It appears that almost all HD cameras/lenses exhibit some CA. High Definition magazine ran some tests on a range of broadcast quality HD lenses from Canon and Fujinon that cost between $30,000 and $60,000 and they all produced noticable amounts of CA. The magazine article concluded that the manufacturers are usure as to whether the CA is caused by the lens or the camera optical block or a combination of both. Ther is a frame grab from one of the above lenses here:

http://www.definitionmagazine.com/fringing/

Given that the H1 plus lens cost a mere fraction of any of the lenses tested in the above feature I really wouldn't get too hung up about it. Much of it is down to the fact that the H1 is the first low cost HD camcorder with the resolution to actually show up the CA. Take a close look at the Z1, HC1, HD100 or HVX200 and they all exhibit CA.

I've seen this too, but not so terribly obvious. I've had it happen to me at full-wide and telephoto with some CA, probably pumped up because I like to shoot Cinegamma 2 with +2 color gain.

I'm going to contact Canon about this. It's got to be rectified. Whether it's the lens or a problem with the prisms, it's got to be fixed.

I LOVE this camera, but it's something that's there and has to be addressed. I am going to post some shots I have where this is occurring. I'm also going to shoot more to see if it's a temporary or constant aberration.

Canon, there will be a storm of high-decibel complaints if this isn't addressed or acknowledged soon.

This should be approached in the same manner (expedient fix) that Canon employed with the old vertical lines issue in the original XL1.

You have to consider that if this is a permanent problem it limits your ability to control saturation...specifically to pump the colors. Your client may ask you to do this while monitoring, and be very unhappy with the results if given a scene with subjects that have very high contrasting edges.

I saw it in my trampoline SDI footage and it's problematic, for sure.

If it can't be fixed in a $50,000 lens it is unlikely that it can be fixed in a $4000 one. There are laws of physics that have to be dealt with here. In a couple of quickie experiments I found the CA to be less than a pixel at the edges of the frame. This is actually quite good. Images from this camera are not intended to be viewed close up enough that you can see the pixels. It's for movies and TV, not the cover of National Geographic.

Well, the effect I saw was pretty strong so it has me a little worried, but not monumentally.

Point taken, but I'm still concerned. What I've seen almost looked like a problem with the prism block, but I certainly can't say with even a whiff of expertise. The girls jumping on the trampoline have a bit of a "halo" of green and purple when you inspect it closely. I did shoot with a + 2 color gain and Cinegamma 2, so that might have contributed, plus I was fully wide.

Are we dealing with a serious problem or a mild CA issue?

Purple and green borders are killing me
 

I guess my big worry is I am shooting a feature on Thursday with this camera. I love the image we are getting but I want to know will this 'CA' destroy the saleabitiy of the project. I have posted some grabs from FCP . We had to shoot 50i to get it on to the computer for the moment but a KONA is coming. Barlow did your fringing happen in 24f as well.I can't get that onto my computer to look yet. I only have a 9 inch 400 lines monitor right now. HDlink card for 24 inch dell is still on the way. As we speak I am planning to get up and drive the 4 hours to selling company to do an eyeball test with their demo gear.


Images posted at:
http://homepage.mac.com/thefeature/FileSharing2.html

purple and green borders are killing me
 

Barlow I just looked at your slo mo trampoline again. Have a look at the trees on the right. That green fringe is what I am getting. Whoah that's bad. On the other hand the slow mo is great.

Hi David,

Oh yeah, it's there. I think I might have heightened it by adding a +2 color gain. I put up the CarlosDiego clip and it's ever so slight, but I think it's there too.

www.homepage.mac.com/mrbarlowelton

I think you're fine overall, but you might want to shoot flat for maximum latitude in post. Man, the CA would be the least of your concerns if the content's there. My low light footage has been phenomenal. You saw the "misc.Sundance2 clip", no CA. I have lit shots at slight tele that don't have the issue at all, and I bet a lot of your CU's will be max tele, if your going to use the 20x lens.

I think my advice would be to not push the color at full wide-angle. That's where I've seen the issue under specific circumstances.

