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Old May 27th, 2004, 11:10 AM   #1
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Optimizing XL-1 Image

Any suggestions on alternative lenses to the standard 16x to improve image quality? Is the Canon 14x manual the best choice or can I get something better for around $1,500? Also, will recording straight to a camera-mounted hard drive instead of tape greatly improve image quality?

Thanks for your time


Misha
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Old May 28th, 2004, 05:40 AM   #2
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NO OTHER recording method will improve your quality.
(s-video out with high quality cables to a very good capture board
might, but I even doubt that).

In my humble opinion you are looking in the wrong places for
quality enhancements. Better glass or another recording method
will not help you.

Is there better glass that might give you a better picture? Sure!
Will it be that noticable, no. Not for $1500. The best way to alter
the XL1 image is to get a mini35 adapter with cine lenses which
goes over $10K if you want to buy it. You could also rent, ofcourse.

Most people get a manual lens for the better handling and control.
In theory you can almost do the same with the standard lens.

What you should've done is tell about what image problems you
have and how you might get rid of it.

The absolute most important thing is know your camera. A lot of
people still do not shoot full manual. Most people have not even
touched the custom presets (black level can change a lot for
example) or shoot with custom set zebra levels etc.

After you thoroughly know your camera it might be best to invest
(and get to know this equipment as well!) in things like:

1) good quality monitor to see what you are recording

2) lighting gear

3) filters

4) audio gear

etc.

Audio gear you ask? Yes! This will help improve your image! Good
audio will enhance your image greatly where poor audio will
scream amateur.

But the most important thing of all is get a good story and some
good actors in my opinion. They will help mask a lot of other
issues.

When you have all that I would start worrying about lenses.
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Old May 28th, 2004, 08:55 AM   #3
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Thanks for your quick reply, Rob.

If your'e interested, Scott Billups has done some interesting tests using an XL-1 using auto/manual lenses, and recording on tape vs. direct to disk. The link is below.

It was after viewing this test that I asked my question about optimizing the Xl-1 image. Billups' got some impressive results.

Thanks again.

http://pixelmonger.com/graphicref194
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Old May 30th, 2004, 08:38 AM   #4
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Those pictures look interesting (I have his book), but they do not
tell anything.

Let me elaborate on this. In the world of DV there is NO difference
between miniDV tape and recording the signal that comes over the
FIREWIRE connection directly to a harddisk? Why? Because it is
the exact same signal. The camera (XL1s in this case) has a DV
chip which compresses the signal. This signal is the one that is
transmitted over the firewire port and layed down to tape.

Since it is a DIGITAL signal the tape basically has not impact on
the quality of the signal (ofcourse if the tape has been damaged
or used a lot the bits might not be recoverable and you will get
macro block compression errors and dropped frames which look
totally different from the pictures Scott has put up) and therefor
you cannot get those differences.

The problem with those test images is that they do NOT include
any explenation whatsoever. Looking at the big difference in
quality I'm assuming he was either recording to a different tape
system ((S)VHS) or he used a very high quality analog capture
board to capture from the S-Video out on the XL1S.

Whether or not that would yield more information is questionable.
I've not seen a test yet that used the S-Video out with a high
quality analog capture board and compared that to the DV/firewire
out. It might give a better result, but it might not either. That
totally depends on the quality of your cable, capture board and
the way the XL1S handles the S-Video out internally (which I don't
think anyone outside Canon really knows).

So basically the tests are worthless from my point of view. How can
we use those tests if we don't understand what is going on. My
feeling is that the images that where record on "tape" where
recorded on some other tape format than miniDV, but I might be
wrong in that regard, ofcourse.

I checked his site again and found how you came to this page.
The page that links to the test does not futher explain the difference
between tape and direct-to-disk. That's a shame. It does explain
that the last Canon SDI frame is coming from a homebuilt camera
with SDI out. Pretty impressive indeed.

So at the bottom line those tests still tell you nothing. It cannot
have been just miniDV tape and recording the signal over firewire
to a harddisk because that will not yield any picture difference
what so ever.

If you doubt my claims this is very easy to test for yourself. Setup
a good lit resolution chart or other high detail scene yourself
(indoors with your camera (close to a computer) on a tripod or
table). Hook the camera to your computer through the onboard
firewire connector. Start your NLE's capture part and start
capturing. Now hit record on the XL1S as well so it starts recording
to tape.

Record a 10 seconds or so and stop both recordings. Now capture
those 10 seconds from tape and import both streams into your
NLE and you'll see they are exactly the same. You could even take
a frame export from both streams, export in an UNCOMPRESSED
format like Windows bitmap (BMP). Load that up into a paint
program and substract the two pictures. You should get a
completely black picture in the end result (ie, the pictures are
identical).

Ofcourse you must line those two frames up perfectly which you
should be able to do if you have an NLE that can display the
streams timecode (like Vegas).
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Old May 31st, 2004, 08:28 AM   #5
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Yeah, what Rob said. :)


Actually, it's fantastic that this is the case because I captured an entire tape to disk because I had to ship the master tape off to a client in Europe and wanted a back up in case it got zapped by some x-ray machine or something but didn't want to leave 11 gigs sitting on my HD of footage I didn't need so I was able to capture it back to DV with absolutely no loss at all.


I looked at Bill's screenshots and it doesn't make any sense to me either. Depending on the camera and the computer there should be absolutely no difference in capture unless you are using a compressed codec to capture to disk, some substandard NLE to capture to or have a crapy computer or Firewire card.
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Old June 1st, 2004, 12:29 PM   #6
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Rob, thanks so much for your considered response. Your input is very helpful.
I'll try the test this week and let you know how it goes.
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Old June 2nd, 2004, 01:00 PM   #7
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For one thing, there's actually NOT much difference between those images. Look at them very closely. The only one that shows any significant improvement in sharpness is the very bottom one - and to me, it looks like that's just the only one that's focused correctly. The others all seem to be out of focus. The artifacts that I see really don't look like compression artifacts at all.

For instance, look at the first image on the list. One of the big defects in the image is along the left side. Notice how the black lines along the edges of the white triangles are slightly blurred. Compare it to the bottom image, where they're sharp and crips. This is NOT a compression artifact at all. It's a focus artifact, because it's consistent the entire length of the left side. If it were a compression artifact it would be blocky, and there would be a definite difference between the middle of one of those black lines and the corners where the black edge meets with the black triangles, but there's not. This behavior is the same across all of the images, except for the last one which is actually in proper focus.

I don't think the difference in focus has to do with the different lens, either (except that it might be easier to get a more perfect focus with a manual lens). Any of the lenses supplied with the XL1s (or designed for it) should be more than capable of focusing to at least the resolution of the camera itself, or they're useless - you would always get a fuzzy picture. Most likely, they're capable of focusing to several times better resolution, because that will give you a better picture.

The images in the picture appear to be more different than they are because they are all different brightnesses. But if you look closely you'll see that the artifacts are almost all the same - and brightness can be easily fixed in any decent editing suite. Or even the crappy editing suites.

If you want to get a better picture out of your XL1s you can try what some other folks around here are doing and disassemble the whole beast to get a raw signal directly off the CCDs and compress it yourself, but that's waaaaaaaaaaay too much work for me, and it's probably cheaper and definitely easier to just get a better camera.

Better yet, just follow Rob's advice and get better lights, audio, actors, and scripts.
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