XH-A1 ... chromatic aberration reducer! at DVinfo.net

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Canon XH Series HDV Camcorders
Canon XH G1S / G1 (with SDI), Canon XH A1S / A1 (without SDI).


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Old March 10th, 2008, 09:12 PM   #1
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XH-A1 ... chromatic aberration reducer!

I've been playing with the Canon XH-A1 for some time and was rather distressed last year with the level of chromatic aberration that the camera showed out of the box. Adding the Brevis non-flip adapter didn't help.

With the development work going on with our flip module, we noticed something that was a bit hard to believe...namely that the camera seemed a lot cleaner with respect to chromatic aberration when the Brevis/flip combination was on the camera. Other users with the XH-A1 reported the same thing, so combined with some lens testing, we examined the bare camera vs. use with the Brevis/Flip and a Canon 50mm f1.4 lens.

At this point a few things are very apparent:

1. Using the 50mm lens at f5.6 and the XH-A1 at f4.8 gives about 100 more lines of vertical resolution as opposed to wide open apertures on both.

2. The XH-A1 is definitely cleaner with the Brevis Flip/CF1Le/50mm f1.4 lens than the bare camera is all alone.

A 91MB quicktime file is here (slower).

The flash version (faster) is here at the end of the page.
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Old March 30th, 2008, 03:32 PM   #2
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I compared screen grabs of an xh a1 and an HVX200. The XhA1 had very bad chromatic aberration in that grab. I hope this isn't a reason to avoid the cam.
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Old March 31st, 2008, 10:23 AM   #3
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I compared screen grabs of an xh a1 and an HVX200. The XhA1 had very bad chromatic aberration in that grab. I hope this isn't a reason to avoid the cam.
For me it was. ;)
I was renting the A1 all the time.
We made some docu shots with the HV20 and official shots with the A1.

When there was enough light, the HV20 has really beaten the A1 - some of the A1 shots were unuseable because of the CAs.
There wasn't any difference in sharpeness between the two, though...


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Old March 31st, 2008, 11:16 AM   #4
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The CA is at the wide end of the XH-A1. You can't get the wide angle of the XH-A1 with the HV20 because it doesn't have one. At the long end, the XH-A1 has far less. The "L" series lens has very good clarity, especially for a 20:1 zoom range. It's even better at the the larger aperture openings where it remains sharp, allowing preservation of detail and shallow depth of field in conjuction with the built-in ND filters. I'm going to assume you were screwing ND filters onto the HV20 for your outdoor work, because honestly, if you can't beat the image of the HV20, you've totally sucked with the XH-A1, which since you were renting it, would probably not be that surprising. There is a significant advantage in horizontal resolution for the A1, as well for the vertical but you have to manipulate the horz-vertical balance setting to get it. The A1 is tuned by default for a smoother field blending, anti aliased look.

I've been learning with the Sony EX1 as well, and would note that at 60i the A1 is closer to that cam than the HV20 to the A1, with what I think may be better grayscale tracking for the A1. The EX1 is in a different league when it comes to 24p however.

For me, even in strong light the A1 will easily trump the HV20 for grainless shadow and facial details, cleaner "pop" yet always organic. Spend enough time as I have with the HV10, HV20 and XH-A1, and you'll see the weaknesses of the single chip consumer cams, infinite depth of field, neon exaggerations and bayer artifacts. Never mind low light. And if you've managed all those, I'm going to assume you've shot everything on the tripod because it's ridiculously shaky handheld.

The problem the A1 presents to new users is the learning curve to extract the video which it is capable of, which is actually awesome.
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Old March 31st, 2008, 11:21 AM   #5
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Originally Posted by Dennis Schmitz View Post
When there was enough light, the HV20 has really beaten the A1 - some of the A1 shots were unuseable because of the CAs.
Dennis, the HV20 has less CA in this instance because it's a single chip design. Elimination of the prism block removes one of the indirect causes of CA. It's difficult for a high zoom ratio lens to get the focal points accurate enough at all focal lengths to hit the prism face for proper separation.

Couple a single chip camera with a fixed focal length lens and you have eliminated most of the CA gremlins.

If it's any consolation, I get some CA with my HD lens on the F350.

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Old March 31st, 2008, 12:38 PM   #6
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Couple a single chip camera with a fixed focal length lens and you have eliminated most of the CA gremlins.
It's a pity that even the HV20 is better than the XH A1 in this respect. Totally kills my desire to get a professional camcorder next time. Maybe that's why several digital cinema systems like the RED use single chip systems?

If the CA can be removed in software by simply scaling the color channels, why can't Canon not put such software in their 'high end' HD camcorders? I'm so disappointed in them! And they are the same company behind the HV20.

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If it's any consolation, I get some CA with my HD lens on the F350.
Even the HVX200 shows much less CA than the XH-A1 as far as I've seen.

The trick of not shooting with the iris wide open is counter-productive when you consider that low light performance is one reason why people go for high end camcorders. If the iris can't be left wide open, then we're wasting light!
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Old March 31st, 2008, 05:34 PM   #7
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The Panasonic appears to have a higher price tag, shorter zoom range on the lens. How many viewers will see the CA on normal video? You have to pick the right tool for the effect/look you are trying to achieve. Nothing is free.
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Old April 1st, 2008, 02:42 PM   #8
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The Panasonic appears to have a higher price tag, shorter zoom range on the lens. How many viewers will see the CA on normal video? You have to pick the right tool for the effect/look you are trying to achieve. Nothing is free.
It's easily watchable on DVD.
Even some white paper were turning magenta in the corners... in Full Wide of course. This doesn't occur with normal or tele

But this was back in january.
We've switched to EX1. No more problems (at least with CAs ;))

@Tom:
I know what you mean. But at least in this aspect (which is very important for me) the HV20 seems to be far superior...


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Old April 3rd, 2008, 01:34 PM   #9
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In my mind the XH-A1, given it's performance with the adapter, becomes a very desirable cam even with the EX1 on the market. Image performance is excellent, tape workflow works great for docu shoots, and the image presets are world class compared to other cams.

Factor in the low cost, light chassis, and proven tape workflow, and I'd very confident recommending it. If you are concerned about rolling shutter and CMOS, three CCD's like this cam, or the HVX200 make them better choice for vibration, or strobe-prone shoots. In fact, we took the XH-A1 and EX1 out on a helicopter shoot last week and the I think the nod goes to the XH-A1 in terms of the how the CCDs and OIS handled a rather harsh two-prop helicopter. I shoot and test with the HV20, XH-A1, EX1, and HPX500 so the opinion is based mostly on experience with these three, and what our customers are using.
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Old April 3rd, 2008, 02:11 PM   #10
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Originally Posted by Dennis Schmitz View Post
It's easily watchable on DVD.
Even some white paper were turning magenta in the corners... in Full Wide of course. This doesn't occur with normal or tele

But this was back in january.
We've switched to EX1. No more problems (at least with CAs ;))

@Tom:
I know what you mean. But at least in this aspect (which is very important for me) the HV20 seems to be far superior...


Dennis
All cameras have their own pro's and con's. CA often come with high resolution and sharpness. I haven't tried HV20, but my experience is that small cam's not at all can compete with larger ones. You may not see the CA in a HV20 due to worse overall sharpness.
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