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6D + Rokinon 14mm + 720p = Super Grainy

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Tom Wille
6D + Rokinon 14mm + 720p = Super Grainy
on May 27, 2015 at 4:02:45 am

Hi All,

I'm a professional videographer so I was surprised when I imported my last set of footage, which turned out extremely grainy. I was shooting with a Canon 6D, ISO set at 100, with a Rokinon 14mm wide angle lens, which has treated me well at 1080p. I don't typically film in 720p, but I had some high action shots that needed the higher frame rate. I kept the Rokinon's aperture at 2.8 and only changed the shutter speed to account for the daylight - hopefully you can tell that the problem with this image isn't that the subjects are out of critical focus. I've scaled the footage up to 1080p using MPEG Streamclip and I'm editing with Adobe PP CS6 with matched sequence settings.

Anyone have any thoughts? Could it just be the poor (cheap lens)? Would people recommend prioritizing closing the aperture above changing the shutter speed for a sharper look?



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Blaise Douros
Re: 6D + Rokinon 14mm + 720p = Super Grainy
on May 27, 2015 at 3:20:09 pm

I've scaled the footage up to 1080p using MPEG Streamclip...

There's your problem.

When you do this, you're stepping on the quality of your footage not once, but twice. Transcoding it, and upscaling it, are both things that can and will add visible pixelation to your image.

So what you're seeing likely isn't grain, but compression artifacts and/or visible pixels from upscaling 720P to 1080P.

What are you transcoding to? Can Premiere CS6 not take the native files from the camera? You want your transcoded files to be as close to the original settings as possible. Make sure, too, that the framerate is the same.

I would suggest transcoding to a 720P file, and letting Premiere handle the upscaling, or better yet, work in a 720P sequence and downscale your 1080P footage.


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Tom Wille
Re: 6D + Rokinon 14mm + 720p = Super Grainy
on May 27, 2015 at 3:49:31 pm

Hi Blaise -

Thanks for your response. I've always been in the habit of using MPEG Streamclip for transcoding all of my footage because I also use FCP 7 to be able to edit/render two projects at once - but I understand I don't *need* to for PP.

Before making this post, I did some testing with bringing in the raw 720p 60fps shot into PP and it still has that soft feel like it was shot in 420p or worse. I did exactly what you said, new sequence that matches 720p 60fps and watched it at 60fps and also slowed down to 24fps. In any case, I'll natively import all of the footage like you said for a better workflow, however for future projects I'll need to know the root cause of why the footage doesn't look crisp.

Do you not think it has anything to do with the lens? That's kind of the common denominator to all of the problems, but I've never heard of that being an issue for anyone before.


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Blaise Douros
Re: 6D + Rokinon 14mm + 720p = Super Grainy
on May 27, 2015 at 6:39:32 pm

The Rokinon 14mm is certainly no Zeiss prime. It is pretty soft. But it's not going to cause pixelation. I mean, 720P is inherently softer than 1080P footage in general, and especially when you're downscaling it on a DSLR sensor. Does it respond at all to software sharpening?

Without seeing an example clip, it's hard to say. Can you throw one up?


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Tom Wille
Re: 6D + Rokinon 14mm + 720p = Super Grainy
on May 27, 2015 at 8:41:15 pm

I usually have very crisp video so I never venture into software sharpening. I've played around with some of the effects in PP and they all make it the footage look fake.

I've uploaded a sample shot below. This is the raw 720p 60fps footage which is matched to a sequence and then quicktime exported. I had the lens at infinite focal range (it has options for 1 feet, 2 feet, 3 feet, and infinite).







If you have any software sharpening advice that would be nice, but I'll be honest I haven't looked into it that hard so I don't want to waste your time when I can google the answer myself!


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Ryan Holmes
Re: 6D + Rokinon 14mm + 720p = Super Grainy
on May 27, 2015 at 8:14:28 pm

[Tom Wille] "Do you not think it has anything to do with the lens? That's kind of the common denominator to all of the problems, but I've never heard of that being an issue for anyone before."

Tom the Canon 6D is notorious for soft video. The Rokinon 14mm is a great little lens. What you're likely experiencing is the bi-product of upscaling soft, moire footage. So the way Canon DSLR's get a 20MP image sensor down to a 2MP HD image is by a process called "line skipping." Line skipping is sampling various "lines" or pixels in order to achieve the image you see on your screen. The problem is that this approach almost always tends to produce a soft image with a high moire effect (tight patterns appear to crawl).

DSLR's as a whole don't shoot "crisp" video pictures because they are either line skipping or binning to get the sensor down to HD resolution. Compared with a dedicated video or cinema camera like the Canon C300, which is taking an 8MP image and downsampling the whole image to HD. So you tend to get very sharp content because it's not cheating it's way down to HD. To your DSLR I would expect that you'd see better (i.e. sharper) results in 1080 than in 720 since the line skipping won't work as hard to get to 1080.

If I can be frank, your lens is fine. It's the DSLR body that is the problem. Shoot the same scene, same lens with a C100 or C300 (or Sony FS7, Blackmagic URSA, etc) and you won't see this problem. Canon's DSLR's have video added as an afterthought. The technology they use (and Nikon) to create that HD image makes a bunch of sacrifices. Yes, they shoot video. But that video is far from ideal. Do a little exploring on the Internet and you'll understand more of the downsides to DSLR's.

https://fstoppers.com/video/canon-6d-showing-hideous-moire-problems-video-4...

http://filmmakeriq.com/2012/12/canon-dslr-full-frame-shootout-between-the-c...

