06-11-2022 04:32 PM - edited 06-11-2022 04:33 PM
Does back button focus in Live View and touch screen focus in Live View produce the same focus sharpness?
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06-12-2022 12:41 AM - edited 06-12-2022 01:16 AM
@bpittelman wrote:"I generally shoot studio portraits with strobes with autofocus set to single point. I shoot with a 50mm or 85mm at 5.6 or 8 and shutter at around 200, focusing on the closest eye. I often lose great shots because the eyes are soft. I try using a tripod, but I still miss some good shots. I have read that the live view focus of the 5d MIV is better than through the view finder. Not sure if that is true, and if so as long as it is on live view does it matter if I use the back button focus, the touch screen focus or the shutter release button"
Personally, I use the viewfinder on the 5D mark IV and get sharp images, but I don't see why BBF wouldn't be effective in LV. I've never really compared it to live view, but theoretically, live view should be more precise. Keep in mind that these are two different methods of focus. The viewfinder uses a different path because of the mirror and is sent to a separate sensor in the floor of the camera to acquire focus. I never can remember what type is used (contrast detection or phase detection) but I think it's phase. In live view, focus is set by the main sensor itself using phase detection dual pixel auto focus (DPAF) and maybe contrast, via a direct path through the lens. At any rate, it is reported that live view gives more accurate focus, but I cannot confirm that.
From your description "I often lose great shots because the eyes are soft", you may need to do a "micro adjustment" with the viewfinder. This is not needed with live view because of the way it acquires focus. It's at least worth the effort of a test. I have many lenses and have only had to adjust one for front/back focus. Another thing you might give a shot, and I'm a little hesitant to mention it given your preferred apertures, is trying some Dual Pixel Raw shots so you can micro adjust your focal plain and maybe bring your eyes more into focus. The drawback (maybe) is you have to use DPP 4 to access DPR adjustments, but you can export to PS from DPP. It also doubles the size of you Raw files. I've used it and it works, provided you understand it is a "micro" adjustment. It also works best with wider apertures (narrow DOF). I've used it on occasion for portraiture and birds to make eyes more clear and it has some other features to do with bokeh.
Newton
06-11-2022 06:09 PM
Quite a bit depends on what you are using in terms of lenses, apertures etc and how many focus points you are using. If you want precise focus, then I would recommend single-point autofocus, zoom in and let the autofocus lock on.
If you want to then use live focus with focus highlights to identify what is in focus. Again, if you have a decent DoF, it won't be too challenging. However, if you were doing some serious macro work then using live focus, as magnified as possible would be a good idea.
06-11-2022 08:35 PM - edited 06-11-2022 08:37 PM
Hi Trevor,
Thanks for the response! I generally shoot studio portraits with strobes with autofocus set to single point. I shoot with a 50mm or 85mm at 5.6 or 8 and shutter at around 200, focusing on the closest eye. I often lose great shots because the eyes are soft. I try using a tripod, but I still miss some good shots. i have read that the live view focus of the 5d MIV is better than through the view finder. Not sure if that is true, and if so as long as it is on live view does it matter if i use the back button focus, the touch screen focus or the shutter release button
06-12-2022 12:41 AM - edited 06-12-2022 01:16 AM
@bpittelman wrote:"I generally shoot studio portraits with strobes with autofocus set to single point. I shoot with a 50mm or 85mm at 5.6 or 8 and shutter at around 200, focusing on the closest eye. I often lose great shots because the eyes are soft. I try using a tripod, but I still miss some good shots. I have read that the live view focus of the 5d MIV is better than through the view finder. Not sure if that is true, and if so as long as it is on live view does it matter if I use the back button focus, the touch screen focus or the shutter release button"
Personally, I use the viewfinder on the 5D mark IV and get sharp images, but I don't see why BBF wouldn't be effective in LV. I've never really compared it to live view, but theoretically, live view should be more precise. Keep in mind that these are two different methods of focus. The viewfinder uses a different path because of the mirror and is sent to a separate sensor in the floor of the camera to acquire focus. I never can remember what type is used (contrast detection or phase detection) but I think it's phase. In live view, focus is set by the main sensor itself using phase detection dual pixel auto focus (DPAF) and maybe contrast, via a direct path through the lens. At any rate, it is reported that live view gives more accurate focus, but I cannot confirm that.
From your description "I often lose great shots because the eyes are soft", you may need to do a "micro adjustment" with the viewfinder. This is not needed with live view because of the way it acquires focus. It's at least worth the effort of a test. I have many lenses and have only had to adjust one for front/back focus. Another thing you might give a shot, and I'm a little hesitant to mention it given your preferred apertures, is trying some Dual Pixel Raw shots so you can micro adjust your focal plain and maybe bring your eyes more into focus. The drawback (maybe) is you have to use DPP 4 to access DPR adjustments, but you can export to PS from DPP. It also doubles the size of you Raw files. I've used it and it works, provided you understand it is a "micro" adjustment. It also works best with wider apertures (narrow DOF). I've used it on occasion for portraiture and birds to make eyes more clear and it has some other features to do with bokeh.
Newton
06-12-2022 09:29 AM
Thanks Newton! Appreciate your comments. I am going to test the live view focus in my next session. In the mean time i am going to look into both the micro adjustment, and dual pixel raw. Thanks again!
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