Sep 252011
  • “Would I be able to get a blurred background with this Camera Model?”
  • “Is this a good lens? Will it give me an Out Of Focus background?”
  • “How can I get those blurred out of focus areas you guys refer to as Bokeh?”
  • “How can I isolate my portrait subject by rendering the background out of focus?”

These questions, and similar phrases implying the same or similar meaning, are those which I have come across most often when youngsters, interested in pursuing photography or planning to buy camera equipment, start asking about different aspects of photography and the equipment they either have or wish to buy or expand upon.  I have also come across individuals who have invested an extensive sum of money in buying top of the line gear, asking similar questions while seeking to know what their equipment and set-up is capable of doing. Intrinsically, I am always willing to share, hence I welcome these questions, and always try my best to satisfy the curiosity of the person seeking an answer.  However my take and approach on this subject is a bit different.  In a moment you will find out why it is so.

Indeed, one of the most debated, discussed and dissected subjects on most photography forums, spaces and streams is the subject of “Blur”, also affectionately referred to as “Bokeh”, “Background Blur”, “Subject Isolation”, “Creative Blur” and so on and so forth.

In a lot of cases, whenever such a discussion starts on a forum or social network,  more often then not, one would find it consistently revolving around the “Aperture” of a lens, and a good level of Bokeh or Blur would, in most cases, be attributed, knowingly or unknowingly, to “how wide an aperture” or “how bright a lens” you can use.  Indeed, there is absolutely nothing wrong with this notion… in fact, a bright, wide or comparatively wider open lens aperture does play a key role in providing pleasant, out of focus areas within your composition. But then, in reality,  does having a wide aperture alone provide you with a Pleasant, Creamy, Buttery, Subject Isolating Blur?  The answer to this question is where the domain of the “Aperture” ends and everything else pertaining to creating a “Pleasant, Creamy, Buttery, Subject Isolating blur, begins. The “Aperture” is the tip of the iceberg. An entire mass lives deep beneath.

Coming back to the questions I began this writing with, on most of the instances when I have answered any of these or similar sounding questions, my answer has been short yet deep…  My deliberate choice of response is…  “It Depends!”.   And trust me… It really DEPENDS!!

Before I move deeper into this subject and present to you some concrete examples to explain some of the nitty-gritties behind it, it is essential to understand what the term “BLUR” or “BOKEH” implies in reality.  To some, a mere out of focus area in front of or behind the subject would suffice to give them “their Desired Blur”.  To many others, unless the out of focus areas are creamy and smooth, their pursuit for “The Perfect Bokeh” continues.  But then, what exactly is this BLUR.  What causes it, and why it happens?

Lets take a look at the four images below and take a moment to talk about the impact of aperture in creating a blurry out of focus background. Without much of an effort, most of you would easily be able to see that the background blur in each of these photos is significantly different when compared with each other….

The Blur Factor~20110709-DSC00088~50 mm~1-640 sec at f - 1.4~ISO 100 The Blur Factor~20110709-DSC00096~50 mm~1-640 sec at f - 1.4~ISO 100 The Blur Factor~20110709-DSC00092~50 mm~1-640 sec at f - 1.4~ISO 100

The Blur Factor~20110709-DSC00097~50 mm~1-640 sec at f - 1.4~ISO 100

So, did you see the difference in the quality and texture of blur in each of the above photos? 

I am sure, most of you did. However, I do wonder how many of you keenly observed that the entire camera settings have been clearly mentioned on the lower border of each of these images… and…  SURPRISE! SURPRISE!  If you may have observed keenly enough and compared, you would notice that the camera settings given on each photo is EXACTLY IDENTICAL!! Winking smile.

No, this is certainly not a typographical error Winking smile.  It is a fact that each of the above four images were taken on a brightly lit day in natural light, with a 50 millimeter prime lens, with it’s aperture set to f/1.4 and shutter speed set to 1/640th of a second, and light sensitivity set to ISO 100.   The camera settings were 100 percent identical.  Further more, the angle of view and image framing and size of subject in the frame were all identical as well.  Interesting… isn’t it? Winking smile

Let us review one of the aspects of the camera setting first… the Aperture.   All of the above four images were captured at an aperture of f/1.4, which is perhaps one of the largest common aperture found amongst bright prime lenses, with the exception of  f/1.2, f/1.0 and f/0.95 lenses, the later two of which are neither commonly manufactured nor commonly used.  Given this fact and evaluating from a generally accepted rule of thumb or a common understanding amongst new entrants and amateur photo enthusiasts, having used one of the widest and brightest of apertures in capturing the above four images, the quality and texture of the background blur on each of these images, technically, should have been almost similar, if not identical.