Ryan Holmes
http://www.ryanholmes.me
@CutColorPost


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Tom Wille
Re: 6D + Rokinon 14mm + 720p = Super Grainy
on May 27, 2015 at 8:47:18 pm

Hi Ryan,

Most of what you posted I already knew, but I did learn something new about the line skipping, so thanks for that.

I don't think my problem is the difference in quality between Canon 6D vs. cinema cameras since the 1080p output does me and my clients fine so far. We just aren't big enough to be investing in cinema cameras yet. I love the 6D's video output in 1080p when I take into account how small and flexible the camera is (the main perk of DSLRs). I'm just frustrated at the difference between 1080p vs my 720p footage that looks like 420p, not 720p.

Also, I did notice slight improvements when I used my 24-108mm at 720p on the same set. Still not perfect, but not awful.

I tend to agree with you both, it's likely a combination of lens, camera body, 720p, and maybe being a touch out of focus (overestimating the focal range). I'll ask you the same question, though, would you anticipate a sharper image if I'm shooting outside to close the aperture instead of upping the shutter speed?


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Blaise Douros
Re: 6D + Rokinon 14mm + 720p = Super Grainy
on May 27, 2015 at 9:30:06 pm
Last Edited By Blaise Douros on May 27, 2015 at 9:35:29 pm

Yeah, looking at the video, it's definitely not out of focus. I think you're running into the typical issues with DSLRs--Ryan did a good job of summarizing them, so I won't rehash. I do disagree with him on the lens bit--my experience with that Rokinon lens is that it is soft (although I have also heard that there is some variance between different copies)--so stopping up a little won't hurt your overall sharpness.

The 6D can produce great images when processed right--I often use 6D and 5DIII footage together. But, I ALWAYS sharpen it a bit in post--there is lots of detail that can be recovered. Here's what I would do:

First, your exposure on this shot looks a bit hot, which can make things appear slightly soft. Throw the Fast Color Corrector on, and drop the highlight level slightly. You'll recover some of your sky, faces, and the whole thing will appear to saturate slightly more.

PP (at least, PP CC, which is what I'm using) has a great software sharpener--throw it onto the clip and set it to the 30-40 range, whatever looks best to you. That will sharpen it up, but not to the point that it looks like garbage.

These two effects, in this order, are what I use to dress up 5DIII and 6D footage. You'll be amazed at what a little software sharpening can do to footage from these cameras--I certainly was.

It also occurs to me--you said in your original post that you're keeping a constant aperture, and varying the shutter speed. You should keep your shutter speed at 2x frame rate (so at 60 fps, 1/125 of a second shutter) and vary your aperture. You always want to keep that 1/2x ratio, unless the situation calls for a specific slow-shutter or fast-shutter (think Gladiator's fight scenes) effect. Stopping up that Roki will only improve it, anyway.


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Ryan Holmes
Re: 6D + Rokinon 14mm + 720p = Super Grainy
on May 27, 2015 at 9:49:09 pm

[Tom Wille] "I'll ask you the same question, though, would you anticipate a sharper image if I'm shooting outside to close the aperture instead of upping the shutter speed?"

If you're trying to get a deep depth of field (meaning everything stays in focus), then yes, closing your aperture down will help this. Anytime you run a lens wide open (at the extreme end of it's aperture) you'll generally get a softer image than if you stop down a 1-2 stops. This is especially true when using cheaper lenses like Rokinon, Samyang, some Sigma, as well as cheap Canon glass. Higher end stills and video lens tend to do better with this, but there are physical limitations to any lenses ability to focus light onto the sensor.

I have the same lens we're discussing, Rokinon 14mm, and haven't noticed sharpness problems on it. But again I'm not shooting it wide open (it's a wide angle so I don't need shallow depth of field) and it's tied to a Canon Cinema body.

Additionally, if you're shooting video you need to start controlling light with ND filters, not by adjusting your shutter speed. The shutter speed is affecting the way motion is perceived by the camera. Keeping your shutter at 180 degrees (which is double whatever frame rate you're shooting at) is the best practice for shooting, unless you have a specific need or reason to deviate from that angle.

In order to control light ND filters are the way to go. You can get ones that fit on the end of a lens (not the 14mm due to the bulge of the glass). For something like the 14mm on a DSLR you'd need a matte box to be able to control light. And here again, is one of the reasons that a dedicated video camera is great because most have ND filters build into the camera for controlling exposure.

Looking at that video link you gave, nothing is "wrong" with your footage. It's a little over exposed as Blaise notes. But the "quality" of the footage looks like standard fair DSLR type footage (and I'm not trying to belittle that as bad, please don't read my comment that way). Dropping a little color correction and sharpening on it are the way to go.

I would encourage you to look again at the Cinema line as you grow as you can now pickup a used body for the same price you paid for your 6D brand new (C100 Mark I is $3K brand new).

Ryan Holmes
http://www.ryanholmes.me
@CutColorPost


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Tom Wille
Re: 6D + Rokinon 14mm + 720p = Super Grainy
on May 28, 2015 at 2:46:07 pm

Thank you both so much, I learned quite a bit from this thread.

I did mess around with filters on the grainy footage. There's only so much you can do, so obviously I'm still not happy about it, but I'm just making due for this project.

I'll be taking some test footage with the Rokinon 14mm in both 720p and 1080p in an upcoming shoot and keeping the shutter speed at 180 degrees and closing the aperture a couple stops to see if there is any significant improvements. I'll return with my highly scientific findings!


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