shooting SD has horrible aliasing... 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 February 23rd, 2007, 03:37 AM   #1
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shooting SD has horrible aliasing...

I shoot freelance a lot, & some of the companies have gone the HDV route & some still insist on SD, & that's where my problem with the A1 is.

I've been experimenting in SD (4:3 & 16:9) while monitoring through the BNC out & noticed some horrible looking aliasing, more noticeable in wide to mid zoom range. It seemed so bad I thought I'd shoot a bit of the same scene, which is lit well & see if it's hopefully much better looking upon playback, even though I seriously had my doubts. I was right. It's terrible & just plain unacceptable. Fortunately I haven't had a gig that calls for SD yet.

I've read many more positive posts here regarding how good the A1 looks shot in SD than I've read negative posts, & all I can do is scratch my head & wonder if there's a problem with mine. I've tried many tweaks, presets, etc. to no avail. Anyone have a clue? Surely this isn't normal.

At this point I either have to keep my DV500 (which I'd really love to sell) for such jobs, or shoot in HDV and downconvert to hand over SD raw footage dupes.

Thoughts?

Bill
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Old February 23rd, 2007, 09:47 AM   #2
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Is the aliasing you're seeing only on the bnc out, or is it there on tape too? Really odd, as I've only used the A1 for sd so far, and haven't seen it at all. I'm shooting 24f with preset 18 which is actually a +1 on sharpness, and I'm still loving it. Any grabs or footage you can post?
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Old February 23rd, 2007, 09:50 AM   #3
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I've shot two different things in SD and see no problems at all. I use the CF1 setting, shooting 24f, and I took down the sharpness one notch, pressed the blacks a little and increased saturation just a bit. It could be you have the sharpness up too high?
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Old February 23rd, 2007, 11:10 AM   #4
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It sounds like possible monitor issue. Maybe it's related to scaling or monitor resolution. Did you try to connect your A1 to some other monitor or even regular TV? What if you connect other source of SD signal to your monitor. Does the same problem occur then?
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Old February 23rd, 2007, 01:47 PM   #5
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I'm having some issues with regard to DV and the A1 as well -- check out my thread:

http://dvinfo.net/conf/showthread.php?t=87363

In short, the DV capability of this camera does not seem good to me at this point. Lots of noise issues, and very flat, soft looking images. (that is, without custom adjustments)

For those who are saying that it is very good (and some say that it is exceptional), what are you comparing it to? In the above thread, I've compared the A1 DV to my XL1s DV -- with the XL1 being better.

Again and as I mentioned there -- perhaps I need to tweak, tweak, tweak...
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Old February 23rd, 2007, 01:57 PM   #6
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I'm comparing it to three+ years of shooting with the dvx100a. James, if you haven't experimented with the extensive controls and 18 presets from the library, then your conclusions are way too premature. The A1 comes out of the box flat, it's shipped with very neutral, bland settings, it needs to be customized to look the way you want.

After 100+ spots with the dvx, and only 4-5 under my belt with the A1 (in SD), one thing I can assure of is that this cam is less noisy than the dvx, and the image is pleasingly sharper.

Be patient, spend some time reading here, experiment, and if after that you have specific issues, re-post with some details on your settings & monitoring setup and whatever issues you're seeing.
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Old February 23rd, 2007, 02:05 PM   #7
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James -

Switching HD camera to SD mode will not improve low light performance. It still the same HD sensors that gather light and the same processor that scales images down to SD resolution.

I think some of noise issues you noticed are related to fact HD cams are not as light sensitive as SD. In-camera conversion is never as good as post-processing.

In my opinion, comparing to XL2, SD performance of XH A1 is just a little bit worse, but still more than acceptable. Well, that's with reference to the best SD DV camcorder, imo, but I agree with Stu's opinion regarding DVX100.

Built-in SD capability is certainly a good thing, but personally I'd prefer to always shoot HD and downconvert in post if necessary, packing much more color information than DV camcorder could ever produce. With Canon's HDV camcorders, conversion gets you pretty close to 4:4:4 SD.

That said, it is possible some units could suffer from different imperfections, also regarding BNC output.
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Old February 23rd, 2007, 02:30 PM   #8
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I'm with Bogdan on this one. I just shot a Greenscreen key with the HDV settings. I converted the 16:9 HDV into 4:3 SD using the DVCPro50 (4:2:2) codec and the results were great.

