Let me start with your second question. Lens manufacturers adjust the autofocus mechanism so that optics produce an image that is in focus at different apertures and distances. However, for some unknown reason, a user may find that when focusing a DSLR through the reflex system, not live view, even a brand new lens may not focus properly. You can expect this over time with a lens as the mechanical parts wear and fall out of adjustment. In these cases, the lens's sharpness depends upon the electromechanical mechanism that controls how the glass elements focus. Unless you compare the sharpness of your lens against another lens, previous test shots, or a standard, you may never notice the declining sharpness.

Calibration is the process of comparing the performance of your lens's focusing accuracy against that of an objective standard. If FoCal finds the performance can get better, then it will perform a microadjustment to the lens. FoCal tells the camera's onboard computer or the firmware in the lens (I do not know which) how much the lens must compensate for the wrong focusing.

I hope this answers your question without getting to technical.

I used this to calibrate my lenses several years ago but am now upgrading to the newest version. In addition to running on a desktop computer, it now runs on Android and IOS. It can also connect wirelessly via WiFi. The price is great, $99.88, down from $135.88. The simpler version is $89.99. A great price for an excellent product.

Interesting terrain done well. I am glad you did this as a panorama. That really captures the bareness. I noticed near and far seem in focus. Did you use focus stacking?

Thanks for posting.

Interestingly, PS's shake reduction is gone from 2023. I used it a lot and wonder what has replaced it.

Rongnongno, how did you merge the masks? Did you have to switch clouding masking off to get the local masking?

Bridges, this is a wonderful shot. Off-topic but certainly lovely to see. Thanks for posting. PS How much post-processing did you do?

A little haiku to start the day. Thanks.

Never too late learn.

Might this not have been a candidate for focus stacking?

Though I am not ready to take the plunge, my 80D is a remarkable camera. For someone with a limited budge but wanting to move up, this is an excellent way to go.

This is truer than ever before for two reasons. Computerized cameras get such great exposures and colors. The vast majority view pictures on a small hand-held device only. For them, pictures are no more than a mere snapshot. Meaningful pictures get lost in hundreds of forgettable ones on their device.

I have spent great time and effort to improve a picture making a ho-hum snapshot into a memorable picture that prints nicely at 8x10. They could care less but I am exciting and pleased despite the time invested and their indifferent response. But I am probably the only one who has experienced this....

The odd numbered ones really stand out for me. One: the lovely sky, the pretty water. Three: the drama. Very reminiscent of the style of the 30's and 40's. Very powerful. Five: that whimsical shack, hut, building or whatever you want to call it. I can imagine a guy with a strong brogue, suspenders, checkered red shirt, and long beard living there. Thanks for posting.

The real challenge is how you are going to market them. Without aggressive marketing, they will die on the vine. Have you considered print-on-demand instead? Good luck.

If you want to see some extraordinary multiple flash pictures, look up O.W. Link and his night time railroad train photos. Artistically and historically interesting, technically great. https://www.incredibleart.com/o-winston-link/

Good subject and pose. Do not like the rendering: too contrasty and miss not seeing all of the cap. Too tightly cropped on the sides.