Focus Stacking and Image Sharpness

Focus-stacked orchid, © Dave Anderson

The June meeting of the Pagosa Springs Photography Club will be held on June 9 at 6:30 PM (Mountain Daylight Time), via Zoom video conference. Our speaker will be Dave Anderson, who will discuss Focus Stacking and Image Sharpness.

In Dave’s presentation, he will discuss the use of focus stacking to maximize sharpness and depth of field in both macro and landscape photography. Focus stacking is the process of taking serial images of an object or scene, with the plane of focus moving through the subject, combined to give an increased depth of field. Discussion will include several factors important for perceived image sharpness such as depth of field, diffraction, lens quality, and visual acuity.  A number of software options for focus stacking will be presented, and the process of stacking in Photoshop will be described. Dave will provide examples of stacked images that succeeded and failed, stacking with unintended consequences, and tips for successful focus stacking.

Club members will receive an email with the Zoom link. Others who are interested in taking part may contact Andy Butler at abutler@mac.com  for the link. Club members may submit up to five images to share and discuss following the presentation. 

The Pagosa Springs Photography Club promotes educational, social and fun interactions between all who enjoy making and viewing great photography.  The club sponsors educational programs and outings to help photographers hone their skills. Membership is just $25/calendar year for individuals and $35 for families. Non-members are invited to attend a meeting to learn more about the club. For membership information visit our website at https://pagosaspringsphotoclub.org/about/ .

March 10 Meeting: Tips & Tricks for Digital Photo Processing

portrait of a Cougar at the Albuquerque Zoo.
Cougar, taken at the Albuquerque Zoo, © Chris Roebuck

The Pagosa Springs Photography Club (PSPC) will meet by Zoom video-conference on Wednesday March 10, at 6:30 p.m. Our speaker will be Photography Club member Chris Roebuck. His topic will be Important tips and tricks for successful digital processing. In the program, Chris will consider both technical and artistic considerations in processing digital photos. Using tools such as Photoshop and Lightroom, he will discuss enhanced mid-tone contrast adjustments, maintaining detail with exposure adjustments, and global color corrections. 

Chris Roebuck has honed his photography skills through a commitment to taking advantage of workshops and other educational opportunities whenever possible, including intensive courses from the Rocky Mountain School of Photography, in Missoula, Montana, and Maine Media Workshops and College. Chris is primarily a wildlife photographer, and hopes to always be a student of the photographic arts. 

This will be a virtual meeting, live on-line, using Zoom video-conferencing. You may participate in the program from the comfort and safety of your own home. Photography Club members will receive a Club email containing a Zoom weblink to participate in Chris’s presentation. Others who are interested in taking part may contact Club president Andy Butler for information, at abutler@mac.com. Photography Club members may also submit up to five images to share with the group after the presentation. This month’s theme is open, so submit any of your five favorite/best photos.

The Pagosa Springs Photography Club promotes educational, social and fun interactions between any and all who enjoy making and viewing great photography.  The club sponsors educational programs and outings to help photographers hone their skills. Non-members are invited to attend a meeting to learn more about the club. For membership information visit our website at https://pagosaspringsphotoclub.org/about/ .

Luminosity & Color Masking in Lightroom, July 8

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Fisher Towers, © Doug Coombs

The July 8 meeting of the Pagosa Springs Photography Club will be held at 6:15 p.m., on-line via Zoom videoconference. We welcome back Doug Coombs, who will give a presentation on Luminosity Masking in Lightroom.  

Adobe Lightroom added the capability to use luminosity and color to target local adjustments using the Gradient, Brush, and Radial tools in 2018 using the “Range Mask”. This enables the photographer to make precisely targeted adjustments to selected areas of a photograph. Think of it as dodging and burning, contrast adjustments, color adjustments and other post processing techniques on steroids. Doug will demonstrate how to use the Lightroom Brush and Gradient tools with and without the Range Mask. We may even distribute a photograph to the audience that Doug will process in Zoom and Lightroom while the audience opens Lightroom on their computers to perform the same adjustments. Everything Doug will show in Lightroom can also be done in Adobe Camera Raw, for those you only own a recent version of Photoshop. For a video tutorial on these controls, check out Matt Kloskowski’s blog post on the subject, at:  https://mattk.com/lightrooms-most-powerful-masking-tools/  .

Doug is the chair and co-founder of the Los Alamos Adobe Users Group in New Mexico and a former chair of the Los Alamos Photography Club. He has been doing photography since high school, worked as a photographer and dark room tech in college, and fell in love with digital photography in 2003. Doug is primarily a landscape and nature photographer, with an affinity for birds and wildlife. He now splits his time between Los Alamos, Pagosa Springs, and a generous amount of travel to various photogenic destinations.

