About Me

My photo
Spofford, New Hampshire, United States
Jeff Newcomer has been a physician practicing in New Hampshire and Vermont for over 30 years. Over that time, as a member of the Conservation Commission in his home of Chesterfield New Hampshire, he has used his photography to promote the protection and appreciation of the town's wild lands. In recent years he has been transitioning his focus from medicine to photography, writing and teaching. Jeff enjoys photographing throughout New England, but has concentrated on the Monadnock Region and southern Vermont and has had a long term artistic relationship with Mount Monadnock. He is a featured artist in a number of local galleries and his work is often seen in regional print, web publications and in business installations throughout the country. For years Jeff has published a calendar celebrating the beauty of The New England country-side in all seasons. All of the proceeds from his New England Reflections Calendar have gone to support the Pulmonary Rehabilitation Program at the Cheshire Medical Center. Jeff has a strong commitment to sharing his excitement about the special beauty of our region and publishes a weekly blog about photography in New England.

Sunday, January 19, 2014

Diffraction & Best Lens Sharpness

As a landscape photographer, I am frequently striving to capture the maximum depth of field possible, but as is true of all photography, compromises need to be made on the path to the sharpest images.  The widest DOF is obtained at high f stops (small apertures), but with ever smaller apertures diffraction begins to affect sharpness, making images progressively softer.

Yikes, Physics


Diffraction is a property of light related to its behavior as a wave.  Light passing through a lens does not focus sharply to a point, but spreads out as it is bent around the hard edges of the iris. The result is a soft bull’s eye, which is called the “Airy disk” and results in a softening of the detail in an image.  The name “Airy disk” may seem remarkably fanciful, especially originating from optical

Airey Disk:Wikipedia
engineers, but it does not come from its soft airy appearance.  The fact is that the guy who discovered the disk was named “George Airy”.  Diffraction is an innate property of light and not a defect in the lens.  It is present in even the most precisely constructed and expensive lens and grows worse as the aperture becomes smaller.  A few weeks ago I demonstrated the star burst effect created by diffraction on Christmas lights when small apertures are used.  The effect is minimal when the lens is wide open, but other optical defects such as spherical aberration, diminished sharpness at large apertures.  The balance of these competing effects means that the sharpest f
Starburst Effect
stops tends to be those a few stops smaller than wide open.  A lens is “Diffraction Limited” at the f stop beyond which the image begins to soften.   This is a property of the lens and not the camera, but since a lens’ Airy disk is the same absolute size on any camera, the effect tends to be relatively larger and therefore more prominent in cameras with smaller sensors and with higher resolution.   It is great to have all those pixels, but crowding all those smaller elements on the sensor means that the lens will be diffraction limited at a wider f stop.  Physics sucks doesn’t it ?  The properties of every lens/camera combination are different and the only way to determine optimal sharpness is to test it.

The Test

Fortunately, testing lens' for their sharpest f-stop is not difficult.  You start with a target that is flat and has sharp detail.  I used an antique map of Vermont and New Hampshire.  I taped it to the glass on a photograph hanging in the kitchen and then set my camera on a tripod, aligning it so that the plane of the sensor was parallel to the target. I precisely focused on the map using the camera's Live View and used mirror lock-up and a cable release to avoid any vibration. With the camera set on aperture preferred, I  recorded a series of images covering the full range from wide open to the smallest aperture.  The result was a collection of images that I could quickly scan to find where image sharpness began to break down as the f stop increased.

The Results

Actually I was pleased to find that the loss of sharpness at small apertures was not as bad as I had expected.  I was able to identify the optimal f stop (usually between f/10 & f/16), but I also got a feeling for how far I could reasonably push the aperture when I needed more depth of field.  For my 100mm Macro, I found that the images were sharpest around f/8 - f/14, but that I could still get reasonable results up to at least f/22.  It is important to remember that this analysis does not take into account the power of sharpening algorithms to salvage sharpness when the results are marginal. 


