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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 September 27th, 2007, 02:22 PM   #1
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How to capture the best resolution from A1?

Hi All,

Here is my problem, I would like to know as how you guys maximize the best reolution when you film. I have done an interview ina room HDV 60i, used 500W light and NR2 medium.

After I captured the footage into Vegas7 and rendered it out and burned it to DVD the image quality was garbage and had blur.
Has anyone else came across the same issue?

Please share your knowledge and experiences in regards to this issue with me.


Thanks
Matthew
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Old September 27th, 2007, 02:54 PM   #2
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Do not use any NR (NR1 or NR2) if you can avoid it. With 500 watts of light for an interview in a room it usually should not be necessary NR can cause the images to look soft and/or have a trailing image sort of effect depedning on which type and how much you use.

Also, if you render HDV to standard DVD (not HD-DVD or Blu-Ray HD), the image will drop from HD to more like to SD resolution.
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Old September 27th, 2007, 05:34 PM   #3
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Matthew:

Good topic, but probably thousands of possible answers.

You should be shooting in 60i with a minimum shutter speed of 60. At a shutter speed of 60 or greater, I don't see how you would get motion blur in an interview.

How did the footage look directly out of the camera before rendering?

On the topic of resolution, I have been trying to make a simple table of:
Focal length-F/stop-subject distance-Est. DOF-apparent sharpness

Most of my testing has been done at longer focal lengths and subject distances. That Canon lens on the A1 just dosent behave like a DSLR lens is what I am slowly learning. Conventional wisdom said that at higher f stops, you will have larger DOF and better sharpness. But Im getting better sharpness at lower f stops. You should be shooting in manual (especially interviews) and maybe try lower f stops.

I am also seeing a lot of both barrel and pincushion lens distortions with the A1 lens. I live in a costal area and have a nearby bridge across the Cheasapeake Bay. When shooting the (totally level) bridge from the beach, it appears to be dipping in the middle. When filming out toward the horizon over the ocean, it appears you can see the curvature of the earth. Its not curvature, just severe barrel distortion. Granted, you would never see this in most situations, but for any architecture shots, you may have trouble.

One last gripe, I am having occasional, random instances of garbage footage being captured. It's a little hard to see that there is a problem on the camera screen, but on a HD monitor, it is muddy, ill focused appearing garbage. One time I noticed this happening, I tried to correct the focus manually to no avail. Stop & restart the capture, and it goes back to a beautiful capture. I would be curious if anyone else has experienced this.

Good luck
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Old September 27th, 2007, 08:27 PM   #4
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You can't just burn a DVD and expect optimum quality. You need to tweak the compression settings for data rate, etc. If the footage looked good when you edited before exporting to get it to SD for a DVD, then your problem is in your exporting and compression settings. However, using the NR2 does soften things a little, I've heard.

It's not a question of resolution. The resolution in HDV will be whatever the camera's resolution is. If your capture settings are not right, you can mess things up there, and if your timeline settings are different from your capture settings, it could render into something less desireable. And then, as mentioned, when you do your compression for DVD authoring, that's yet one more opportunity to reduce quality.

There should be no image blurring.
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Old September 28th, 2007, 07:47 AM   #5
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Quote:
...But Im getting better sharpness at lower f stops. ...
Makes sense. The sweet spot for most lenses is at a mid range F-stop. Smaller apertures may give more DOF but also introduce diffraction issues not present at larger apertures.

Lack of DOF is usually not much of an issue with 1/3" chips, more likely there is too much DOF for the shooters intent.
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Old September 28th, 2007, 08:47 AM   #6
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Originally Posted by Don Palomaki View Post
Makes sense. The sweet spot for most lenses is at a mid range F-stop. Smaller apertures may give more DOF but also introduce diffraction issues not present at larger apertures.

Lack of DOF is usually not much of an issue with 1/3" chips, more likely there is too much DOF for the shooters intent.
Don:

I agree that a mid-point is usually best. The A1 goes from F1.6 to 9.5 depending on focal length. So 5.6ish would be the mid point.

When I said lower F stops, I meant usually as low as you can go at that focal length, which is always below 5.6. Control exposure by increasing shutter speed and/or using the ND filter. Being a DSLR user too, this just goes against my DSLR experience using Canon DSLRs and "L" lens.