Why is there a difference then?, you may ask.   The answer is… A wide and bright aperture, though desired, is not capable of creating a creamy subject isolating blur in isolation and entirely on its own.  It is only when such a wide aperture is used in conjunction with other key aspects of equipment and compositional understanding and methodologies that one is able to achieve a more pleasing bokeh and a blur which effectively isolates your desired subject.

Before we move further, let us quickly review and evaluate the reasons why there is a difference in the quality and texture of blur between each of the above images.

  • As discussed above, the camera settings, including ISO, focal length of the lens and shutter speed are the same for each of the above images.
  • The framing on each of these images, which for a prime lens**(see side note below), is determined by the distance between the camera and the subject, is the same on all of the above four images.
  • On the first image, the distance between the subject and the background, is more. This has effectively helped in causing a higher level of blur to the background.
  • On the second image, the the subject was moved closer to the background, causing the distance between the subject and the background to be reduced.  This reduction in distance has reduced the overall blurring of the background, by bringing the background more into focus compared to the first image.
  • The third and fourth images have the same aspects as described above, i.e., the subject placement being made away from the background in the third photo and closer to the background in the fourth.  However, with these aspects being identical, the background blur in the first photo and the third photo should have been identical as well, since both of these also have the same subject to background distance.   The thing which creates a difference between the first and the third image, in spite of everything else being the same, is the “Point Of Focus”.  On the first image, the focus is on the face of the subject, where as on the third image, the subject has extended his hands forward and the focus is on his fingertips, which brings the point of focus at least 24 to 30 inches closer to the camera, Due to the lens focusing on a closer point in the third image, it helps rendering the image background more out of focus compared the the first image.

We will shortly revisit and discuss what is the relationship of blurring backgrounds with that of distances between camera to subject and between subject to its background.  For the time being, let us move on and discuss a few other aspects which impact the blur factor.

(**A side note for those who wish to understand and differentiate between a prime lens and a zoom lens. A prime lens has a fixed focal length, like the 50mm or 85mm or similar other prime lenses.  In order to change the composition and framing with a prime, you have to move closer or away from the subject to bring more or less visible area into the captured frame. With a zoom lens, like the 18-55mm lens or 75-300mm lens or similar other lenses, and many variable zoom point and shoot cameras, you can change the framing and visible area of the subject by zooming in and out while remaining stationary at your location, without changing the physical distance between camera and subject.)

Just to jog back a few strides… remember what I mentioned regarding the Aperture part of the blur equation… “A wide and bright aperture, though desired, is not capable of creating a creamy subject isolating blur in isolation and entirely on its own”. Then we moved on and we discussed two of the reasons which aid in producing a higher or lower quality and texture of blur. These were the ”distance between the camera and the subject” and the distance between the subject and the background”. Now let us add one extremely key ingredient to the blur factor.  “The Focal Length Of A Lens”.  And since pictures are worth a thousand words, let us review a few images before we evaluate and discuss how the focal length adds to the equation of the Blur Factor. 

The next four images were all taken with a 70-210mm f/4 zoom lens.  For each of the image, I changed one or more aspects of the composition, including focal length, aperture and shutter speed.  ISO settings were maintained at ISO 100.   Don’t forget to see the camera setting details mentioned on the lower border of each image. It will help in understanding what we will discuss next.

The Blur Factor~20110709-DSC00107~105 mm~1-125 sec at f - 4.0~ISO 100

When evaluating the above image, do realize from the framing and composition that the subject has been placed closer to the background and technically should give a lesser quality of blur, which doesn’t happen to be the case. The focal length used for this image was 105mm which is a little over twice the focal length compared to that of the earlier four images which were taken at 50mm.  In order to keep an almost similar framing and composition, while using a focal length of 105mm, I had to move my camera away from the subject by about twice the distance as much as it was when I used the 50mm lens.  By moving away from the subject, I was able to compose almost a similar (slightly more zoomed in) frame as was done with the 50mm.   However if you look closely, I used an aperture of f/4.0, which is three full stops narrower compared to the completely wide open aperture of f/1.4 used in the earlier images.  Yet, surprisingly, the blur in the background and the quality of its texture has increased and have become comparatively better in the above image than the first image taken with the 50mm at f/1.4.   Let us see the remaining three images from this group.