It could be that the H1 is so damn sharp that it can't help but to have a little CA. I do know that it pixel shifts to achieve a full raster 1920x1080 SDI output...probably with the green pixels, so that might be contributing to the problem in some way.

David, I wouldn't worry so much. You'll get beautiful results, just watch for obvious contrasts (dark foregroud object, white background) and check for the anomaly. I doubt you're going to have any showstopping problems.

It just occured to me that everyone concerned over this issue ought to turn on the color bars, record them to tape and capture a frame. I've posted a frame at http://www.pbase.com/agamid/image/53638038 for those who want to see immediately what to expect. The point is that there are pixel (or more) wide transition zones between color bars. These clearly do not involve the lens as no lens is used but are rather artifacts related to the way in which color information is sampled and encoded. Could it be this that we are talking about in this thread?

CA in general, Post 'fixing'?
 

As has been touched on before, most lenses exhibit CA to some degree and with these 1/3" sensors the problem will be magnified greatly. If you think about how much a set of digiprimes go for *and* even they probably aren't high enough resolution to form an HD sized image at 1/3" sensor size.

Even on full frame or APS sized stills sensors you easily get CA, and that's with canon 'L' glass. (it's funny but in the stills world most people are obessive about whether a lens is 'good' or 'bad' and go through many replacements to find one they're happy with, i would imagine the same QA standards apply here too, maybe 2 replacements isn't enough)

In this particular case it's a question of whether it's too much, i appreciate everyone's comments and research as this helps me to work out whether i'll head down the HDV route or skip it.

But to add something constructive (i hope): on a lot of stills/raw processors there are options to help tweak the CA by scaling the RGB channels differently. Isn't there a workflow out there that could be used to help 'reduce' these effects on HDV?

I've always believe the bane of HDV to be optical glass. I really don't see an easy way out of this...

paul

A. J. deLange, I think what you are seeing there is simply the MPEG 4:2:0 compression of HDV. That has nothing to do with CA itself. But it may even enhance the effect.

What I am waiting for is till Canon offers the XL H1 body kit seperately. Then get a G35 (http://www.cinemek.com/) with the new relay lense they are working on and that should be available in a few months.

With this setup CA will be reduced almost totally I think if they make the relay lense right.

Jack

purple and green borders are killing me
 

Thanks Barlow. Today I bit the bullet and decided to concentrate on content over form.Such a hard balancing act at this end of the market. Thanks for your help.

Good luck David! Making a film is like going to war...at least you've got a very nice weapon at your disposal.

Please keep us posted, more than a few of us are very interested to learn of your experiences.

Barlow

Yes, there is a software package out there that one calibrates somehow (I've never used it) to obtain a set of coefficients descriptive of the CA of the lens. The software then radially scales the R, G and B images separately to reduce the lateral component of CA. To use this with video one would have to export the individual frames as JPEGs, do the processing and then put them back together as a movie. One would also have to calibrate for multiple focal lengths and perhaps focus distances.

The Green/Magenta fringing is indeed CA and can be accommodated in After Effects by scaling R&B channels - 99.6% is a good starting point

The Blue ghosting can not be fixed in post

I believe both are a symptom of the prism / CCD microlens interface and purchasing a body only option if it becomes available will help you none.

>The Green/Magenta fringing is indeed CA and can be accommodated
>in After Effects by scaling R&B channels - 99.6% is a good starting point

I don't think it's as simple as that though. This will only correct lateral CA however i suspect that there's also a lot of longitudinal CA which means the different wavelengths of light are focused at differing planes. Plus add to the mix the possibility of sensor alignment problems and whateverelse might be involved then the solution is more complex.

The best approach is to correct what you can (as you say) and then use post to reduce the visual colour effects of the other abberations. The green/luma channel is the master and the eye is pretty forgiving so long as it's not bright green/magenta/blue.

Maybe everyone does this already in post with these 1/3" cameras?

cheers
paul

The above will cure 80% of the CA as I have indicated


If you wish to clear out the rest which is mainly in the overscan area you will need to apply cosine-fourth scaling ( cosine raised to the power of 4 ).