This will be a virtual meeting, live on-line, using Zoom video-conferencing. You may participate in the program from the comfort and safety of your own home. Photography Club members will receive a Club email containing the Zoom weblink to participate in Doug’s presentation. Members may also submit up to five photos to share, following Doug’s talk. Others who are interested in taking part in the Zoom meeting may contact Club president Andy Butler for information, at abutler@mac.com . 

The Pagosa Springs Photography Club promotes educational, social and fun interactions between any and all who enjoy making and viewing great photography. Annual membership dues are just $25. For membership information visit our website at https://pagosaspringsphotoclub.org/about/ 

June Program: From Field to Framed

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Eagle in Flight, © Chris Roebuck

The Pagosa Springs Photography Club will next meet by Zoom video-conference on Wednesday June 10 at 6:15 p.m. Our speaker will be Chris Roebuck. His topic is Highlights from a photographer’s education: From field to framed. In his program, Chris will discuss why he photographs, how he uses the language of photography to tell a story, and how he takes his images from an encounter in the field to a framed print. 

Chris Roebuck has been a member of the Photography Club for several years. He began his digital imaging education nine years ago by attending a community college (Lansing Community College). There, Chris learned Photoshop in-depth. After 2 ½ years he went to the Rocky Mountain School of Photography, in Missoula, Montana, to learn Lightroom. That same year he attended printing workshops at Maine Media Workshops and College.  Chris has continued to attend photographic workshops every year since.  He is a firm believer in continuing education.  Chris takes a philosophical approach to his photography rather than an artistic one.  He is primarily a wildlife photographer, and hopes to always be a student of the photographic arts.

2.3 - MaineFox
Maine Fox, © Chris Roebuck

This will be a virtual meeting, live on-line, using Zoom video-conferencing. You may participate in the program from the comfort and safety of your own home. Photography Club members will receive a Club email containing a Zoom weblink to participate in Chris’s presentation. Members may submit up to five photos to share. This month’s theme is “Animals”. Others who are interested in taking part in the Zoom meeting may contact Club president Andy Butler for information, at abutler@mac.com. 

The Pagosa Springs Photography Club promotes educational, social and fun interactions between any and all who enjoy making and viewing great photography.  The club sponsors educational programs, themed challenges, contests and outings to help photographers develop their skills. Non-members are invited to attend a meeting to learn more about the club. Annual membership dues are just $25. For membership information visit our website at https://pagosaspringsphotoclub.org/about/ .

March Club Meeting: Black and White

Teton Cloudcap
Teton Cloudcap, Grand Teton National Park, Wyoming, © Dave Anderson

The March 11, 2020 meeting of the Pagosa Springs Photography Club will be held at 6 p.m., at The Community United Methodist Church, 434 Lewis Street. Our speaker this month will be Club member Dave Anderson, who will give a presentation on  Black and White Photography in the Digital Age.  

Black & white photography can be useful for emphasizing textures, shapes and contrasts in images, for creating more abstract views of a scene, creating dramatic sky or sky-sun combinations in images, and for architectural and fine art photography. The presentation will discuss different methods of creating black and white photographs, and the use of digital filters and presets to produce black & white images in Photoshop and Lightroom post-processing software, with examples comparing color and black & white versions of the same image.

Dave Anderson has a Ph.D. in Chemistry and worked before retirement as a research scientist on malaria, multi-drug resistant bacteria, disease biomarker discovery, drug target identification and other areas. His photographic interests include landscape and nature photography and occasionally urban and abstract photography.

Club members are encouraged to bring up to five photos on a thumb drive to share with the group after the presentation, if time permits. If you have some black & white images of your own, this would be a great month to bring them! (Please note the new limit of five photos, designed to allow more time to appreciate and discuss the images.)

The Pagosa Springs Photography Club promotes educational, social and fun interactions between all who enjoy making and viewing great photography.  The club sponsors educational programs and outings to help photographers hone their skills. Membership is just $25/calendar year for individuals and $35 for families. Non-members are invited to attend a meeting to learn more about the club. For membership information visit our website at https://pagosaspringsphotoclub.org/about/ .

Print Sharpness

It’s difficult to discuss sharpness without making some assumptions. The photograph itself has to be sharp. That means a good camera and lens, correct focus, steady platform, etc. This discussion assumes that you start with a sharp photograph. And then you print.

As an example, let’s use the Sony A7 II, a 24MP (megapixel) camera, which has a frame of 6000 x 4000 pixels.

Commercial printing (e.g. magazines) is done at 240 dpi. Fine art printing is done at 300 dpi. (Most people can’t see much more than 300 dpi.) At 240 dpi the Sony 24MP camera generates a physical print 25 x 16.7 inches. At 300 dpi the print is 20 x 13.3 inches. (length in pixels ÷ dpi). When you consider viewing distance, however, the further you get away from a photograph, the less dpi you need to create the same illusion of sharpness.