The Blur Factor~20110709-DSC00114~210 mm~1-125 sec at f - 4.0~ISO 100

The Blur Factor~20110709-DSC00115~210 mm~1-30 sec at f - 8.0~ISO 100

The Blur Factor~20110709-DSC00117~210 mm~1-8 sec at f - 16~ISO 100

As you would have seen by now, the above three images were taken at a focal length of 210mm.  The position of the subject and his distance from the background was the same as was in the image taken at 105mm.  I also had the camera set up at the same position as with the 105mm image, as such, while zooming the lens to 210mm focal length,  the area within the frame changed from a torso image to a head shot.  The key thing to understand here is this….   On the first of the above three images, the aperture was set to f/4.0, same as the 105mm shot which was 3 full stops slower/narrower compared to the fully open f/1.4 used with the 50mm.  Yet, the quality and texture of the background blur tremendously improved, making it more creamer and softer compared to any of the other exposure equations I have presented so far.

The second image from the above 210mm group was taken using f/8.0, a full 5 stops narrower and slower compared to the fully open f/1.4 used with the 50mm.  In spite of this, the quality and texture of the blur taken with 210mm at f/8.0 exceeds that taken with the 50mm f/1.4.

The third image at the 210mm focal length was taken with the aperture set to f/16, which is a whooping 7 stops slower and narrower compared to the f/1.4, and only at this point the background blur is somewhat comparable to the images taken with the 50mm f/1.4.

For all of the above four images taken with the 70-210mm zoom lens, keep in mind that the subject to background distance was fairly less, where as the distance between the camera and the subject and the focal length were increased.

Lets add two more images to the equation…

The Blur Factor~20110625-DSC00036~500 mm~1-40 sec at f - 6.3~ISO 100

The Blur Factor~20110625-DSC00037~500 mm~1-25 sec at f - 8.0~ISO 100

Both of the above images were taken at 500mm focal length.  The background in this case was just about 4 feet behind the subject and was somewhat a busy background.   Yet, with the usage of 500mm focal length, used at apertures of f/6.3 as well as f/8.0, the background is reasonably blurred.

While on the subject of using focal length as a factor to create blurry backgrounds, I would like to share 3 more images which would help adding another dimension to the blur factor.  So far, on all of the images shared above, the subject has been placed fairly close to the background, within 4 to 6 feet distance.  Lets see what happens when, while using a longer focal length, we also bring in a longer distance between the subject and its background.

The Blur Factor~20090311-DSC09930~400mm~1-25 sec at f- 8.0~ISO 100

The Blur Factor~20090311-DSC09941~400mm~1-30 sec at f - 8.0~ISO 100

Both of the above images were taken with a 200mm f/4.0 prime lens, at an aperture of f/4.0 but with a 2X teleconverter added to the lens. This effectively changed the focal length of the lens to a 400mm. However the 2 times focal length multiplier also caused the effective aperture of f/4.0 to be reduced by 2 stops to make it an f/8.0 lens.   The key aspect in this image worth identifying here is the distance between the subject and the background, which was at least 25 to 30 feet away.  This resulted in a beautifully creamy background blur, enabling to perfectly isolate and bring full attention to the subject.

The Blur Factor~20090314-DSC00154~200mm~1-640 sec at f - 4.0~ISO 100

The same 200mm f/4.0 lens was used in the above image, this time, without the 2X teleconverter.  In this image, the background was about 20 feet behind the subject, however I utilized the minimum focusing distance capable on the 200mm lens to take this shot, which allowed me to get my camera closer to the subject, resulting in a beautifully and completely blurred background.

Up until this point, we have indeed covered a lot of ground.  We talked about the Aperture, the Point Of Focus, the Distances, the Focal Length of a Lens and we carefully added each mix to the Blur Factor equation, reviewing the end result achieved through each change and / or addition.  What all of this leads us to, is something extremely important in order to understand photographic composition and the correct usage of your camera, lens and its settings.  All of these factors, in their own isolated usage, as well as when combined, cause what in photographic terms is referred to as “Depth Of Field”, or as affectionately referred to by seasoned photographers and novices alike, the “DOF”.

