Savannah Photographer Dale Reagan

Is it a bird? a plane? a blob?  a digital dust spot?

Ever noticed strange looking dark blobs (spots that are usually small) in only some of your photos?  They don’t show up in every image – only when the camera is optimized to reveal them (for me this is usually when using a higher aperture and close to a hyper-focal distance focus setting.)  The image below shows some ‘real’ spots on a image from a camera that needs a sensor cleaning – if you notice similar spots in many or most of your images then a dirty sensor may be the problem.

'Spots' on a digital camera sensor.

Older digital SLR cameras are more susceptible to this problem – according to manufacturer’s descriptions of their newer model cameras with self-cleaning sensors.

Eventually, you will need this information: the process of changing lenses on DSLRs provides ample opportunities for dust to contaminate your ‘low-pass filter’ and/or image sensor.  After months of shooting I  noticed a ‘consistent dark spot’ on my images – sure enough a quick check revealed a ‘blob’ on the low-pass filter – cleaning was required.   A few weeks later I noticed that I seemed to be experiencing  some lens ‘vignetting’ – another review for ‘dust spots’ revealed a concentration of dust-like pixels in the corners of my images – another cleaning was in order.

Your camera manual should provide some information on ’sensor’ or ‘filter’ cleaning – the link below is for the brave folks who like to handle this themselves – otherwise you should see your camera dealer or seek an authorized repair facility for your camera.  While it is possible to ‘clean images’ in editing software I think everyone happier if the images don’t need such tweaking.  If you only have small ‘dust spots’ then your photo editing software may have simple tools to assist you in removing such spots, i.e.  the  ‘healing brush’ in Adobe Lightroom or Adobe Photoshop.

How do you prevent such digital image spots?

1. Only change your lenses in a ‘clean’ environment (in-doors, away from dust, sand, dirt, wind, etc.)
2. Clean your camera lens mounts prior to changing them.
3. Clean your camera lenses.
4. Have your digital camera professionally cleaned by an authorized service center.
5. Do your own cleaning with one of the kits available for this purpose (visit the link below or search for ‘digital sensor cleaner’ or similar terms.)

How  do you fix or clean dust spots in an image?

1. Use digital photo editing software to remove or replace the spots, i.e. use the healing brush tool found in Adobe Products like Adobe Photoshop CS4, Adobe Photoshop Lightroom 2, Bibble Labs or other tools.  In many cases it as simple as red-eye-removal:  a) select the tool, b) set your brush/tool size to be slightly larger than the spot and c) click on the spot to remove it.
2. Use your camera options that provide a somewhat automated image cleaning process, i.e. some Nikon camera models and software provide a multi-step process where you create a ’spot mask’ image which you use as a filter with the Nikon software and the end result is that the spots are removed.

Cleaning Digital Camera Sensors – this is a link to an external site devoted to this topic.  The site appears to offer a comprehensive review of solutions and approaches for cleaning your digital camera sensor.  I recently located what seems to be a reasonable video demonstrating how to clean a digital camera sensor (using a ‘wet’ approach.)  Also, your camera probably has a ‘mode’ (i.e. ‘mirror up’ on Nikon D200) which allows you to review the low-pass sensor for dust – if the particles are large then they can easily be seen (and will consistently show up in your photos…)

Which Statement is True?

A Camera Never Lies… or

A Print is only one possible interpretation of an image…

Both have merit and both have depend upon human and medium variables.  In the old (film) days there (very broadly speaking) were two types of photographers:

1. those who created photos and hired out developing and printing and
2. those that handled print creation from start to finish.

The basic limits of what could be done with a print were tied to the  quality of the original negative image;  the printing process allowed for an additional creative touch to be applied to the final print.  Those photographers who handled all of these steps could of course have maximum creative input into the final output.   It should be noted that most (if not all) aspects of image creation and printing were controlled by the photographer or printer.  The choice of film brand, type, ISO as well as the choice of chemicals and papers used all affect the final outcome and, in  many cases become a type of signature for a photographer or printer.

In the digital photo world these factors are still in play (or they can be.)  Camera manufactures have made tremendous, perhaps even miraculous progress in developing current digital cameras (entry level to pro dSLR systems.)  Photo-printer manufactures have made similar levels of improvements.  It is now possible to click the shutter button, wait a few seconds for the image to pass through the air to your wireless network, reach your computer and then be shuttled to your inkjet printer – all  without you having/needing to decide on any camera settings, computer settings, printer settings, nada!   Provided that your ink levels are good and your photo-printer paper is of reasonable quality you will most likely wind up with a print that is acceptable and it may even be a photo that your share with others.

If you take the ‘no-hands’ approach described above then for each auto setting you use you are actually allowing the camera (i.e. the knowledge/wisdom/skill of the camera, printer, computer & software engineers) to pick for you.  There is nothing wrong with this – it’s just a choice that you make; most serious photographers (pro and non-pro) will make these choices (i.e. they won’t use any automatic settings.)  Does this really make any difference?  So far, no, not much difference – well, not until you start doing truly creative things with the image/print.

Cameras (film or digital) are really, really, really dumb – compared to the combination of the human eye and brain.  The camera will never ’see’ the level of image complexity that we perceive in a scene (our eye/brain combination is a 3d view; a camera only has a 1d, flat view.)   So, a camera never lies really means that a camera never sees the whole truth…  How about:  the print never lies? The camera is much closer to the original image – any print that we encounter is in fact, one interpretation of any given image and as such, is much less likely to be close to any sort of truth – a digital negative (file) is much closer to the truth (errr, the camera’s truth.)

JPEG, TIFF, RAW – the Digital Negative

Camera manufactures offer you choices – most cameras include an option for RAW files.  The choice of digital negative file type impacts image quality and places practical limits on what can be done with your negative.  JPEG  files are cooked – i.e. they are sort of like using other automatic settings – they limit your creative input control.  RAW files allow the most flexibility for post-processing.  A simple example is the choice of light temperature (i.e. setting the camera for daylight, night, cloudy, etc.)

If you have a RAW file then you can change this after the photo has been taken; if you use a JPEG file then you have to re-process the file (i.e. create a new file to use) to fix a problem like this.  Since a RAW file is never a work-file, you could argue that there is no difference.  In addition, the latest version of Adobe Lightroom treats all negative files as if they were RAW files (any changes result in the creation of a new file so the original is never changed.)  If your camera supports it I suggest that you try using a setting that provides you with both a RAW file and and a JPEG file – only then will you be able to see the differences in both types of capture.

NOTE – since I first wrote this many software products have changed – many current products allow you to treat a JPEG file like a RAW file, i.e. any changes are made to a copy of the original file so your ‘negative image‘ is preserved as long as you use software that does not change it…

Photo editing/printing is about choices – what do you like/prefer?  More saturated images? more realistic images?

The LAB color space provides some quick and easy methods for altering/boosting color – especially for certain types of images.   Please note that these images are not final images – they are simply examples of what can be done.  The effects made by changes in LAB color may not be appropriate for every image (even those shown in these examples);  you need to target the final output medium when you are working on any image.  Click here to view larger examples of LAB color adjustments (Flash gallery.)