among the CD and DVD options on the market.  Rewritable CDs and DVDs use a less stable metal alloy than used in write once discs.  Stick with CD-Rs first and DVD-Rs second when your goal is long term storage.

6. Handle CDs and DVDs with extreme care BEFORE they are burned.
Any dust, scratches or fingerprints that are on a CD or DVD when it is being recorded can cause lost bits of data. Any of these imperfections can cause the laser beam to scatter during the recording process.  The result could be lost bits of data and "disk errors" when you attempt to retrieve the information.  Handle the media with the same care you would use with a priceless photographic negative.

Ultraviolet light will degrade the dyes used on the recorded surface of CDs and DVDs.  Humidity gives rise to corrosion which accelerates the deterioration of disk and data integrity.  This is also true of CDs that use silver as their reflective metal surface.  Only Gold CDs seem resistant to high humidity. 

Under no circumstances should these disks be exposed to direct sunlight.  Sunlight attacks the properties of the dye layer, and the associated warmth of sunlight speeds ups degradation.

8. CD and DVDs are best stored in plastic cases to prevent warping and minimize exposure to atmospheric contaminates.

Plastic CD and DVD cases afford the maximum protection. These cases shield the optical media from the harmful effects of light, humidity and environmental contaminants.

9. Store recorded CDs or DVDs in a vertical position.

Storing CDs in a horizontal position allows the disk to warp over time.  Storing the CD in a plastic case in a vertical position allows the "hub" in the center of the case to provide the support and reduce the potential for warping.

10. Avoid scratches on either side of the media, but scratches or abrasion on the LABEL side are of the greatest concern.  Because the reflective metal layer and data recording layer are very close to the surface of the label side of the disc any scratch or abrasion to this side of the CD can result in loss of recorded digital data.

11. No smudges, fingerprints, dirt or dust. 

An excess of these imperfections affects the laser’s ability to focus.  Fingerprints, dirt and dust can reduce the light intensity of the laser passing through the disc by scattering the beam.  More "disk errors" are caused by smudges, fingerprints, dirt and dust than by scratches.

These last two tips are no different than the care we would give to negative, slides or that carefully stored collection of 33 1/3 record albums.

12. Using adhesive labels or a pen on the surface of a CD or DVD can be life threatening.

Just as labels and pens are important considerations when signing fine art photographs, the same is true of CDs and DVDs.  Water-based, soft-tipped markers are less likely to penetrate to the reflective coating or recording surface.  Soft-tipped markers will avoid the possibility of scratching the sensitive label-side surface.

After reviewing all the recommendations about using adhesive labels on CDs and DVDs, I've come to the personal conclusion that it is best to avoid using any adhesive labels altogether.  Labels can cause balance problems (acting like the weights used to balance automobile tires) while the disk is spinning and being read.  Labels also tend to "bleed' some of the adhesive chemicals over time (about 5 years), and can actually work its way into the reader's drive mechanism -- "gumming" up the works.

A category of CDs and DVDs are on the market that have been coated (on the label side) with a layer that accepts printer ink.  Producing a CD or DVD label using an inkjet printer appears to be safe.  However, the mere act of placing a CD or DVD in a printer opens the possibility of introducing scratches, fingerprints, dust or smudging to one or both sides of the media.  That's not a good thing.

These considerations are minor when looking at the bigger "file storage" picture.

The most significant threat to the life of the digital image files you store on CDs or DVDs today is tomorrow’s technology.  So, even if you are diligent in the recording, care and storage of the CDs or DVDs you create today, there’s no assurance the mechanical reading devices will be available in 50 years to access those files.

That next evolutionary step is closer than you might think.  As Blu-ray Disc and HD DVD formats proliferate the video market, they will certainly become factors in the storage of computer image files.  When that day arrives, every photographer will need to transfer their files to these new formats BEFORE those safely stored CDs become obsolete, data formats change or new media reading devices are no longer backward compatible.  How are those old “Zip Drives”, “Benoulli Boxes” or 8-inch floppy disks doing?  Remember BetaMax and 8-track tapes? Same story.

You have undoubtedly experienced this problem in the past with even the simplest word processing program.  When you moved from one version of a program to the next or tried to import a document into another word processing program, did you lose some or all document formatting?  The same could happen to image data files when migrating from one format to another.  And, if you decide to skip a generation or two of the evolutionary development, you may find that the new recording/reading devices are not backward compatible -- making your old files inaccessible.

All this may be a depressing way to start your day, but it is a stark reminder that we cannot be content just “burning” our files to a CD or DVD.  Neither the media nor the media recorder/player will survive the rapid evolution of digital technologies.  Photographers (amateur and professional) must develop strategies for moving their valuable files to the next generation of storage technology.  It’s a concern for professionals who want their work and the income it generates to pass to future generations.  For amateur photographers, it’s a matter of preserving the visual history of their families.

Another option is to let someone else worry about the problem.  I have elected this strategy as my primary method of ensuring the future accessibility of my data files.  For $60 a year, I have purchased an archival insurance policy.  I use the Mozy online backup service for the long term storage of my image files. On one of the external drives that Mozy continually monitors and backs up is a folder I have labeled as "ARCHIVE".  I place all my final image files in this folder.  I continue to do my own local daily hard drive back ups and copy critical files to CD-Rs. 

But having my most valuable files stored by Mozy ensures that regardless of technology changes, I will always be able to access my files despite technology changes.  Mozy has assumed the responsibility of keeping on top of storage technology and making my files retrievable.  (Note: A some point it may be necessary to convert my old data to a new format.  This is true of any stored data.  But this online storage option affords me the security of knowing that my original files will always be available to perform this conversion.)

Their is a "peace of mind" factor associated with this strategy as well.  I now have a copy of my most valuable files stored at a second location.  If a natural disaster or some other devastating event happens in my home office/studio, I will always be able to recover my files from Mozy. There are several online back up services, like Mozy, that are worth researching.

(There is a minor risk that Mozy might quit the business.  But, the normal business practice in these cases it to allow customers to download their files before the company closes its doors.)

Even if manufacturers are 100% correct in their estimates, and the physical CDs/DVDs and data we record today survives to the year 2310, it is an evolutionary certainty that the reading devices will someday be replaced with the next "big thing".  Given the history of computer storage advancements, an optimistic estimate would place the USABLE life expectancy of CDs and DVDS in the 20 to 30 year range.

In practical terms, the potential life of CD and DVD-stored digital image files is best expressed in terms of their technically viable life expectancy (the time during which the mechanical recording and reading devices are available) -- approximately 20 to 30 years.  It’s time to start planning.

Note:  David Saffir, a frequent Guest Commentator on PMPN, a fine art photographer and a judge for PMPN's monthly photo contest, has just written an article concerning hard drive back up practices.  His article is a worthwhile companion story to this PMPN CD/DVD report.