Landscape Dilemma

So what can we do when extreme depth of field is needed?  Sadly I can’t afford a tilt-shift lens, but, now that I know how far I can stop down before diffraction significantly rears its ugly head, I can more intelligently balance the impact of DOF vs. Sharpness and I can apply post processing sharpening to correct some of the problems.  This is also a situation where focus stacking becomes extremely valuable. Multiple images at lower (and sharper) f stops, progressively focused through the scene, can be stacked and blended to get deep DOF with consistent sharpness.  The digital camera once again defeats the apparently immutable laws of physics – take THAT Newton!

Photography is always a matter of compromise as our artistic vision collides with the limitations imposed by the physical properties of light, optics and camera sensors.  How these limitations are balanced has much to do with the outcome and knowing the most about the capabilities of your equipment is the key to striking the best balance.  Testing your lens' for their optimal sharpness is just one piece of the necessary homework required to get the most from your equipment and the best expression of your vision from the digital Camera.


  1. At what focal lengths would you test a telephoto lens (18-200mm, 70-200mm and 70-300mm)

  2. Best camera brand
    Compact Cameras Review offers you the most trusted reviews on some of the hottest brands of cameras. From Compact to DSLR, we have got you covered!

  3. Hello, this weekend is good for me, since this time i am reading this enormous informative article here at my home.
    Best Camera for Wildlife Photography

  4. Getting it Right in the Digital Camera Since my days of creating hand-made prints from old Polaroid pictures, I have spent much time thinking about how to make digital images better for you. Proposal Writing Help These are some of those best practices and tips: Use your camera's focus peaking functions – If shooting full frame cameras (think Leica M) or APS-C sensors that don't get focused during recording, try using a PDAF function such as f/1+ lens' at focal lengths higher than 1″. This will ensure sharpness between frames even when there is no viewfinder attached (it does not take up enough space).

    1. Presenting the finest and trending collection of mens aviator bomber jacket for men who are seeking all-new leather jackets at discount of 50% and Free shipping. Thank you for this great post!

  5. It's quite interesting and informative post, as a professional linkedin profile writer I'm also going to write some educational articles for students and job seekers.

  6. This is a good idea for people who actually have some questions or inquiries about this topic. I am so excited to see the discussions that will be made on this thread regarding taxes. learndash consultation I have to say that this kind of topic should really be discussed thoroughly to people who finds it helpful so that there won't be no confusions anymore.

    1. Great said, this is really a good post and quite interesting thanks for sharing, I'm also starting writing articles on the best and affordable women shoes with new and trendy designs.

  7. I will always let you and your words become part of my day because you never know how much you make my day happier and more complete. There are even times when I feel so down but write my college paper I will feel better right after checking your blogs. You have made me feel so good about myself all the time and please know that I do appreciate everything that you have

  8. The very next time I read a blog, I hope that it won’t fail me as much as this particular one. I mean, Yes, it was my choice to read through, however I genuinely believed you would have something help with assignment helpful to say. All I hear is a bunch of complaining about something that you could fix if you weren’t too busy searching for attention.

  9. Stunning site! Do you have any accommodating clues for trying essayists? I’m wanting to begin my own site soon yet I’m somewhat lost on everything. Would you prompt beginning with a expert service uk free stage like or go for a paid alternative? There are such a large number of alternatives out there that I’m totally overpowered .. Any thoughts? Welcome it!

  10. I believe this will help your website become more organized because you have decided to set a part on this site for the inquiries regarding tax and as well as the helpful discussions. To be honest, this is one of the few sites that are doing this kind of help with essay writing strategy. Also, I think that this will not only benefit your clients or the potential ones but you most especially because you will be able to see the questions easier.

  11. Impressive!Thanks for the post. This is the article that might be a great help for you where you can learn morse code language either of two systems for representing letters of the alphabet, numerals marked by an arrangement of dots, and dashes. To know more visit it. Thank you!

  12. Although it's the era of smartphones with great and amazing camera features and people are less going towards digital cameras. I've also bought I phone x to capture the pictures of my louis vuitton varsity jacket for my e-commerce store.

  13. Good day, my friend! We appreciate your time and effort in creating such a great essay. Please continue to write.
    hitman site