7D aliasing - psychiatrist needed?

H

helcik

Member
Greetings to all 7D users.

I have recently bought a 7D and sofar did some hand-held test clips in my apartment. I am using 1080/25p, Neutral PS and sharpness down to the left.
Anyway, every single clip has aliasing on the edges which discourages me from further experimenting with 7D. I know I am looking specifically for aliasing issues but they are so much visible that every clip I shoot is a big dissapointment.
Lens which I use: C 50 1.8, S 17-70 at wide end.
Please guys, give me some workflow advises or just shoot me in the head so I stop staring on every edge in picture to see if it has aliasing...
 
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Really the best cures for it that I've been depending on are art direction and a teensy bit of soft focus. I downrez everything I do to 960x540 cause we deliver in SD here. I find that makes a bit of a difference if my focus is slightly off in the 1080 files.
 
Here's my advice: Start looking for aliasing (particularly moire) in the prime time shows that you see on TV. You'll be begin to see it everywhere. At that point, you'll realize that nobody in your audience (except for fellow pixel-peepers) really cares about aliasing, especially if it's not dramatic. You could also get other people to look at your footage and reassure you that it (sincerely) doesn't bother them.
 
There are some tricks you can do in post that I've seen online. Just do a search for alias fixes or different variants of "fix" "alias" "dslr" "rolling shutter" etc. There are a lot of video tutorials, one will might be somewhat helpful?
 
Everything that is in focus on a 7D* is going to alias. Period. If it's in focus, it will have aliasing. The more sharply in focus, the more aliasing it will have. This is an absolutely undeniable issue that is part and parcel of using a DSLR, because of the way a DSLR samples its image.

If you want to minimize the appearance of aliasing, you have to do three things:
1) never ever ever ever ever ever ever use the 720p mode of a Canon DSLR, and
2) use softer focus, and
3) don't move the camera

There is nothing else you can do.

However, you don't necessarily have to eliminate the aliasing; in fact aliasing is what gives the HDSLRs their "high def" appearance. But you can minimize much of the objectionable look of the aliasing. And frankly, that's what most of us are after.

Now, aliasing will be far more obvious on straight edges than it will be in natural items; you'll see the effects of aliasing much more obviously on a brick wall or vinyl siding of a house, than you will in a face. Aliasing is still happening in the face, of course (because if it's something that's in sharp focus on a DSLR it WILL be aliasing, it doesn't have a choice about it!) but the lack of straight edges or repeating patterns in a face makes the negative effects of aliasing far harder to see. And if you don't see it, it doesn't matter, right?

Also, aliasing really really reveals itself in motion. As you move the camera in one direction, aliasing moves in the opposite direction. So if you're doing a wide, deep-focus panning shot, it's gonna be aliasing hell. That's the nightmare scenario for a DSLR -- the wide-angle, deep-focus panning shot.

If you want to see how it's "done" properly, watch Philip Bloom's stuff. He knows how to avoid all the issues. Watch when he does a wide-angle deep-focus shot, the camera will be locked down -- no motion, so it's much harder to see the aliasing. And when he does a wide-angle moving shot, it'll be somewhat shallow focus -- if something's out of focus, it won't alias. And watch how many of his shots are super-shallow focus. Again, if it's out of focus, there's no aliasing.

Lastly, if you want the freedom of being able to move the camera, focus deeply, and have no aliasing, there is one thing you can do: get some Caprock anti-moire filters. But you need one for each focal length you plan on using.

If you have to shoot a deep-focus shot outdoors and don't have the caprocks, try using as absolutely deep an f-stop as you can possibly get. F/22 is a good start. Super-deep f-stops bring in an effect called "diffraction" which makes images defocused. F/22 isn't quite enough to get rid of all aliasing, but f/32 might be. At f/32, you'd probably have enough sharpness to get all the true resolved detail the camera can handle, but the diffraction would blur out all the aliasing contamination.

*or t2i/550d or GH1 or 5D Mark II or Nikon D3xxx or ANY DSLR
 
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I do notice it most with the TOkina 11-16, but on my other lenses it's not that bad. I really think the issue is completely overblown, like the rolling shutter. You just got to learn how to use the camera and know it's limitation and work accordingly. The longer the focal length, the less Aliasing.

For example, if I'm shooting a building with lots of lines with the Tokina, I usually just lock it down and soften the focus a bit. or just don't do fast movements.

Sometimes I get aliasing, but it doesn't kill me like a lot of other people. And it's true, you see it ALL THE TIME on T.V. It's not just the 7D that's for sure.

I think if you worry less about stuff like ALiasing and rolling shutter and just concentrate on shooting stuff and making cool projects, those short comings bother you a lot less
 
This is fabulous info Barry. As someone who's waiting to get a T2i, I REALLY appreciate this much detail.

Barry_Green said:
Everything that is in focus on a 7D* is going to alias. Period. If it's in focus, it will have aliasing. The more sharply in focus, the more aliasing it will have. This is an absolutely undeniable issue that is part and parcel of using a DSLR, because of the way a DSLR samples its image.

