In high-quality filters, the thickness of the glass has no adverse effect on picture quality. There are some VERY thin filters that are designed to avoid vignetting on very wide-angle focal lengths. Except for certain wide-angle lenses, some additional distance between the filter and the front element should not cause any issues. Use only high-quality brass adapters and retaining rings

Forgetmenot tip: I am an old guy too and still drag lots of gear to work. Even as a young guy, I wanted to make sure I came home with what I had packed. I didn't want to forget something at the studio or accidentally leave stuff on the location. So, I got in the habit of making lists. I printed out a form with check boxes- in and out.

After a long shoot, especially on a hot day, I am always in a hurry to pack up and get back to the a/c. The list takes just a minute to check off- well worth it, especially nowadays with the process of good stuff.

Murphies law of lost gear- Anythg you lose on a job is usually somethg that can not be replaced, made in "Africa by the Ants", long discotuinued, and has to be custom made at a machine shop at a high cost!

I read you to mean "thicker" as the added distance of the ring between the filter and the lens threads. Although different 'thin' models exist for some filters brands, the diameter of the filter circle has nothing to do with the thickness of the filter, for the same 'model' filter.

Wide angle lenses are most likely to be impacted by a 'thick' filter, and even then, the occurrence is rare.

The only drawback of rings I've even countered is the inability to mount the lens hood with the ring and larger filter installed. This proved enough of an issue, in fact, that I mostly have filters for each of my lens diameters rather than rings and less filters. For a 52mm lens, the rings and wider filters actually form a pseudo hood as well as my oldest lenses at 52mm don't have hoods. Using rings here are a bit more typical in my approach.

it is a hybrid notion. The lens must be set in autofocus (A/M or M/A) and the camera have autofocus on for the focus stacking to work. However you can override the camera function initially by simply turning the focussing ring and watching what snaps into focus in the viewfinder. Do that before engaging the actual focus shift function by pushing the start option.

Now, I strongly advocate learning how to control your camera, and Manual metering is a big part of that. But let's take one step at a time.

With respect to the focus stacking attempts. First of all Affinity appears to have done its part of the job correctly. The real issue is obtaining the slices in camera.

In image #1. You got about 90% of what you wanted. As mentioned the issue is the closest foreground. I think you understand that the D850 asks you what you want as the closest point in focus and then it uses the parameters you set to move out towards infinity. Because the autofocus array does not cover the entire frame it is a mistake to rely on that to set the near point. Instead manually focus on what you want as the closest in focus area. Select an aperture that generates a decent zone of focus, say f8, without getting into diffraction issues. Most reviewers are suggesting an interval between slices around 5, the middle of that slider. When the camera finishes its run review the first and last images to make sure you got the end points sharp. As you do more of this you can refine your settings based on the kind of images you take.

As to image #2. Assuming that wanted everything to be sharply in focus, repeat the foreground comments from above. In addition you failed to get the far distance in focus either. That likely means increasing the number of shots you specify and/or widening the interval range.

Finally, even when you get the camera dialed in for focus stacking, just know that in some complicated images with lots of intersecting foreground elements, it simply may not work without weird giveaway artifacts. And of course, if anything moves, you will experience ghosts!

With respect to the focus stacking attempts. First of all Affinity appears to have done its part of the job correctly. The real issue is obtaining the slices in camera.

In image #1. You got about 90% of what you wanted. As mentioned the issue is the closest foreground. I think you understand that the D850 asks you what you want as the closest point in focus and then it uses the parameters you set to move out towards infinity. Because the autofocus array does not cover the entire frame it is a mistake to rely on that to set the near point. Instead manually focus on what you want as the closest in focus area. Select an aperture that generates a decent zone of focus, say f8, without getting into diffraction issues. Most reviewers are suggesting an interval between slices around 5, the middle of that slider. When the camera finishes its run review the first and last images to make sure you got the end points sharp. As you do more of this you can refine your settings based on the kind of images you take.

As to image #2. Assuming that wanted everything to be sharply in focus, repeat the foreground comments from above. In addition you failed to get the far distance in focus either. That likely means increasing the number of shots you specify and/or widening the interval range.

Finally, even when you get the camera dialed in for focus stacking, just know that in some complicated images with lots of intersecting foreground elements, it simply may not work without weird giveaway artifacts. And of course, if anything moves, you will experience ghosts!

If there is a problem uploading files from LR to Focus Merge in AP (I do have LR but rarely use it for anything anymore, preferring AP) why not upload the RAW files from the SD card to AP Focus Merge, do the Merge, and then export the merged file in whatever of the 11 file formats available in AP you choose to LR for whatever processing you want to do there? That way instead of processing multiple files pre-merge you would only have to process one focus merged file. I don't understand exactly what you are trying to accomplish here and my comments may be off-target. If so, my apologies.

By doing the procedure in this way jpg files would not be involved as best I can tell, unless you choose jpg file in exporting the merged file (the list of availble files is shown during the export process). My preference would be tiff since those files are not compressed and carry more data, although the files are admittedly large. I've found that AP handles very large files in post processing with ease. The end results I get by doing Focus Merges as described above are excellent. Hope this is of some help.

It is not my experience that Raw files cannot be uploaded directly to Focus Merge. Simply click on the New Focus Merge tool after opening AP, then "add", then find the Raw file you want to upload in whatever folder it resides in, and click on "open". The file should then upload to the Focus Merge function. Continue to upload however many files you want to merge and it is then ready for merging. That's all there is to it. When the merge is completed you can export the merged file in several different file formats, including tiff and jpg, but also others.