What has DOF got to do with the Blur Factor, you may ask.   Well, almost Everything!!  Winking smile.  Every single element so far discussed, directly or indirectly causes a change in the Depth of Field whereby causing a change in the blurring of a section of your image, may it be the foreground or pertaining to the background. We are able to find tremendous quantum of information on the web which explains in detail as to what Depth of Field is, why is it so and how it works.   I would try to only touch upon the subject of depth of field, purely from the standpoint of explaining the relation between DOF and the Blur Factor.

When a camera and lens combination is focused on a “Point Of Focus” to capture an image, the maximum distance that remains in sharp focus in front of and behind that “Point Of Focus” is called the Depth Of Field. If for the sake of this explanation we call this sharply focused area as the DOF Zone,  then effectively anything that appears prior to the front most point of this Zone and after it’s rearmost point would start showing a sign of being out of focus, hence causing a blur.  The actual DOF Zone, however, changes as a direct result of Aperture, Focal Length, and Distances.

  • A lens equipped with a wide open aperture, similar to a 50mm lens with an f/1.4 or f/2.8 aperture opening is capable of having a short DOF Zone, in other words, a shallow depth of field.  I deliberately used the term “capable of having”… the reason behind it is that this and similar other lenses, in spite of being used wide open, if focused to just before or around a median point within your frame (technically termed as the Hyperfocal Distance), would render most of the image in front of and behind the focus point in complete focus.  However, when creatively used to capture a subject and managing the distances with a need to have background blurred and your subject isolated, it can cause to have a shallow depth of field, whereby generating a blurred background.
  • A lens with a focal length falling within the genre of a Telephoto Lens, which typically starts 70mm onwards, would be capable of demonstrating a very shallow depth of field.  A telephoto lens falling within 400mm to 600mm and above would have an extremely shallow depth of field even when focused on far out objects.  Such a telephoto lens, when equipped with a wider aperture like f/2.8, f/4.0 or f/5.6, can easily create a beautifully blurred background, with a crisp and clean subject totally isolated from its surroundings.
  • As for the distance,  the closer a subject is to the camera, the shallower the depth of field becomes, Similarly, the further the subject is from its background, the shallower the depth of field becomes.  However the integration of distance into the The Blur Factor equation, cannot play a role in isolation and is dependent entirely on the Focal length of the lens and its aperture used for a specific capture. You can see this integrated into some of the above example images.
  • Last, but not the least, when we talk about the Focal Length of a lens, in principal we are also talking about the Angle of View of that lens.  Consequently, a lens with a Narrow angle of view, like a Telephoto lens would be more capable of creating a pleasant blur due to an intrinsic shallower depth of field compared to a lens with a wider angle of view, like a 24mm or 18mm lens, which can hardly create any out of focus blurred backgrounds or foregrounds.

Lets take a 360 degree turn and share with you two images where you should not expect to see any back or foreground blur at all.  Winking smile

The Blur Factor~20110709-DSC00140~22 mm~1-160 sec at f - 4.0~ISO 100

The Blur Factor~20110709-DSC00143~24 mm~1-6 sec at f - 16~ISO 100

A wide-angle lens and background blur do not go anywhere close together Winking smile.  Even if you have a wide angle lens with a bright aperture of f/2.0 or f/2.8, except when the Point of Focus of the lens is reasonably close within just a foot or so, it will render everything in focus in almost all other instances.   As you can see from the two images above, where the first one was taken at 22mm f/4.0, whereas the second one was taken at 24mm f/16.  No doubt that the one taken with f/16, has every single element in sharp focus, yet the one taken even at f/4.0 is a totally different image compared to many of the f/4.0 or narrower aperture images taken with lenses of 50mm focal length and longer.

So, how do we carry all of the above in a small drive-thru takeaway package? Something which everyone can enjoy on the go…   Well… as said, “the devil is in the details”…. however, I would surely try to squeeze all of this into something which may come in handy on the go…  so here you are:

  • The wider the Aperture, the shallower the Depth of Field (DOF), equals better background blur
  • The longer the Focal Length, the shallower the DOF, equals better background blur
  • The narrower the Angle Of View the shallower the DOF, equals better background blur
  • The closer the Distance between Camera and Subject, the shallower the DOF, better background blur
  • The longer the Distance between Subject and Background, the shallower the DOF, better background blur
  • Combine any two of the above factors together, your Blur Factor multiplies. Example: A 200mm lens with an aperture of f/2.8.
  • Combine any four of the above factors, and your Blur Factor Quadruplies (wonder if there at all is such a word) Winking smile.  Example would be a 200mm lens with an aperture of f/2.8, with the subject placed 12 feet from the camera and 30 feet before the background Winking smile

OK, now I am not supposed to tell you everything… so go out there, do some shooting and put what you may have learned from this post to use, and consequently, learn more in the process.  As I had said in another post on this blog, digital photography has really become affordable. If you own a digital camera, you have already incurred all the expenditure there was to it. Your first shot cost you the amount you paid for the media card…. all your subsequent shots are free.. at least for the life of that media card!!…   The luxury of the Digital Era!