If you want to minimize the appearance of aliasing, you have to do three things:
1) never ever ever ever ever ever ever use the 720p mode of a Canon DSLR, and
2) use softer focus, and
3) don't move the camera

There is nothing else you can do.

However, you don't necessarily have to eliminate the aliasing; in fact aliasing is what gives the HDSLRs their "high def" appearance. But you can minimize much of the objectionable look of the aliasing. And frankly, that's what most of us are after.

Now, aliasing will be far more obvious on straight edges than it will be in natural items; you'll see the effects of aliasing much more obviously on a brick wall or vinyl siding of a house, than you will in a face. Aliasing is still happening in the face, of course (because if it's something that's in sharp focus on a DSLR it WILL be aliasing, it doesn't have a choice about it!) but the lack of straight edges or repeating patterns in a face makes the negative effects of aliasing far harder to see. And if you don't see it, it doesn't matter, right?

Also, aliasing really really reveals itself in motion. As you move the camera in one direction, aliasing moves in the opposite direction. So if you're doing a wide, deep-focus panning shot, it's gonna be aliasing hell. That's the nightmare scenario for a DSLR -- the wide-angle, deep-focus panning shot.

If you want to see how it's "done" properly, watch Philip Bloom's stuff. He knows how to avoid all the issues. Watch when he does a wide-angle deep-focus shot, the camera will be locked down -- no motion, so it's much harder to see the aliasing. And when he does a wide-angle moving shot, it'll be somewhat shallow focus -- if something's out of focus, it won't alias. And watch how many of his shots are super-shallow focus. Again, if it's out of focus, there's no aliasing.

Lastly, if you want the freedom of being able to move the camera, focus deeply, and have no aliasing, there is one thing you can do: get some Caprock anti-moire filters. But you need one for each focal length you plan on using.

If you have to shoot a deep-focus shot outdoors and don't have the caprocks, try using as absolutely deep an f-stop as you can possibly get. F/22 is a good start. Super-deep f-stops bring in an effect called "diffraction" which makes images defocused. F/22 isn't quite enough to get rid of all aliasing, but f/32 might be. At f/32, you'd probably have enough sharpness to get all the true resolved detail the camera can handle, but the diffraction would blur out all the aliasing contamination.

*or t2i/550d or GH1 or 5D Mark II or Nikon D3xxx or ANY DSLR
Click to expand...
 
gabrielflorit said:
This is fabulous info Barry. As someone who's waiting to get a T2i, I REALLY appreciate this much detail.
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There's more where that came from, I keep meaning to coalesce it all into a comprehensive article on how to get the best from these cameras while avoiding their downfalls. Some of the recommendations are going to surprise folks, some will absolutely fly in the face of conventional wisdom, but all are absolutely true and totally scientifically verified.

You can get amazing results from these cameras if you use them to their strengths. And you can get horrible results from them if you don't know how to avoid their problems.
 
Barry_Green said:
If you want to minimize the appearance of aliasing, you have to do three things:
1) never ever ever ever ever ever ever use the 720p mode of a Canon DSLR, and
2) use softer focus, and
3) don't move the camera

There is nothing else you can do.[/SIZE]
Click to expand...

Sorry Barry, but I've got to call BS on your remarks. Remembering when the EX-1 and EX-3 first came out, you were all over Sony with criticism and dissing. Well, it's now pretty widely accepted, despite your opinions, that the EX series exceeds the HVX cameras in image quality.

I find it interesting that you now use Phillip Bloom as an example of what to do right with a 7D, yet when he first started using the EX you found ways to criticize the results.

My advice is to never ever, ever, ever, ever, ever, ever tell a film maker to never ever, ever, ever, ever, ever, ever do this or that.

Come on - shoot soft focus, never move the camera and never shoot 720p?

I don't think so!
 
snp said:
Sorry Barry, but I've got to call BS on your remarks. Remembering when the EX-1 and EX-3 first came out, you were all over Sony with criticism and dissing. Well, it's now pretty widely accepted, despite your opinions, that the EX series exceeds the HVX cameras in image quality.

I find it interesting that you now use Phillip Bloom as an example of what to do right with a 7D, yet when he first started using the EX you found ways to criticize the results.

My advice is to never ever, ever, ever, ever, ever, ever tell a film maker to never ever, ever, ever, ever, ever, ever do this or that.

Come on - shoot soft focus, never move the camera and never shoot 720p?

I don't think so!
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Are you calling BS on his advice (which is pretty spot on for 7D shooters) or just BS on Barry... because, you didn't counterpoint anything he said.

720P shouldn't be used for wides, I think you can get away with it for mediums, etc. Shots where your plane of focus is on the foreground, not the background.
 
snp said:
Well, it's now pretty widely accepted, despite your opinions, that the EX series exceeds the HVX cameras in image quality.
Click to expand...

It's generally accepted that the EX looks sharper, not better overall.

