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View Full Version : How bad is the aliasing and the rolling shutter on the 7D?



iFilm7
03-07-2010, 06:31 PM
I'm actually considering the 7D over the HMC150, even after months of obssessing with the HMC, because of its interchangeable lenses and the price advantage.
but the cons are what is VERY unsatisfying for me.
how bad are they?

Barry_Green
03-07-2010, 07:49 PM
Are you asking how bad they are in relation to other cameras, or how much of an issue they are overall?

In terms of rolling shutter, the 7D is about par for today's crop of rolling shutter cameras. It's not any better or any worse than pretty much everything else. It can be an issue for some things, and a minimal issue for others; you have to set your own threshold for acceptability.

In terms of aliasing, the 7D/5D/t2i are all equal, and far worse than anything else on the market, because not only do they have luminance aliasing but also significant chroma aliasing that causes purple/orange patterns to show up in your footage. But, again, whether you'll ever have an issue or not depends on what you shoot. Aliasing and moire are worse when dealing with manmade things (bricks, chain link fences, picket fences, street lines, venetian blinds, etc) and fabrics with repeating patterns (tweed, plaid, corduroy's texture, lace), and thin-line detail (power lines, telephone lines, vinyl siding on a house).

With the moire/aliasing, it's really a case of "the more that's in focus, the more likely it is to bite you." So a deep-focus wide shot, yeah, you might get hit -- and the hit can range from mild to nasty. But a shallow-DOF shot, you're much less likely to get hit. Aliasing, by its very definition, only happens on whatever's in the sharpest focus.

There is no doubt the cameras are capable of stunning beautiful footage. And used properly, that is what you will get most of the time. Just be aware of the limitations and avoid scenarios or minimize the risk in scenarios where the aliasing can bite you, because you don't see it happening on the camera's monitor; you won't know until afterwards whether it even happened or not.

And when it happens, it happens sometimes but not all times. There's a tricky balance between the focused pattern and the relationship of how the resolved detail hits the sensor. Chris Santucci's simple comparison with the drapery really illustrates this well. You can have the fabric (or bricks or whatever else) in sharp focus and be fine at some distances, but if you change the distance, it might all of a sudden enter the zone where the aliasing gets incredibly noticeable.

Lgw90AYbaYM

In general, most folks are finding that the good outweighs the risk of the bad. And if you're shooting cinematic style with mild to shallow DOF, you'll eliminate a lot of the risk of moire ruining your shot. But if you're going into uncontrolled circumstances, the price you pay for $1699 shallow-DOF prettiness is that you might get hit with some moire that you may or may not find acceptable.

The bigger question you should ask is what type of shooting you're going to be doing, because there are some types of jobs (such as news/eng, long interviews, etc) where the HMC150 is unquestionably the better choice, because of all the things a video camera does that a still camera doesn't. I think the best usage for something like the 7D is as a replacement for something like a Bolex film camera, because the kinds of things we'd deal with in limitations with film (such as a 10-minute maximum recording time, no autofocus, etc) are the same kind of limitations the DSLR imposes.

iFilm7
03-07-2010, 08:28 PM
i would shoot close shallow dof, and far infinite dof, but as you said, it will hit me?
and i cant see the aliasing in camera? how come? but yeah, hope fully when i do full shots of streets that it wont hit me, and for the jello, will a higher shutter speed help? because im planning on using a pretty wide variety on shutter speeds.

ycabrera
03-07-2010, 08:41 PM
higher shutter speeds won't help. it might even make it worse. stick to 1/60 for indoor and 1/50 outdoor.

iFilm7
03-08-2010, 05:40 AM
PS as a little side question, 720/60p shutter can go up to 1/4000?? 1080/24p shutter can go up to how much?

andd oke. hopefully the aliasing isnt going to mess up my footage, and maybe there is something to work around it??

Barry_Green
03-08-2010, 06:58 AM
and i cant see the aliasing in camera? how come?
The LCD screen just doesn't show it.


but yeah, hope fully when i do full shots of streets that it wont hit me,
That is a vain hope. It will hit you then. That's exactly when it does strike.


and for the jello, will a higher shutter speed help?
Absolutely not. Shutter speed does not in any way diminish jello. The only things that help jello are:
1) have a steadier camera mount, and
2) use a faster frame rate.

iFilm7
03-08-2010, 03:49 PM
hmm.... wow, should i get the 7D? i dislike the aliasing it gives.... but the hmc150 doesnt really cut it for the selective focusing you know?
ugghhh ):
i think i should, its a hybrid camera as well so i could take nice pictures.
and its interchangeable lenses... i think ill get it...
although maybe you can suggest a camera that does pretty much the same thing as the canon 7d but without the aliasing... with a similar price...
but i highly doubt there is... -sigh- i guess im gonna have to be stuck with the lame aliasing.

