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How auto focus works

Ok. I will admit when I got my Sony a9 I feel in love with the facial tracking. With my Canon Mark III I was shooting with manual focus and while it was ok… it was a pain. But one thing I really dislike about the auto focal tracking in video, especially with wide open apertures, is the seeking. The camera locks on pretty well..ok… more then pretty well, but there are times when something comes in front of the subject or the camera wants to focus behind the subject for a second. Compared to the auto focus in my Mark III the Sony A9 is well… WELL…. advanced. The camera doesn’t have a fit when it searches. Typically it smoothy refocus. So that is a huge bonus…but… I still don’t love it when I want it to stay put. Part of it is I am shooting wide open and the other issue are subjects who erratically move

In older and newer camera’s when you  hit your shutter button half way down your camera snaps to focus on the focus point. Many newer cameras have added facial recognition to their tool bag. It is pretty awesome to register faces of your kids so even the camera will seek them out and make their face a priority. For stills, focus was pretty good regardless if you have the newest model or not…although newer models do have improved focus.  For video though, if you hit the shutter half way down while recording it you see the focus work to seek and find focus. It isn’t pretty and isn’t usable footage. We always tell our students when videoing to not tough the shutter button during the key moments. If they want to grab focus at the beginning of the recording …great..but it will be footage they will have to most likely trash.

Auto focus in newer cameras like the Sony A9 (or really any of the Sony Alpha line) is light years ahead. It kind of glides into focus. During the recording it will track a moving face (and body) as it comes closer to you or side to side.  Typically it does it beautifully. But it can be tricked and since it is looking for faces there are times when a face moves out of the frame or is obscured and the camera will lock on to a new subject… sometimes resulting in unwanted footage.  For the most part it works great and is almost intuitive.


Why use a manual focus lens?

In steps Zeiss. Again, I liked the tracking capabilities of my Sony for the most part. But I did notice there were times my focus would change when I didn’t want it to. Shooting with a manual lens gives you complete control. At first it is scary and  you think you are going to miss the important shots. Well…guess what…you may…but you may miss important shots with an auto focus lens to. It all just takes practice.  In the video below I purposely had branches and limbs go in front of my daughter’s face. This would have most likely caused my camera to shift focus to the limb in front. I shot this video at 2.8 which was the widest the lens would go.

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First off, this lens is lighter then my Batis 85. There is a hard stop on the focus ring which means you won’t just keep spinning and spinning.  It stops so you know to go the other way. With auto focus lenses that isn’t the case..you could just keep spinning. I have really really enjoyed this lens.

To make focusing a million times easier I turn on focus peaking. I set that sucker to high and have it on red. As I turn the focus ring anything in focus it outlined in red.

To really try this out I took my very fast and very erratic daughter out and had her climb a tree. I originally thought, this lens would be great for photographers who can take their time, like to fine tune…but not for taking pictures of quick kids. But no… it was great. That being said, do I need to  practice more..yes. Did I get focus 100% of the time..no. But then again, do I get focus 100% of the time with auto focus..nope.

I do have to say that my daughter had some chewy candy while helping me…mistake. I had really pretty footage of her chewing..haha. So I tried to cut it out…the things mom’s have to deal with.

I am putting this lens set on my list. I want them all. I never never never would have thought I would have said that. But I like loved the video with it. This Loxia 85’s widest aperture is 2.8 and I loved how the video looks. It was a great weight to hand hold as well. I even felt like I could fine tune my focus while videoing, which I could not do with my canon. I loved how the focus never shifted. It truly had a more cinematic feel.  Elements come in and out of focus without and sudden shifting. We often shoot in nature and there is always a branch or leave that would grab the focus way from the sweet face we are videoing or photographing. Maybe I am a control freak, but for video… this is the way to. I even set up my camera to quickly toggle between auto and manual focus while videoing because I loved the way it looked so much better. With Sony’s camera body stabilization and Zeiss’s lens stabilization I feel like I have refine my focus while videoing. I never NEVER would have tried that before.

And did I mention…SHARP… yes  yes yes! This is a close close close up of the first image in this post. wow!

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Here are my top tips for shooting with manual focus lenses

1. Use focus peaking on high and in red. This will help you quickly see what is in focus.

2. Shoot a little bit more closed down to get more in focus. This is especially true for video where you have moving subjects.

3. Use your body by moving forward or back slightly to refine focus vs. using the focus ring. You can do this both when shooting stills or video. It is great when videoing so you don’t add additional camera shake when you touch the lens.

4. Pre focus the action. If you are planning a video shot (or even a still shot) where your subject is going to come in to focus or is doing an action like popping up into your shot, have them stand where they will end up, focus  on them, and then have them move into their starting position.  If all goes well, they should end up in focus.

5. Practice. You need to get your hands attuned to your lens and the focus ring.

6. Use the distance makers on your lens. You lens has numbers in feet and meters. These are super important to help you gauge how far the “in focus” range is.

7. Be ok with beautiful out of focus footage. I am serious. I would rather have  footage that moves between in and out of focus over having my focus search or catch the background behind my subject. In stills focus is pretty important for most shots, but in video soft out of focus motion is stunning.

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