Back to fully manual - some focus questions...

GIlesM · Jul 20, 2016

wow, thanks to everyone. Now I know what focal length is, I can understand how a 12mm lense at f8 or higher produces focus.
The video was very good, it was good to be reminded of things I was taught at least 35 years ago!
It is amazing how years of using fully automatic cameras, has eroded my understanding of photography.

I wonder how many people out there snapping away with their iPhones and fully automatic cameras (yes that does still include me) do not understand what is happening? not that many I guess, here is the thing, does it matter? To the vast majority probably not, but I like to try and understand what is going on and switching back to manual has been a real lesson!
Thanks again to all who contributed.

dennybeall · Jul 22, 2016

"does it matter?"

Only if you want to take something other than a snapshot................

AndyG · Jul 25, 2016

This has been an interesting thread. I enjoyed that video. It helped me understand at a greater level than I already did. For all intensive purposes, when I picked up my 7D and my f/1.4-50mm, I always left my camera in AV and left my lens on manual focus. I wanted to force myself to learn instead of using auto. I've had my camera for roughly 9 months and just recently started using AF, live mode, and AF points. I just recently added a Rokinon 16mm(fully manual lens) to my roster and am looking forward to going on that journey. I plan on using live mode as a backup for focus because sometimes my eyes have a hard time with the viewfinder.

Thanks for sharing that video!

Ysarex · Jul 25, 2016

AndyG said:
This has been an interesting thread. I enjoyed that video. It helped me understand at a greater level than I already did. For all intensive purposes, when I picked up my 7D and my f/1.4-50mm, I always left my camera in AV and left my lens on manual focus. I wanted to force myself to learn instead of using auto. I've had my camera for roughly 9 months and just recently started using AF, live mode, and AF points. I just recently added a Rokinon 16mm(fully manual lens) to my roster and am looking forward to going on that journey. I plan on using live mode as a backup for focus because sometimes my eyes have a hard time with the viewfinder.

Thanks for sharing that video!

Don't get too excited over that video. There's some accurate info there, but the explanation for how DOF works (toothpaste) is pretty bogus. Failing to make the connection between subject distance and focal length is also a major omission. (Magnification is a function of subject distance and focal length. At a constant magnification DOF holds constant.)

Back to the toothpaste visuals: with your 7D and 50mm lens focused at 20 feet and set to f/11 you'd have DOF in the "toothpaste tubes" of 7 feet before the focus plane and 21 feet behind the focus plane -- 3 times as much in the back which doesn't jibe with the explanation or visuals.

Joe