Hi Everybody,

I just posted a VirtualDub filter which will allow you to do the independent R,G,B, scaling for Chromatic Aberration correction without having to do individual frame exporting, correcting still-image-by-still-image, etc., as described above. You can find it here.

http://www.dvinfo.net/conf/showthread.php?t=61274

Hope some of you find it useful.
Cheers,
Bill

Purples and Greens
 

Getting back to Michael's original concern, now once having more experience of the XL H1, I've started to suspect, that there's not necessarily something wrong with the camcorder Michael had. Instead, one does end up in certain situations with such an effect.

Before getting to this issue in more depth, I would like to add, that a similar kind of phenomena can be found with the XL2 as well. (I've viewed recently about hundred of hour of footages I took with the XL2 in about a year.) In fact, I've found also that my old Betacam SP tapes suffer occasionally for the same problem.

It seems that the critical issue is a sudden change from dark to bright colors, such as a shiny reflection of light next to something dark. In my case, whenever I've had a bright background sky and some dark object in the front, the border between the bright and dark is like a magneta or green line. However, in case of XL2 I can remember noticing something odd in the EVF while taking such shots, whereas in case of XL H1 the purples and green lines appear unexpectedly --and typically close to the corners of the image.

It seems one can avoid, at least in some cases, such artifacts by selecting a less steep gamma curve, setting the custom preset knee=low, and by carefully keeping the exposure low enough. If my experience is not misleading, it's better to keep the exposure rather low with HDV. For example, yesterday I shot trees having bright white load of snow in front of deep blue sky. If I tried to set the exposure to end up highlights with bright whites -zebra was set to 95, and the exposure was set just below that- then the purples and greens also appeared. But, setting the exposure lower removed the problem. This seems to suggest it better to shoot bit dark footages, and brighten them up in post.

In my experience HDV and the XL H1 seems to be quite a lot more challenging to use than DV cameras and the XL 1 or XL2. Especially, a "go and shoot" approach easily yields unpleasing results.

Help for chromatic aberration
 

Hi folks,
the chromatic aberration with the XL-H1 stock lens is certainly not tolerable for a camcorder like this, especially from a lens manufacturer like Canon. I have tested my own H1 with several EF 35mm lenses and there is not a bit of color fringing to discover. So even the old Canon SD 3x zoom 3.4-10.2mm has a lot less color fringing than the so praised new HD-20x lens.
But nevertheless since also the other 1/3 inch HD-cameras suffer from this lack, there is a little help by correcting the color shift in the postproduction. If you work with Final Cut Pro, there is a little plugin from River Rock Studios calles "Cheap Lens"

http://www.riverrockstudios.com/rive...cheapLens.html

As the name says the plugin for FCP normally is used to generate color fringing as an effect. The good thing is, that you can easily reverse the effect by a fingertip to eliminate nearly completely your chromatic aberration.
I treated a whole 60 minutes TV-documentary which was filmed with the Sony FX-1 so in the end there was no visible color fringing at all.
The only bad thing is the fact, that it consumes render time which normally should be used for more creative things.
But the only alternative would be to buy a HDCAM.

Hope it helps for most of you.

Regards
Roman Teufel
www.rtv-studio.de

My experience also seconds that there is less problems with the EF lenses than with the stock 20x lens. For some reason the camera still prompts the EF lenses are HD incompatible when the EF-adapter is in use. My EF-lenses generate images with higher contrast than the 20x lens, but besides that have not observed other issues. I'm not so sure about the 3x lens. I've taken some akward examples.

The problem may have to do also with wide angles, which tend to generate more small details into the image. Typically, as the EF-lenses are huge telescopes with the XL H1, and consequently, the images tend to have less small and tiny details.

Nevertheless, setting cine=1 or 2,knee=low, keeping brightest areas below IRE=90-95, and avoiding color saturation seems to remove somewhat the problem of magenta and green borders. The borders between dark and bright areas are where the difficulties seem to be generated.

Nice documentary
 

Roman: I viewed the trailer of your docu, To Where the World Began -- very nice! What did you shoot that with? And what's the music/who did it that's in the trailer? Very nice.