Barry_Green
03-08-2010, 04:47 PM
Every DSLR has aliasing issues. The Canons have it worse because they do the purple/green chroma aliasing too; the others (Pentax, Nikon, Panasonic) don't do that.

If you're trying to decide between a video camera and a DSLR, look at the GH1 -- it's the most hybrid of them all, with the most videocamera-like features of any of the still-camera group.

iFilm7
03-08-2010, 07:41 PM
Every DSLR has aliasing issues. The Canons have it worse because they do the purple/green chroma aliasing too; the others (Pentax, Nikon, Panasonic) don't do that.

If you're trying to decide between a video camera and a DSLR, look at the GH1 -- it's the most hybrid of them all, with the most videocamera-like features of any of the still-camera group.

hmmm, the gh1 seems to be not as good with features as the canon, the 7D would be PERFECT for me if it wasnt for the aliasing issue..
like this http://vimeo.com/6487566
there is no aliasing as i can see and there were MANY deep DoF shots...?

yoclay
03-08-2010, 08:02 PM
Every DSLR has aliasing issues. The Canons have it worse because they do the purple/green chroma aliasing too; the others (Pentax, Nikon, Panasonic) don't do that.

If you're trying to decide between a video camera and a DSLR, look at the GH1 -- it's the most hybrid of them all, with the most videocamera-like features of any of the still-camera group.

It has been my experience that the purple/green chroma aliasing comes based more on the lens I use. In fact the multi-coating on more modern lenses is influencing this. It is certainly far more more present with my modern Canon lenses than with my older scallop style Minolta Rokkor 58mm for instance. Even my original C/Y Zeiss lenses perform better in this area than the Canon 24-105/f4 zoom for example. You can clearly see how the multi-coating on that lens is interacting with the sensor in creating the rainbow effect.

ROCKMORE
03-08-2010, 08:41 PM
Every DSLR has aliasing issues. The Canons have it worse because they do the purple/green chroma aliasing too; the others (Pentax, Nikon, Panasonic) don't do that.

If you're trying to decide between a video camera and a DSLR, look at the GH1 -- it's the most hybrid of them all, with the most videocamera-like features of any of the still-camera group.

I just took my new T2 out of the box and the new battery was on the charger, so I was looking around the room through the eyepiece with the camera off at the TV screen. Guess what, random live moire through the optical viewer all over the screen. Funny, had to laugh.

Osslund
03-09-2010, 05:28 AM
Just for fun I read the following article on what you have to know before shooting with a RED:
http://www.cinematography.com/index.php?showtopic=44340

After that I feel the Canons to be basically problem free ;)

MadHMC150
03-09-2010, 05:46 AM
Coatings or not, I had my hands on a 5D with an old 1.4 50mm lens and still saw heavy amounts of aliasing. Soon as the camera had my living room TV in frame, the speaker areas lit up like a christmas tree. Very distracting and looks so unprofessional IMO.

Pointed the GH1 at the same TV... still saw aliasing but much less and a faint grey color instead of purple/green. Although I wish it wasn't there its much more subtle.

iFilm7
03-09-2010, 04:09 PM
why i dotn like the GH1 is because the movie modes arent vast like the 7D
and that the 7d is the best hybrid cam for me if it werent for the aliasing... i think ill stick with the 7D even though the aliasing is there

Barry_Green
03-09-2010, 05:10 PM
why i dotn like the GH1 is because the movie modes arent vast like the 7D

Not sure what you mean here.

And if the 7D suits your purpose best, even with the aliasing, then yes, definitely stick with it.

Marco.L
03-10-2010, 02:44 PM
i just took my 7d and testing it , could not see too much aliasing that concerns me at all....

every camera has its cons...if u don't wanna anny con , shoot 16 or 35....

digital still has cons.....depends on you....


i'm loving my 7d loooks....specially at low lights conditions...

awesome with my 50mmF1.4 and 35mmF2....

i own a 7d and HVX with brevis35....pretend to make some mixtures with them to test it.... footage with interviews and etc....

still have no complains.....

thanks...

iFilm7
03-10-2010, 04:30 PM
i just took my 7d and testing it , could not see too much aliasing that concerns me at all....

every camera has its cons...if u don't wanna anny con , shoot 16 or 35....

digital still has cons.....depends on you....


i'm loving my 7d loooks....specially at low lights conditions...

awesome with my 50mmF1.4 and 35mmF2....

i own a 7d and HVX with brevis35....pretend to make some mixtures with them to test it.... footage with interviews and etc....

still have no complains.....

thanks...

haha then for sure i will stick with the 7D... over the HMC150.
and will the 28-135mm IS USM lens give very nice results?