Moire & Insect Eyes ??

Hi George D.

I am interested in the answer to this. Currently I have no real experience of video and I am a stills macro photographer who shoots a lot of high magnification, greater than 1:1 macro shots, with the Canon MP-E 65mm, amongst other macro lenses. At the moment I have put off my projects to get some video footage for a while, but I will be attempting it soon.

Whilst I have no real video experience and I know my limitations, I think maybe there is one factor that the experienced videographers and filmmakers are perhaps not taking into account. If you are shooting at a reproduction ratio of greater than 1:1 on a DSLR sensor, especially in the 2-3:1 reproduction ratio zone at realistic apertures for depth of field, then diffraction softening is an issue. To get reasonable depth of field on a DSLR you have to use apertures well within the diffraction limited zone. This means that for stills photography I have to use lots of careful sharpening in post-processing to restore the micro-contrast lost to diffraction softening.

The relevance of this diffraction softening is that whilst a problem for high resolution stills, it could be an advantage for video as it will limit the resolution at the sensor i.e. doing a job similar to a much stronger low pass filter. However, this is just speculation as I have never tried it for video.

Also if I optimally sharpen an image for a larger web sized image of 1200-1400 pixels, and rely on the image hosting site's lower resolution images, you get noticeable moire effects on the eyes. However, if I re-size it myself with an image editor using bicubic, then you don't get this effect. Presumably the image hosting site uses a cruder downsampling algorithm than bicubic, and something similar probably causes this effect on video DSLRs.

Below is an example of this effect with a still image I have hosted on Flickr. The size posted was 1400 pixels and the lower resolution image is a Flickr resized one of 1024 pixels. It was taken at around 3:1 on a Canon MP-E 65mm using a 1.6x sensor DSLR at an indicated aperture of f11, but an effective aperture of nearly f45. The original out of camera image was much softer than this

1400 pixels

http://farm4.static.flickr.com/3303/4557130964_4eb848db9e_o.jpg

Flickr downsized to 1024 pixels

http://farm4.static.flickr.com/3303/4557130964_2a46911c7b_b.jpg
 
SteB said:
The relevance of this diffraction softening is that whilst a problem for high resolution stills, it could be an advantage for video as it will limit the resolution at the sensor i.e. doing a job similar to a much stronger low pass filter. However, this is just speculation as I have never tried it for video.
Click to expand...
Diffraction is a great help in DSLR video. When getting exterior deep-focus shots, the kind that are most prone to being contaminated with aliasing, I've found that going to f/22 helps clean it up a lot. There's still a significant amount, but it's greatly reduced. I think f/32 would probably get rid of just about all aliasing.

Note: this is relevant only for video. For stills, diffraction is a bad thing as it robs your image of resolved detail. For video, diffraction works as a low pass filter, eliminating spurious aliasing and only passing through an image that has about as much detail as the sensor can resolve anyway.

So while I haven't tested this for macro work, I think SteB is probably 100% right.
 
How do cinematographers get a workable DOF for unstaged outdoor macro shots with a large sensor video camera? Focus stacking won't work for unstaged movies so the only thing I can think of is using ultra wide lenses. Are there any ultra wide lenses with a high degree of magnification that can be mounted on a GH1?
 
noirist, this probably won't answer your question, and since i can't yet afford any new lenses right now, i find that a decent close-up filter (+3 or 4), allows the kit lense to get in really nice and close without losing a ton of detail. doesn't work well at full wide, but you can zoom all the way while being only a foot or so from what you're shooting and still be able to focus. it's a temp solution for me, and it's working pretty well.

EDIT: Bob Lorrimer on Vimeo utilises close up filters VERY well... here's a link http://www.vimeo.com/user943311
 
Chris Light said:
noirist, this probably won't answer your question, and since i can't yet afford any new lenses right now, i find that a decent close-up filter (+3 or 4), allows the kit lense to get in really nice and close without losing a ton of detail. doesn't work well at full wide, but you can zoom all the way while being only a foot or so from what you're shooting and still be able to focus. it's a temp solution for me, and it's working pretty well.

EDIT: Bob Lorrimer on Vimeo utilises close up filters VERY well... here's a link http://www.vimeo.com/user943311
Click to expand...

Thanks for the suggestion, but I don't think close-up filters will work b/c they only increase the focal length of the lens (and hence decrease the DOF).

But maybe extension tubes would work since they keep the focal length the same but increase magnification by decreasing the minium focus distance?
 
Canon 5D uses a CMOS chip that was designed for stills not film making so it has some problems that you might run into.

One Rolling Shutter Jello Effect. This company makes a plugin for After Effects. It might not fix all problems of rolling shutter with the Canon 5D but will fix most of them.

http://www.thefoundry.co.uk/pkg_overview.aspx?ui=47C4AB50-4636-4326...

I read about a caprock filter that fixes Aliasing and Moire problems here.

http://www.cinema5d.com/viewtopic.php?f=73&t=6489&st=0&...

Aliasing and Moire problems

caprock filter

http://caprockdev.com/antimoire.htm

Read all the comments on vimeo the filter is not 100% perfect about 95% there.

7D Caprock 2.0 Anti Moire Filter, Aliasing Filter

http://vimeo.com/7523222

If Aliasing and Moire ever become a problem then I would say pick up a Panasonic GH-1 and get a adapter so you can use Canon lens. Panasonic GH-1 does not have Aliasing and Moire problems. The Panasonic GH-1 does have Jello Effect Rolling Shutter issue, but all HD DSLR's have that issue.

You may want to look at
 
You must log in or register to reply here.
Back
Top