Author Topic: Dialing in focus for distances / Soft images  (Read 8134 times)

HondaATC

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Dialing in focus for distances / Soft images
« on: January 16, 2014, 06:02:50 PM »
I've played around with magic lantern for about a year now and have had awesome success recording up close, shallow depth of field stuff using it on my T3i, imagery that just makes my jaw drop its so good  ;D

The problem is, for some reason, I still seem to be completely unable to dial in the focus on a broad, wide area. Lets say instead of zooming in and focusing on a specific few leaves of a tree, I want to get the whole branch, or the whole thing maybe after I've backed off 50ft or so. I've tried dialing in with magic zoom and set it to as close as I can get it, but it never looks good on a monitor...Much more like something from a late 90's miniDV than the awesome footage I can make it do up close.

Example; I want to setup in a yard and just capture the trees around a house moving in the wind gently, birds flying around, etc. and it just looks plumb terrible in post. General settings would be 1/60 as recommended iso100-200 and Aperture no less than f8, which I would think would give me a pretty wide depth of field, if that is the problem. I've tried this with a few different lens, 18-55 kit lens, 10-22, and the 50 1.8 and I have the same problem with all of them, so I know its an operator error, just not sure what it is. Especially frustrating since I can get such awesome footage up close - my GoPro's make much clearer footage at these distances somehow.

Do I need to go wider on the aperture? I can post some clips if that' be of assistance.

Audionut

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Re: Dialing in focus for distances / Soft images
« Reply #1 on: January 25, 2014, 06:29:51 AM »
Depth of field is a function of focal length, distance and aperture.  Once you go past around f/6.3 on a T3i you start to suffer from lens diffraction (softness).

You can use an online depth of field calculator to determine correct aperture settings.  With your T3i and 50/1.8 for example, at 50ft (subject distance) you can use an aperture value of f/2.8 to deliver a DOF of 36ft.  That is 12ft in front of subject and 24ft behind the subject as retaining acceptable sharpness.  At f/5.6, your total DOF becomes 114ft.

If your focus is correct, and you DOF is sufficient, the only way to increase quality is with better lenses and camera body.  I suggest you go down the lens route first as it will deliver the biggest bang for your buck.

Frank7D

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Re: Dialing in focus for distances / Soft images
« Reply #2 on: March 03, 2014, 05:43:08 PM »
The other thing is that, if you are shooting H264/mov (as opposed to raw) your image will suffer if it has too much information in it, i.e. a wide shot with a lot of detail, such as tree foliage. The camera's encoder can only handle so much detail per frame before it starts breaking down. That's why a shallow dof close-up looks nice and sharp and your landscapes look less so.

xaled

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Re: Dialing in focus for distances / Soft images
« Reply #3 on: March 03, 2014, 08:57:18 PM »
But why do gopro clips look sharper?
Gopro does not capture raw and the lens are not better than on eos

Rshred

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Re: Dialing in focus for distances / Soft images
« Reply #4 on: March 03, 2014, 11:46:45 PM »
GoPro videos usually look sharper because they use heavy in-camera sharpening. In "Protune" mode the sharpening is reduced so you should see a difference between the standard video and "protune" mode. The gopro is also a constant aperture fisheye that is focused to infinity and has a HUGE depth of field, thus causing (almost) everything to be in focus.

HondaATC

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Re: Dialing in focus for distances / Soft images
« Reply #5 on: April 18, 2014, 11:21:57 PM »
So...can I achieve similar sharpness with my camera in post, or in setup? Its hard to imagine its even possible looking at the clips off the camera. Is there any sort of an inbetween mode for h264 besides raw where I can get a better bit rate that'll preserve stuff a bit more perhaps?

The explanation about there being more data in wider shots and therefore not allowing to capture as much details as close ups makes a lot of sense, but I'd like to learn how to mitigate that as much as possible...

Walter Schulz

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Re: Dialing in focus for distances / Soft images
« Reply #6 on: April 18, 2014, 11:48:34 PM »
Is there any sort of an inbetween mode for h264 besides raw where I can get a better bit rate that'll preserve stuff a bit more perhaps?

Use search for GOP (Group of pictures) and ALL-I here. Not the most popular technique with RAW/MLV available. Is there a dev working on this one? I doubt. Won't be possible to bypass Canon's way to process video data: Sharpening, resizing, noise reduction ...

Ciao
Walter

Photogs and videographers: Assist in proof reading upcoming in-camera help!. Your input is wanted and needed!

HondaATC

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Re: Dialing in focus for distances / Soft images
« Reply #7 on: April 20, 2014, 05:36:53 PM »
Thanks, I'll check those out.

I'm possibly getting into uncharted territory now - but is there a way to basically take the raw capability, and use JPGs instead? Surely that would save a lot of bandwidth, and you'd have a whole lot higher resolution to work with you could scale down to 1920x1080 and perhaps capture the additional detail that way? Poor man's raw sort of? I know there is the shutter lock open option, perhaps I will experiment some more with this myself, I know there isn't enough bandwidth to take 18mp 30 frames per second, but even if you scaled the images down to say 2400x something, It might be an improvement over the stock video encoding?

I'm just really unhappy with the quality in the wider angle shots, and I'm glad to hear this may be a technical limitation moreso than my videography capabilities (which I had been trying to resolve...lol)

HondaATC

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Re: Dialing in focus for distances / Soft images
« Reply #8 on: April 20, 2014, 06:22:27 PM »
Here is a perfect example of what I'm talking about,

at the 2:33-2:37 mark, pause it, and you'll see how there is no detail in anything, its sorta "muddy". In many other shots though, its quite good.

Is that a focus issue, or lack of available bit-rate?

That video was done with the same hardware I have basically, and that is almost an exact representation I keep running into...