I find it interesting that you now use Phillip Bloom as an example of what to do right with a 7D, yet when he first started using the EX you found ways to criticize the results.
Click to expand...

So?

My advice is to never ever, ever, ever, ever, ever, ever tell a film maker to never ever, ever, ever, ever, ever, ever do this or that.
Click to expand...

Like never use the on-camera mic for your primary audio capture? I'll turn your movie off in a heartbeat if you do that.

Come on - shoot soft focus, never move the camera and never shoot 720p?

I don't think so!
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Then your stuff will look like ****. Some people are okay with ****, so have at it.
 
snp said:
Sorry Barry, but I've got to call BS on your remarks.
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Really? Why not just try them out? My remarks are absolutely factual and based on extensive testing.

Remembering when the EX-1 and EX-3 first came out, you were all over Sony with criticism and dissing. Well, it's now pretty widely accepted, despite your opinions, that the EX series exceeds the HVX cameras in image quality.
Click to expand...
I was all over the CMOS sensor for the new issues that CMOS causes, and yes I had plenty of folks leaping down my throat about it. But you know what? Go back and look at my original CMOS article, now that all the hysteria has blown over, and look at what I actually wrote. I think you'll find that what I said is now no longer in dispute.

So much of this kerfuffle comes from people reading "into" what someone wrote, instead of reading what they actually wrote. Go back to the quote you gave of mine, and read the first line: IF YOU WANT TO MINIMIZE THE APPEARANCE OF ALIASING. Take it in context. The recommendations I gave were SOLELY about minimizing the appearance of aliasing.

Your response reads like I'm somehow condemning all use of SLRs for all circumstances -- which would be a total misread of everything I've said since day one of these products appearing on the market. So try judging the validity of my comments based on what I actually wrote, not on what you "think" I "meant" or whatever.

I find it interesting that you now use Phillip Bloom as an example of what to do right with a 7D, yet when he first started using the EX you found ways to criticize the results.
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When have I ever criticized Philip Bloom's shooting or his results? Ever? Bloom has mastered the art of shooting on a DSLR to make it look its very best, and he's worked very hard to develop that skillset. He's a model of how to do it right.

I seriously have no idea what you're talking about. I don't really think you do either. When I was on a panel with Bloom at SXSW, I opened a dialogue with him about hiring him to shoot my next film. Philip is a master shooter who has an absolute gift for composition and an eye for making incredibly attractive pictures regardless of the camera or the situation.

Come on - shoot soft focus, never move the camera and never shoot 720p?

I don't think so!
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Well, the thing is, it really doesn't matter what you or anyone else "thinks", all that matters is what actually happens. The OP was asking how to minimize or avoid aliasing, and I told him. And my advice is absolutely correct. And it was given for the SOLE circumstance of trying to minimize aliasing, and no other purpose.

Aliasing is incredibly worse in 720p vs. 1080p, so if you want to minimize aliasing, don't shoot 720p. Simple. Shoot 1080p and you will see much less aliasing.

Aliasing reveals itself in motion. If you don't want to see aliasing, don't move the camera. Simple.

Aliasing always reveals itself on the sharpest focus. If you want to minimize the appearance of aliasing, you have to defocus. That's just... obvious. How can you possibly argue with that? It's common practice; everyone knows that when moire shows up you defocus a little and it goes away.
 
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Imho

Imho

Barry_Green said:
For home/personal stuff, yes. For professional projects, no. I still have a GH1 but sold my 7D.
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Barry Green's opinions regarding Sony and Canon cameras seem to be clouded by his status as a Panasonic employee, contractor, supplier or supporter - which ever he is. Either way, to me he appears biased and I doubt his credibility when analyzing or criticizing other products. Phillip Bloom, Kholi, Papa, Mcgeedigital and others, I believe - I've seen their work.
 
^ who pissed in your coffee this morning? And who do you work for that makes you all bent out of shape about this.

Sony perhaps?
 
snp said:
Barry Green's opinions regarding Sony and Canon cameras seem to be clouded by his status as a Panasonic employee, contractor, supplier or supporter - which ever he is. Either way, to me he appears biased and I doubt his credibility when analyzing or criticizing other products. Phillip Bloom, Kholi, Papa, Mcgeedigital and others, I believe - I've seen their work.
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Hmmm, Ill keep this superficial as I dont know you, youre probably a nice fellow.

Did you read Barry's response to your first post. Sheesh, I think that alone should tell you something about Barry. He answered you politely and concisely even after you stuck it to him.

I havent always agreed with Barry, but the man comes with honesty thats a given. Your approach to this is inappropriate.
 
snp said:
Barry Green's opinions regarding Sony and Canon cameras seem to be clouded by his status as a Panasonic employee, contractor, supplier or supporter - which ever he is. Either way, to me he appears biased and I doubt his credibility when analyzing or criticizing other products. Phillip Bloom, Kholi, Papa, Mcgeedigital and others, I believe - I've seen their work.
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Excuse me, but WTF? Clearly, the only person who's biased here, whose mind is clouded, is you. Your statement is almost libelous.
 
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