Diffraction or Aberrations - Pick your Poison

Greetings all!

I hope everyone had a more relaxing weekend than I did! I did not stop going until 8PM on Sunday evening when I wrapped up my last lesson - a “golden hour” lighting workshop that I did at a local cemetery. The weekend started with a two and a half hour Pzoom which was definitely among the best sessions that I have had the privilege of hosting. The meeting was jam-packed with interesting and engaging discussions, covering a broad range of topics. An excellent Tangent, hosted by Larry, was also well received and packed with useful information. The rest of Saturday was filled with all the stuff one has to do to keep the business open - none of it particularly fun, but all of it very necessary.

A buckeye at rest

On Sunday I worked on projects that have been somewhat neglected during my European travels, and finished a couple of clients jobs that were due. In the afternoon, after having my regular weekly Zoom meeting with my children, something I never miss, I got to meet one of the friends I have made through this channel. Julie was on her way north on an astrophotography mission to the Great Lakes, but she was kind enough to stop for a quick tour of the bunker and a nice long chat that was unfortunately cut short so that I could make it out to the cemetery in time for the workshop. Getting back to the studio at sundown, I promptly fell asleep at my desk, sedated by too much Chinese takeout and a less-than-scintillating YouTube video about AI and the end of the world.

an owl, i do believe

So you can imagine my surprise when I woke up, early on Monday morning, ready to get to work and with a great idea for the week’s livestreams! During the Sunday workshop I had talked a lot about lenses and how to use them. From the questions I was getting it became clear that there are a couple of lens-related topics that seem to be particularly challenging for many photographers. Both of these subjects are extremely important to understand but both have enough physics to make them tricky to grasp. I am, of course, talking about the two sides of the same image-quality coin - diffraction and aberrations. Both of these topics - the first a physical phenomenon and the second a design feature of lenses - can play a huge role in final image quality but both require a good understanding of the underlying science if we are to be able to control them effectively.

One pice of cover art for two streams - how economical!

On Tuesday, in Macro Talk, at 8PM, I will lay out the important facts of diffraction and give just enough of the physics to help you understand the advice we give for preventing diffraction softening. I will present some graphics that I hope will give you a very useful way to think about this physical phenomenon so that you can understand why we give the advice that we do. Some of this material may be new to you, while some may be familiar, but I hope to leave you with a new way of thinking about diffraction that will translate into better images almost immediately. Here is your link to the Tuesday Livestream… https://youtube.com/live/uQNFyq6a7xI?feature=share

Thursday’s Macro Talk Too, at the usual time of 2PM, will look at the other crucial aspect of the lens, aberrations. One fundamental difference between diffraction softening and the quality issues caused by aberrations is that the former is result of physics and the latter is the result of lens design. Or put another way, an aperture closed down to f/22 will cause softening in even the best lenses, but if you want pictures that have no chromatic or geometric aberrations at all, just buy a 150mm Printing Nikkor and use it at 1:1. But for most of us, that is not an option, so I am going to talk about all the different types of aberration, how lens design can overcome them, and which ones are most important to address in macro photography. Here is a link to that Livestream… https://youtube.com/live/CGwhTV-7lV4?feature=share

A wee baby gator

After these two streams I expect that you will be in a much better position to choose the best possible lens for your use case and to know exactly how to use it to get the highest quality images.

Coming up on Saturday we have another AfterStack - I have not yet decided on a topic for discussion but am leaning towards a look at all the new features since the last time we looked. Whatever we decide, the show kicks off at 10AM and goes until we run out of stuff to talk about. Here is your invitation to the party …

Allan Walls is inviting you to a scheduled Zoom meeting.

Topic: AfterStack 29

Time: Aug 23, 2025 10:00 AM Central Time (US and Canada)

Join Zoom Meeting

https://us02web.zoom.us/j/6916802815?pwd=TS9tZi9ZL1NXeVUvOUF4eTg5YjdlZz09&omn=8466892658

Meeting ID: 691 680 2815

Passcode: 678122

Join instructions

https://us02web.zoom.us/meetings/84668926580/invitations?signature=1RHheSwoh4HtZ0V6VkMMBNeG-TiTIUaAr9DxSS7DHhw

One of those crystals that I don’t have a record for - so will probably never find again!

I am going to leave it here for now - I have a lot of work to do to be ready for this week, and I really want to get out and take some pictures, preferably before I forget how it’s done!

Have a great week and hope to see you around!