I will pull together some of my screen captures to show what I mean. If my experience with Canon DSLR lens is representative, Im betting there is also variation in the XH series lens between copies. And yes, I need to quit pixel peeping.
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Old September 28th, 2007, 10:37 AM   #7
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Generally the video lenses seem to be the best at mid ranges. However, when shooting interviews I generally try to shoot fairly wide open to reduce depth of field and pop the subject. I haven't noticed any softness problems, although your focus obviously has to be right on when shooting at a shallower depth of field.
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Old October 3rd, 2007, 02:32 AM   #8
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Does the video look good when previewing it in Vegas? By blur do you mean out of focus or a "jittery" feel? If it is not out of focus one thing to check are your settings for the mpeg2 rendering. As Bill said you need to really tweak the settings to get the best quality. Despite conventional thought I have even bumped the data rate at high as 9,200,000. I find when converting HDV to SD even high data rates (say in the 8,000,000 range) can still lead to artifacts. Another thing to try is playing with the GOP structure. Some older DVD players may have a hard time reading the files but the fewer compressed frames the better the video looks.

But, the first thing to check is to make sure you have the right field order. HDV uses Upper Field First (or Top Field First) while SD and DVD's use Lower Field First. All of the preset templates for Vegas 7 assume LFF so you have to go into the settings and change it to UFF or you will get a very choppy looking video that gives a blurry look.
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Old October 3rd, 2007, 01:01 PM   #9
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Quote:
Originally Posted by Jeff Kellam View Post
Matthew:

I am also seeing a lot of both barrel and pincushion lens distortions with the A1 lens. I live in a costal area and have a nearby bridge across the Cheasapeake Bay. When shooting the (totally level) bridge from the beach, it appears to be dipping in the middle. When filming out toward the horizon over the ocean, it appears you can see the curvature of the earth. Its not curvature, just severe barrel distortion. Granted, you would never see this in most situations, but for any architecture shots, you may have trouble.
If you don't have your zoom on the widest point, you won't have distortion. Its just like a wide lens, so zoom it in a little to get more of a 35-50mm "normal" look.
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Old October 3rd, 2007, 01:09 PM   #10
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Hi Guys

I did figure it out.
he actual footage was perfect crisp and sharp, however the Mpeg setting was was not correct.
At the end I got a master AVI out and burned the DVD in Ulead Movie Video Plus and footage was perfect the only problem that I have and need to be fixed is the motion blur.,which if you guys can help me with it I'll appreciate it.



Matthew
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Old October 4th, 2007, 08:55 PM   #11
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A1 quality

I have different issue with some noticeable grain;/noise in natural or low light settings. Just got camera and still learning. Any suggestions?
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Old October 6th, 2007, 02:54 AM   #12
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Quote:
Originally Posted by Jeff Kellam View Post

On the topic of resolution, I have been trying to make a simple table of:
Focal length-F/stop-subject distance-Est.

Conventional wisdom said that at higher f stops, you will have larger DOF and better sharpness. But Im getting better sharpness at lower f stops.

I am also seeing a lot of both barrel and pincushion lens distortions with the A1 lens.
The XH-A1 has the Canon "L" series lens (the "L" series is designated with a red stripe). I use Canon "L" series lenes (DSLR) and find the "L" series zoom lenses to be outstanding (as sharp as fixed-focal length lenses). I'm impressed with the XH-A1 "L" series lens.

About depth-of-field. My understanding is DoF is a mathematically-derived constant determined by aperture and focal length (not lens design). The rules of physics rule when it comes to DoF. If you find an authorative source that disagrees, please let me know.

About diffraction and small F-stops. The physics of light cause light rays to bend (diffract) when striking the edge of the diaphram. The smaller the diaphram, the greater the defraction. So while it is true that depth-of-field is greatest at very small apertures, at small F-stops you also get the image-softening effect of diffraction off the small aperture. Most lenses are sharpest at mid- F-stop.

About barrel and pincushion distortion. I didn't notice the distortion until reading your post. I immediately got out my XH-A1 and zoomed out (positioning a window frame at the top of the view finder). Yes, I see minor barrel distortion. That surprised me! When I zoomed in about 1/8 of the way (still very wide) the distortion disappeared completely. Finally, when I zoomed in about half way the minor pincushion distortion re-appeared. I feel this distortion is minor. I'd never would have noticed it unless I intentionally squared-off (perpendicular) with a straight-line object. And even then, I'd have to be looking for distortion to see it.

Thanks for making me aware of these minor lens distortions. Some day I may need shoot a subject where awareness of this lens distortion matters.
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