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Old December 10th, 2010, 08:48 PM   #1
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how hard is focusing with DSLR? not using a follow focus

How hard or easy is it to focus video using a DSLR with video? By just using your hand not a follow focus. Does it make it easier having a higher F stop?

Im asking because I like the new Sony a33 that has auto focus with video, but the photos are not as sharp as the Sony a580 that does not have auto focus.
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Old December 10th, 2010, 08:58 PM   #2
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so does the Nikon D7000; but its the slower (contrast detect) type of AF during video. It depends a LOT on the lens; does it have a nice, fat focus ring? what is the focus ring ratio? is it a smooth focus ring or is it notchy or vague?

I would say the answer to your question depends on the lens; for instance i use Nikkor (Nikon) AI/AF lenses and Canon FD lenses with NO follow focus all the time, but they have a lot of smooth, linear resistance. They feel like you are twisting the focus barrel over greased bearings, or like a nice fluid head tripod. If i try to use a modern EOS or G type Nikkor, the focus ring is fast and rough; easy to ruin a smooth pull.

I would not worry much about the AF systems on DSLR's or near-DSLR's; its all contrast detect AF which is slow, 'hunts' in and out of focus awkwardly, and distracting in practical shooting. Most of the time you will be manually focusing anyways, or prefocusing (sports/live/action events) and cranking the barrel to the correct spot.
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Old December 10th, 2010, 11:25 PM   #3
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It's not hard to do it without a FF. Just not as comfortable. I think it also provides a slight buffer when you move your hand off and on it which would normally cause a slight bump in the video. The gear ratio helps with precision too. Since I switch between several lenses it provides a consistent feel. Plus they look cool!
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Old January 19th, 2011, 04:57 PM   #4
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I second these gentlemen.

Especially on the D7000, it totally depends on which lens you're using.

I traded in my kit 18-105 for an 18-200 and for stills and grab shot video it's fine.

But I will not follow focus on either lens by hand - the manual focus ring has no end stops and is very plasticky and sticky/unsmooth/cheap on either of those lenses.

Any one of my older AIs Manual focus metal barrel lenses will outperform any plastic ring lens on a manual focus pull any time. So that added smoothness, even on my ancient 35-70mm macro zoom, means the shots coming from it outperform those coming from a much more expensive lens - but with the plastic focus ring.

So for my money the next move up will be, apart from primes, the D series AF-S lenses. Pro lenses (gold ring) but one generation earlier than the G series / plastic barrel lenses. For focus pull shots.

Otherwise, not - for instance, the Tokina 11-16 will be on my list regardless just because it's so wide.

And I'll probably combine that with the street sweeper zoom for stills and the occasional grab shot where you go out and you don't know what you'll be shooting.

For those shots it's pre-focus and meter with the mirror down, then switch to live view and shoot. At that point I'm usually just fixed on getting the shot, and if the subject moves, rough focus bumps on AF-S are usually good enough.

Obviously those kinds of moves only work for certain styles of film making (kinda sorta LA Law style MTV monkey-vision shots, I call them), so definitely YMMV - mine does, every day.

So even though I do have FF rings and a rig for all my lenses, plastic or not, I'll only really use the FF rig for the metal ring zooms and the primes.

If I'm going to FF on the plastic ring lenses, I'll just pull the ring itself stills camera style, or I'll attach a gear and hand-pull focus on the gear ring. For me, it's just smoother that way.

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Old January 20th, 2011, 01:08 AM   #5
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I have to add that the Sony SLT cameras do not have contrast AF but fast smooth and accurate PHASE detect AF.

It makes a world of difference.

Just watch this video
and tell me if this can be done with any other camera of any kind (hint, it's all shot at f2.8 on a 70-200 handheld).

It overheats so it cannot be your main camera at a wedding but for those moving shots it should be the perfect tool.

I'm getting myself one in a couple months just before the season starts (waiting just in case an improved a77 shows up).
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Old January 20th, 2011, 01:53 AM   #6
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This is good. But... at 2:50 you can see that the problem of using AF is that if your subject moves off-center, the camera will re-focus on the background which is ok for most things but it is the primary reason that even with a deep DOF, small chip camera, why I use manual focus. I also don't like to hold the subject in the center of the frame all the time. Now in the case of DSLR, which are notoriously tough to maintain focus especially at open apertures, maybe this auto focus issue is worth the trade off. Personally, I like that Manual focus is difficult, because if it was easy, anyone can do it... : )

Thanks for posting the video
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Old February 20th, 2011, 01:05 AM   #7
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Focusing with a DSLR while filming is pretty hard. Especially with the modern Canon lenses.

I use a Canon EOS 1D Mark IV and have been trying my hand at filming since Jan 2010. I have been photographing for the last 19 years and started with manual focus SLRs. So I am not new to manual focusing.
However, I find it pretty hard to get the focus right while filming, as the focusing ring is not designed for smooth play. When you are shooting with super teles like 400mm f2.8 L IS with a 2x converter, the shallow depth of field due to the focal length and the large sensor makes it extremely tough.

Canon has announced its new series of Super telephoto lenses with a smoother focusing ring. Lets see how it works out.

Using an external LCD viewfinder helps a bit. However, the problem remains.

Having said that, while filming I want a good and fast autofocus to acquire focus initially and then do the manual focusing later. I don't want the autofocus to pick up the swaying grasses and miss the tiger.

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