Of course, when I downcovert into DV using a Final cut timeline, I get mediocre (at best) results, but sometimes I have to do that for workflow purposes.
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Old February 23rd, 2007, 02:42 PM   #9
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Stu –

I get where you’re coming from. Having shot still and video for the last 15 years, I’m fairly confident of my observations. But I will agree that I need to spend more time with the custom settings, however -- my specific point is exactly this – this cameras DV performance, straight out of the box, as compared to the XL1 andXL2 is not as good – that is, without the aforementioned tweaks.

I suppose I like cameras that look punchy and dynamic straight away as opposed to having spend lots of time tweaking, etc.

Not trying to pee on anyone’s church here, heck – I own the camera now. But, based on many others posts in regard to how great the DV looks out of this camera (out of the box), I’d respectively have to disagree. Maybe once I tweak away, I’ll feel differently – and will absolutely report back then.

And perhaps this is asking too much, but after spending $3500 for the camera, it would be nice to have a present or two – factory ready that is, that punches up the image. Why not? Yes, I know I need to delve into it for myself, but having something to start off with would be a real benefit -- particularly insomuch as this camera is shipped very ‘flat’ – more so than any of their other cameras in my opinion.
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Old February 23rd, 2007, 03:09 PM   #10
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I'm was using a Sony PVM-1350 monitor & get the same results on playback, whether playing back through the A1 or a DSR-11 (composite or Y/C, no difference).

I just tried running it through a 32" LCD widescreen TV in 4:3 mode & nothing has changed. So, it's not a monitor issue, nor is it a BNC issue with the A1.

Sharpness settings were neutral. I've tried the default settings as well as the presets gathered from the forum.

I'll get to posting either screen shots or a short clip since movement really shows the garbage :-\ , however... I don't seem to have the priviledge of posting anything here as of yet. The posting rules at the bottom left still say "you may not post attachments". There was a thread not long ago I stumbled on where someone asked how to post a simple pic & Chris responded with something about there being a button under the text window, which I responded that on mine there's only "Submit Reply & Preview Post", nothing else. I didn't get a reply regarding that, so who knows. I suppose if nothing else I could use something like yousendit.com or something similar & just post the link.

Bill
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Old February 26th, 2007, 06:39 AM   #11
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James-

I share your opinion regarding the SD capabilities of the camera. Coming out of the box, they're not too convincing. After having read the other postings here, I assume that there could be differences in quality between individual units. The SD - shortcomings of the MY unit (and probably yours as well) are just too obvious to be overseen, even if one is a 'dedicated HDV filmmaker'. And - if many experienced guys here say, that the SD performance of THEIR XH's would be superb, I tend to believe them.

I gonna go a little bit deeper into that. Will bring my cam to CANON service today, because the ear jack is (definitely) faulty after just 5-6 days of normal ENG use. Will ask them to check the 'SD issue' as well and will let you know what they say.
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Old February 26th, 2007, 01:57 PM   #12
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I've been shooting 24F SD for a friend's documentary. He has an XL2 that we both have shot with, and he now wants to use my XH A1 all the time, saying its SD is looking better than that from the XL2. I haven't compared the two side-by-side, but I'm taking his word for it. I use the Cine1 setting, with black press and just a little color warming and saturation, as well as a little softening.
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Old February 26th, 2007, 06:35 PM   #13
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As soon as I get to more extensive testing with the A1 (plus a friend's A1 as well) & my other camera for comparison, I'll post something. I was almost at the point of getting a bit obsessive getting to the bottom of this & realized I wouldn't get much work done if I did. :-\

More to come. And thanks to all.

Bill
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Old March 5th, 2007, 03:56 AM   #14
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Hi Bill,

Did you solve your problem as far as aliasing is concerned ?
I noticed the same issue on mine (PAL XHA1) : big aliasing in SD mode (either 25F or 50i). Image wonderfully sharp but this aliasing in SD made me nervous. I found a way of reducing it by turning down the H/V balance in the presets to -9. It smoothed the image and the aliasing has almost deasapeared. I find it weird though to twick the balance to its minimum to have an acceptable image.

Did anyone else have a similar experience?

Pascal
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Old March 5th, 2007, 12:47 PM   #15
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Pascal, no I haven't. I've had no time really, but will get to it eventually.

I'll try the H/V balance suggestion, but the few companies that still want SD might scoff at any softness :-\

Thanks,
Bill
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