General T4i Aliasing questions because I must live with horizontal lines

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dogbrain

New member
I am the photographer, videographer, and webmaster for a model railroad club, and as such, I have to deal with many horizontal lines and miniature brick textured surfaces. I have read Barry Green’s article on aliasing.

The following 8 second clip on YouTube represents an example of some of the worst case situations I have to record. The brick structure center right and the locomotive louvers demonstrate aliasing issues: moire example

I am using a Canon T4i with the 18-135 IS STM lens and this clip was shot with these parameters,
Tv( Shutter Speed ) 1/125
Av( Aperture Value ) 6.3
ISO speed 1600
Image Size 1280x720
Frame Rate 59.94
Picture Style Faithful
Sharpness 0
Contrast 0
Saturation 0
Color tone 0

All of our videos to date are uploaded to YouTube.

I have read that manually focusing to create a slight blur rather than autofocusing is one suggestion. Since these videos, in many cases, are “set clips” which can be prearranged, I was thinking of buying this focus follower http://www.dslrsolutions.net/products/ to accurately preset multiple focus points for an appropriate blur.

There is one unanswered question about using this focus follower because I heard that the lens manual focus design is unable to identically repeat itself - does anyone have any experience with that issue for the Canon 18-135 IS STM lens?

I have Cyberlink’s PowerDirector 11 which I can use to post process clips to improve overall sharpness.

I was also thinking that tilting my tripod a small amount might create fewer “horizontal” lines.

Does anyone have any comments on these ideas or other suggestions for me to try?

Thanks,
George
 
Simply put...you are screwed with the canons. You cant really avoid it unless you get a mosaic filter (and I don't think they have it fot that camera). So i suggest selling that camera and either get a 5d3, gh2/gh3, or a 5d2+mosaic filter or 7d+mosaic filter. Used 5d's and 7d's are out there for reasonable prices.

I'm also curious as to why you are shooting with those settings. 720p modes in the first generation canons(i dont know about your camera being that its newer) are notoriously horrible when it comes to moire. Shoot in either 1080 30p mode or 1080 24p mode and it will be better. Also keep your shutter at 1/50 (or 1/60 depending on where you live) in 24p mode and 1/60 in 30p mode. Also you can add more light if you can so you dont have to go so high on your ISO.
 
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I would stay away from Mosaic filter as all it's going to do is soften and already soft image.....

First and foremost stay away from 720p 60fps unless you plan on doing slow motion. Second, turn your contrast and sharpness down, third NEVER and I mean NEVER shoot in Faithful , by far the worst profile due to the amount of moire that shows up in it, shoot in Neutral.

Finally if none of that works look to see if you can try some different lenses and run tests and more tests. Last note on this if you really want to avoid moire and aliasing the GH2 is your cheapest option with then more expensive Canon MarkIII and Cinema line.
 
If you check for examples of the mosaic filter in action, you'll find it does a very good job, and most users are able to increase in-camera sharpening as a result of aliasing almost disappearing. But +1 to moving away from 720p to 1080p..
 
I own a T3i and the only way to avoid moire, in normally unavoidable situations, is to use the 3x Crop mode which completely removes the moire. But i think they removed this option in the T4i.
 
They did remove it...which is too bad. That 3x crop mode is pretty nice at just 3x. Kind of like having an alias/moire free super 16mm ish sensor along with the native sensor size.
 
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