The distance/sharpness is difficult to calculate due to so many variables. But the chart at this website gives you something to go by:

http://resources.printhandbook.com/pages/viewing-distance-dpi.php.

It indicates that at a 24-inch viewing distance, you need 300 dpi to get the maximum sharpness. Yet at a 40-inch distance, you need only 180 dpi to get the maximum sharpness. Think of 24 inches as being about the distance you view a photography book or look at a computer monitor. Think of 40 inches as being about the typical distance you look at a photograph hanging on the wall in a museum, gallery, office, or home.

Using the 40-inch viewing distance, you can generate a 33.3 x 22.2 inch print of a 6000 x 4000 pixel photograph at 180 dpi, and it will look as sharp as can be. But if someone sticks their nose into it (gets closer than 40 inches), it will not look its maximum sharpness.

Another means of determining distance/sharpness is to calculate the maximum viewing distance according to the diagonal measurement of the printed photograph. Some experts say the viewing distance should be 2x, some 1.5x, and some 1x (of the diagonal).

Calculate the diagonal with the formula: c = √(a2 + b2) where a and b are the frame dimensions and c is the frame diagonal. Thus, for a 20 x 13.3 inch print, the diagonal is 24 inches. At the conservative 1x, the viewing distance is 24 inches for maximum sharpness (300 dpi). At 1.5x, the viewing distance is 36 inches. And at 2x the viewing distance is 48 inches. Thus, for these last two distances, you would need only a dpi well under 300 to provide maximum sharpness for viewers.

It’s all very subjective. But one thing is certain. The first consideration of sharpness is how the viewer will see the print. And distance matters.

The next consideration is whether you can improve the sharping because it’s a digital photograph and not a film photograph? For many digital photographs the answer is a modest yes. For some photographs the answer is an absolute yes. Sharping digital photographs is beyond the scope of this article and is also subjective. But you may be able to enlarge a photograph 10%, 20%, or 30% and still retain its inherent sharpness by applying sharping in postprocessing. (However, you can’t take an unsharp photograph and make it sharp with postprocessing.) In other words, just by sharping in postprocessing, you may be able to enlarge a photograph a little without the loss of sharpness.

Another consideration is general enlarging. How much can you enlarge a photograph without noticeably losing sharpness? One of the original guidelines was that you could enlarge about 30% by doing 10% at a time, without noticeably losing sharpness. Today the algorithms are better, but the experts’ opinions are subjective. Some say 50% enlargement. Some as high as 400%. But this is something that depends on the characteristics of the photograph, your enlarging experimentation, and the software you use. You might want to do your experimenting with a small portion of your photograph first before committing to printing the whole enlargement.

You will want to remember that enlarging 2x does not double the frame dimensions. It doubles the area of the photograph. If you double the frame dimensions, you enlarge the area 4x.

Finally, consider the medium. Metal prints can be printed at 300 dpi, although 240 dpi is a typical default for metal printing services. The dpi of inkjet printers is virtually impossible to calculate without a lot of specifications you probably can’t easily get. The dpi for inkjet and laser printers is based on advertising, not on the traditional printing dpi. In other words, a 1200-dpi inkjet printer may print only at 280 dpi according to traditional printing specifications. If you buy a printer, you may want to ascertain the actual traditional print specification first, if available. Likewise, if a photographic service provider uses an ink et printer, you will want to likewise ascertain the actual traditional print specifications.

A word of warning. You can order a 12000 x 8000 print of your 6000 x 4000 pixel photograph, and no one at a photographic service will give it a second thought. They will simply automatically enlarge it 4x as part of their processing. Although they usually have good enlarging software, it raises the question of whether you would rather enlarge it yourself knowing that your photograph will otherwise be automatically enlarged. In other words, just because you can order something, doesn’t mean that it will retain its sharpness to the degree you require for your viewers. You may want to have more control.

What’s my practice? I don’t enlarge anything and don’t worry about sharpness. With my 25 MP camera, this is a practical point of view. Nonetheless, there are always those situations where I need a large print, and enlargement is required. In such cases (rare for me because I print few photographs), I decide how to enlarge based on the factors outlined in this article; that is, I handle each photograph on a custom basis. But if you find yourself enlarging your photographs all the time, you may want to get a camera with more MPs thus enabling you to forgo enlarging so much of the time. The new Sony A7R IV has 61 MPs (35mm type camera) with a 9504 x 6336 pixel frame, and its brand competitors are comparable.

Finally, if you typically crop much of a digital photograph away, you may have a need to enlarge what you have left. In that case, a camera with plenty of MPs is doubly useful to your photography efforts.