„Fix Focus“ and anamorphics

[jpolzfuss]

Hi!

What’s the impact of an anamorphic attachment on the „depth of field“-charts?

Most of my attachments force me use „dual focus“ = to set both the camera‘s lens and the anamorphic attachment to the same distance.
This takes a lot of time, sometimes too long, e.g. when you want to film a passing train that is already approaching.

Most of my cameras have a lens that allows me to focus. But on top, most of these lenses have a „snapshot“ setting where you can use your camera like a „fixed focus“ one. Depending on the camera/lens/brand, it’s usually a special distance between 3m and 10m. Elmo usually calls it „universal focus“, Nizo „red dot setting“, Fuji has „click stops“, … . When looking up these distances in a „depth of field“-chart, you can see that usually everything between 2m and 100m is in focus when filming outdoors on a sunny day. …
Hence the question: Can I simply set both the camera and the anamorphic to this special distance and then work without having to focus?
As the anamorphic attachment only makes the horizontal part wider, it shouldn’t have a negative impact on the „depth of field“ as wider usually means larger „depth of field“… Or is this completely wrong?