Exercise 19: Correction

The first exercise of the part IV looks at the issues like dust shadows and lens /polygon flare. Tolerance for these two issues is very personal, and at times also industry specific. There is a difference between both the abnormalities; one is out and out an external particle on the sensor or on the lens (obviously it is very easy to rectify the later). Where as, lens flare is the result of light reflecting inside the lens, either from lens faces or from internal mechanisms of the lens. Normally very undesirable effect, unless used creatively. A very good read on les flare http://www.cambridgeincolour.com/tutorials/lens-flare.htm (accessed on: 2nd March 2012)

I have only one camera body and 4 lenses. I tend to change lenses depending on the scene requirement. Most of the times, trying to be really cautious and quick in changing the lens. Till now I have been extremely lucky and haven’t faced the dust on the sensor. Or may be, it is the sensor cleaning mechanism of Nikon 300s, which has been protecting me perfectly from the issue. http://imaging.nikon.com/lineup/microsite/d300s/en/specifications/ (accessed on: 2nd March 2012). However, there are many people, who have actually faced nasty dust particles on the sensor. They might not agree with Nikon’s auto sensor cleaning claims. I am not too daring, when it comes to repairing small camera issue. I would always look for an authorized service center for any sort of repairs. However, there might be times, when knowing how to clean the sensor might be handy. Read this blog by Thom for a detailed explanation on the topic http://www.bythom.com/cleaning.htm (accessed on: 2nd March 2012).

I have selected two images from my archives that have the above two issues. Let me go through them one by one.

Dust shadow / blemishes:

The image of the “Jumeirah beach hotel” was shot at 1/30 sec @ f/18, ISO 100. I remember precisely that I had cleaned the lens with a dry cloth. However, there were some marks still left on the lens, somehow I had missed them. When I transferred the images to the computer, for sure it was visible and quite annoying.

Ex 19-JBR-with spots

See the image below at 100% magnification; clearly one can see that these spots are distracting enough and needs to be removed.


This image is a straightforward case; it does not have any surface next to the spot with complex details. Hence removing the spots was a very easy task. In Lightroom 3, spot removal option with “Heal” highlighted worked very beautifully. For more complicated jobs, cloning tool might work better. It is very important to pay special attention to the colour tones of the parts being rectified as at times we may end up having slight variation. This can result in patchy final product.

Certainly Photoshop does much better job in this area. It gives more flexibility and variations of methods.

Ex 19-JBR-final

Lens / Polygon Flare:

For this, I have chosen an image for my archives. This image was shot from a helicopter in New Zealand. Hence, there are many reflections in the image. That is the reason I have never used this image on my website. I was trying to make creative use of the smaller aperture to get the sun with the streaks (for once risking the lens). I noticed the strong reflection of the windscreen and decided against the idea. The image was shot with 1/100 sec @ f/22, ISO: 100, Focal Length: 21mm.

Ex 19-with lens flare

In the above image, the places highlighted with the red circles are affected with lens flare. It surely is not an artistic look and needs to be rectified in case I am interested in using this image. To remove the lens flare I have used the combination of “Heal” and “Clone” tool in Lightroom 3. See the image below for the rectified version.

Ex 19-no lens flare

In the rectified version one can see that the healing tool has taken care of the lens flare. However, in the bigger area the results were not satisfactory. It was given bit of patchy feel to it. Now to correct the image even more I have imported the image in Photoshop and used the tools like patch tool, and clone tool.


Surely the bigger area affected with lens flare has been rectified more precisely with Photoshop tools. I can go on in correcting all the reflections and other defects. However, I feel restricting myself to bare minimal correction.

Conclusion: To me dust removal is a basic manipulation. As long as I am using the image for the non-documentary purpose, I would not hesitate to rectify the dust spot to salvage a beautiful image. When it comes to lens flare, it really depends on the degree of defect. If it has any artistic feel to it, I would probably leave it as it is. If it were a small distraction, I would remove it depending the purpose of the image. However, if images were for photojournalism, I would go by the guidelines of the publication.

I have not put in any research, in the area of handling the lens flare in the film days. May be cropping or dodging the area, were the choices available. If it was accepted in those times, then having some tolerance to such corrections in the area of digital photography would be justifiable.


8 thoughts on “Exercise 19: Correction

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