Fringing

[Christopher Neville]

Lately while editing some of my footage, I have noticed that it is showing some mild to very bad fringing. These are outdoor shots near waterfalls. Things like leaves on dark rocks. I understand that slight fringing isn’t uncommon, especially with high contrasts areas that fall near the outer edges of the frame, but I wasn’t sure if the amount I was seeing was normal. It seemed much worse than other examples of fringing I have seen posted. Also, I also wasn’t sure if and how much the Canon WD-H72 wide angle adapter may be compounding these effects.

Yesterday I took some photos of high contrast scenes with my A1 and WA. The results were very bad. I also tried some more tests with and without the WA on. The fringing was bad on both. The effect was only very slightly worse with the WA. I was using Panalook 2 preset. I got close took a photo, then back about 5 feet, zoomed in to fill the frame again and took another. (I had read that zooming all the way out increased the fringing effect). I don’t have those images to show unfortunately.

I have 2 grabs from the footage I’m editing right now (water 01 & 02) and a few images from the Botanical Garden we went to yesterday. I would like to know, is the fringing I’m seeing typical with such high contrast scenes and does the WA accentuate this effect? Any advice or thought would be helpful.

[Christopher Neville]

one more I forgot

[Marcel D. Van Someren]

If you're referring to the red or green outline along the edge of the objects, that's known as Chromatic aberration or CA for short.

The A1 does have some CA that is sometimes noticible at the wide angle end of the lens. I'm not sure, but adding a wide angle lens may also exagerate the problem. Also, shooting with the aperture wide open may also add to likelyhood of CA.

I did see a little towards the outer edge of the images.

The only thing I know to do is stop down on the fstop a bit and try not to shoot at the widest angle.

Have you tried usng a polarizing filter?

By the way, the A1 is not the only camera that suffers from CA.

[Christopher Neville]

I had really wondered if my examples were similar to what other people were getting or was mine worse. Like I said, mine looked much worse to me than the others I had seen so I was worried about my camera. If mine looks about the same as everyone else's, that is okay. I will do what I can to reduce the effect.

Also I did wonder if anyone else that used the WA noticed a big difference in the quality of the image. I really like the idea of leaving the WA on all the time. From my testing I could barley see any difference in the amount of fringing, or CA, with or without the WA.

I have used a polarizing filter from time to time, but not with the examples shown. That is something to test out though.

[Jay Bratcher]

Just an observation, and possibly related - those images are very soft around the edges. In fact, I think there is more distortion than there is fringing. I don't know much about the Canon converter, but I do know that if you have zoomed in some with a wide angle lens, you can get soft corners and increase fringing. I have a Raynox converter on an HV20, and it is unusable at full zoom, but acceptable at maybe 50% or so.

[Mark Fry]

What apperture were you working at? With such small detectors (1/3" is medium sized by video standards but pretty small in the grand scheme of things) diffraction effects can become noticeable at small appertures - typically f8 and above. I try to keep the apperture at or below f5.6, using the ND filters, and faster shutter speeds if necessary. I'm just editing some footage from a friend's Sony FX1, and that shows purple/green fringes on a few shots. It seems he was shooting on a sunny day without ND and 1/100th shutter. The apperture was about f11.

[Steve Phillipps]

Correct about the diffraction. I don't have a formula to hand but with a 1/3" sensor you'd probably find that the diffraction limit (ie when the image will start to soften) maybe even wider than f5.6! But I think 5.6 is a good place to stay. Colour fringing is Translateral Chromatic Abberation, and theoretically shouldn't be affected by aperture, although as some folks have pointed out it can be more visible at wider apertures because it's more diffuse and so covers more pixels.
CA is just a fact of life with HD lenses, even the £35,000 Canon HJ40 has it - quite badly in fact, I was shocked when I first used one.
Steve

[Florin Berechet]

I have the same problem with my XH-A1, purple or green stripes on vertical edges of objects. And all these at the wide end of lenses. I tried different apertures but the stripes are in the same place. I zoomed in and they dissapeared.
I wonder, what has to be done to have correct shots when filming landscapes at wide end of lenses? Because most of the time I have to use the wide end. I know, the pictures I attached aren't the most inspired landscape and a real one maybe won't show CA so obvioulsy because of irregular contours.
Damn, I am a Canon fan and they say that Canon has very good lenses, is this CA issue a thumb down when it's about to purchase a good quality HDV camcorder? I searched over the Internet and most problems with CA are about Canon. A friend of mine ( he is a photographer) told me that might be something wrong with my camcorder. For a moment I believed him but then I read this thread and cooled down myself for a while . But still I don't believe, Canon lenses suffer from this "desease"....?

[Christopher Neville]

The only way I have been able to try and cope with the problem is to not fully zoom out, and try to frame my shot so that nothing high contrast falls near the outer edges. Using different aperture sizes didn't seem to have any noticeable effect. Using the W/A doesn't seem to make it worse either, so I keep it on all the time. With the W/A, I don't fully zoom out, but still have a perspective like I did.

It's not a solution, just a way to try and cope. I'm open to other ideas with how to deal with it.

[Florin Berechet]

Yes, you are right. Seems that zooming out and CA are tight connected :(. I also noticed that XH-A1 produces great footage (vivid colors, good contrast) when I zoom in around half of focal length.
Somebody said a few posts that XH-A1 is not the only one that suffer from CA. I found a few links about a Sony EX1 with the same problem. For the moment I am just angry on the marketing text from XH-A1: Canon optics: Benefiting from a 32.5-650mm (35mm range) Canon L-series 20x optical zoom lens with Super Range Optical Image Stabilizer, the XH A1 inherits the highest optical standards. Fluorite lens elements, Ultra-low Dispersion (UD) glass and multi-coating virtually eliminate ghosting, flare and chromatic aberration.

[Pavel Sedlak]

Yes, Canon XH-A1 has big CA.

But on the real world the people don't look for CA, so usually it don't matter (CA is noticable only on same part of movies). From standart distance from TV it is all right.

Wide Adapter from Canon make CA more noticebly, try to get better WA.

[Christopher Neville]

Originally Posted by Pavel Sedlak

Yes, Canon XH-A1 has big CA.

But on the real world the people don't look for CA, so usually it don't matter (CA is noticable only on same part of movies). From standart distance from TV it is all right.

Wide Adapter from Canon make CA more noticebly, try to get better WA.

Many people seem to think that the Canon WA is a good quality WA. Since you don't agree, can you list a WA you think is a better quality?

[Ann Bens]

In wideangle zoom a little in, this will cut down the CA's.

[Arthur Abramov]

WE were just shooting our movie last Saturday with two A1s' the wide shots were kind of fringy on the edges but the close ups were high end.

[Ken Wozniak]

CA is okay for broadcast - at least for The Travel Channel. I've seen some very bad CA on shows like "No Reservations" and "Bizarre Foods". Always on wide angle shots.

I know "No Reservations" is shot with Sony cameras, so it's not just a Canon issue.

Going mild telephoto eliminates CA because we're using the "sweet spot" of the lens. In other words, stay away from the edges. Right? So, if this is true, in order to eliminate CA at wide angles, we'd need larger diameter lens elements, capable of going wider than we have the zoom range set at. And a tripod mount on the lens. And barrels full of cash.

In the switch from SD to HD, lens diameters on cameras have not really changed, and sensor blocks are still the same sizes. Which leads to this question:

Were the CA issues always there, but only now becoming visible thanks to the increased resolution of HD sensors - or - do we notice it more now because HD lenses need to resolve more lines?

Or could it simply be that the manufacturers all want super zooms for marketing purposes and are pushing the lenses too far at the wide end?