You thought this was the end… didn’t you???  Well not really…..

The Blur Factor….. and Beyond..!

There are two other areas pertaining to The Blur Factor.

One of these is so blurry that photographers try to come up with various techniques to actually overcome and reduce the blur.   This is the extremely addictive world of Close-up, Macro and Extreme Macro photography, where photographers try to get as close as possible within the close-up domain, while some try to achieve a 1:1 life size macro image capture on the camera sensor, yet other even try to exceed their own and their equipment limits by capturing bigger than life size extreme macro image 2:1 and beyond.  The depth of field at such close and hyperclose distances is so extremely shallow that while trying to get the head of a tiny insect into sharp focus, you come to realize that the rear part of the insect’s body has gone blurred and the surrounding turned into an ultra creamy and smooth blur.  On such occasions, using a narrowed down aperture to a lens’ lowest aperture limit is also sometimes found to be a barrier, with a need to narrow down further or to delve into the domains of focus stacking.  I would leave this subject here, to be covered in another blog post as this subject is as detailed and unique as the Blur Factor itself.  Hopefully, I would be able to come up with the post soon.  Just to give you a sneak peek into the subject, let me share that on a few occasions, I have had the opportunity of narrowing down my aperture to and beyond f/32, and yet, the Blur Factor prevailed…Extreme Macro - N0000087

Extreme Macro -20101105-P1060292

Another area pertaining to the Blur Factor is “Creative Blur” or “Creative Bokeh”.   A vast array of techniques are being used by professionals as well as novices to come up with a blur on their images, either on the subject, or it’s foreground, or background, all of which appear pleasing to the viewer.  This is another area which needs to be explored in an independent way, and I would soon be writing a more detailed post about this subject.  Meanwhile, have a look at few of the creatively blurred compositions…

The Blur Factor~20110422-DSC08083~50mmLB~1-60 sec at f - 2.8~ISO 200

The Blur Factor~20110602-DSC09459~50mmLB~1-60 sec at f - 2.8~ISO 100


That is all for now, folks.  I hope you enjoyed the post and found this topic and what has been shared in this post to be of some usefulness towards your goal of creating better images.  Wish you best of luck with your snapping session.  I would eagerly be looking forward to your thoughts and comments.

Until the next post, have fun and all the best!


  7 Responses to “The Blur Factor!”

  1. what a detail article on simple subject ! thank you so much for the in sight on so many aspects, oh i so wish i had idyllic memory and i could remember these points ! and if bokeh factory has so much in it i wonder the other topics you’ll touch would be like dissertations ! *winking smile*

  2. what a detailed article on simple subject ! thank you so much for the insight on so many aspects, oh i so wish i had idyllic memory and i could remember these points ! and if bokeh factor has so much in it i wonder the other topics you’ll touch would be like dissertations ! *winking smile*

    • Thank you, Hina. I am always amused by your comments, as you have a tendency to brush up the lighter side of things so very well. Much obliged. I do hope I don’t end up making these blog posts like a dissertation… No one is going to read it then.. LOL. ; ))

  3. one word Omer bhai “WOW” I dint know how such little things can effect the overall science of an image. bookmarked this already for the time my dslr arrives and I will try these for sure inshaa Allah 🙂

    • Thank you Ghayyur 😉 Hope you would find it useful once you transition to your DSLR. It would be worthwhile noting that the same principals and lessons learned from here can also be applied to many point and shoot cameras with appropriate placement and composition of subject, given the zooming capabilities and significantly good aperture of some of the modern day point and shoots of various camera brands.

  4. Brilliantly explained Omer Bhai. We seek further technical aspects on MACRO Photography.

    • Much obliged, Fasih. I hope the knowledge shared in these pages would come in handy.

      As for Macro, thank you for sharing your interest. I will inshaAllah soon be writing about Macro and its related aspects.


 Leave a Reply

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>