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Old July 24th, 2004, 05:16 PM   #1021
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Hey Ben,

How much was that camera?

Also is the software easy to use to capture material, especially if you're just using RAM?
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Old July 24th, 2004, 05:17 PM   #1022
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Sorry Jason I have not seen the Viper stuff...

yes I have seen that 35mm image and it does look bad..but I can see how post can fix that ..bt SMEAR is not somthing you want to fight..its jsut BAD...Jason you know what I am talking about don't you? I seem to remember you pushed an image I sent you with black streaks in the darks?

post that if you can for everyone...that is a bad example because what I shot last night was so much worse that even the raw image had huge streaks in it!!

<<<-- Originally posted by Jason Rodriguez : BTW Obin,

Raw film doesn't look "good" either. If you're going to pack an image with a lot of dynamic range, you're not going to get saturation, and vice versa. Good saturation comes with increased contrast.

Take these images for instance:

http://www.24p.com/asc_web/35mm_girl.jpg

This is a 35mm frame with around 12-13 stops of dynamic range captured. You're not going to get "pretty" images when you do that. Her flesh tones are practically non-existant. Now increase the contrast, clip some of those whites, and you'll notice the saturation go up too. And then of course you can always punch the saturation also to get even better results.

But I think the RAW images we're getting right now are pretty good. Have you ever seen how "bad" the raw images from the Viper look? They are not pretty either. -->>>

All I have to do is point the camera at a window and expose for the inside room and the window will have huge black streaks that go across the dark area of the frame...the camera is at work ior I would shoot it now to show you guys
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Old July 24th, 2004, 05:22 PM   #1023
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does anyone know when a camera with the altasense chip is going to be available?
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Old July 24th, 2004, 05:24 PM   #1024
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Obin,
A question:
If you are looking at a gamma uncorrected image, how can you know how to expose to the interior light?
Aren't you overexposing?

Just a question...
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Old July 24th, 2004, 05:26 PM   #1025
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Wow, this thread has been busy! I'm on a business trip right now, and haven't have Internet access very much, so I apologize to anyone who has sent me e-mail.

Regarding the 10- vs. 12-bit issue. Yes, for some reason the 10-bit data from the SI-1300CL camera comes across padded into a 16-bit word like this:

0000xxxxxxxxxx00

where x = a real data bit.

I don't know why they do it that way, perhaps to make it easy to support 10- and 12-bit cameras with the same code.
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Old July 24th, 2004, 05:26 PM   #1026
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Okay,

Here's the "banding" picture

http://home.mindspring.com/~jrod/Banding.jpg

BTW, for this shot this is an extreme example, I guess with Obin it must have been much worse than this, because you would never CC an image to look like this!
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Old July 24th, 2004, 05:29 PM   #1027
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Ok, I see now :)

Is it always the same?
What is the supposed way to avoid it?
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Old July 24th, 2004, 05:30 PM   #1028
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Quote:
A question:
If you are looking at a gamma uncorrected image, how can you know how to expose to the interior light?
Aren't you overexposing?

Just a question...
Yes.

That has been my point with all these images since people started posting them. They're all overexposed! If you're seeing a bright image with a file that has no gamma correction but is suppose to be linear, then you're cramming everything into the top end of the dynamic range of the sensor. Don't be surprised when it doesn't take much to clip!

Has anybody been over to the uncompressed DVX100 page? That is a great example when you see the difference in brightness between the raw 12-bit signal and the 8-bit DV signal (that's been corrected). The 12-bit signal is much darker, so if you're trying to expose the 12-bit like the 8-bit, you're going to be disappointed in the dynamic range that you're getting.

Linear RAW images are not suppose to look good. They're suppose to hold information-just like a film negative.
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Old July 24th, 2004, 05:32 PM   #1029
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That is why I'm asking cause I think there is a little problem with the methods people are applying here.
Please try to be very carefull with the way you expose.

The RAW image should be really, really dark, to be able to get good results after correction.

With all the Sony DV cameras, you can see that with a very very bright spot, the CCD gives you a vertical white line so I guess this is a similar problem but CMOS style..
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Old July 24th, 2004, 05:37 PM   #1030
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Here's an example of a RAW linear file and the color-corrected version:

http://home.mindspring.com/~jrod/D60_RAW_1.jpg

http://home.mindspring.com/~jrod/D60_RAW_2.jpg

This is from a D60, and the image is blue because I forgot to do the white-balance correctly (you can fix that in Canon's software. BTW, it's also hand-held and I didn't stop down enough to get the edges in focus to keep the shutter high enough so that it wouldn't blur. Top of the Empire State looking towards the Hudson/Chelsea Hotel if anyone is interested). But I just use these two images to illustrate the point of what non-gamm-corrected linear images look like versus the "nice" counterparts we're used to seeing. You can't expose your camera like the second image because it will never look like that as a linear image. The tops of all those buildings would be clipped, and the shadows would look crushed. And you'd complain that it "doesn't look like film" :-)
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Old July 24th, 2004, 05:38 PM   #1031
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Good question Juan..this whole thing is hard because the "preview" we get is NOT what is in the raw file..so you must learn how to shoot with this chip...it's not even CLOSE to how you would shoot a DV or DVCPROHD camera..EVERYTHING must be DARK...if you have a hotspot that is close to 100% it will have the smear across the whole image

GREAT example Jason!!!! that is about how I have to shoot the 1300!!!

it's hard to shoot like that because you DON"T know what your really shooting!!!!
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Old July 24th, 2004, 05:40 PM   #1032
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Great example Jason!!
As a rule of thumb, when you are dealing with video (high bit depth like we have here) always expose for highlights.

Wow!! that image you posted gives me even great results when I correct it in 8 bit colorspace.I can't believe it.
My gamma was 2.2.
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Old July 24th, 2004, 05:48 PM   #1033
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Quote:
t's hard to shoot like that because you DON"T know what your really shooting!!!!
Yes, so the best thing is to either have a histogram showing you what's going on, make your software do the gamma correction for you on it's "preview" window (I'm not sure if the current software does this, Obin this may be something you want to talk to your coder friend about), or use a light meter an an optical viewfinder (paralax involved since we can't see through the lens with these cameras) to judge the scene you're shooting-just like film ;-)

Now Obin,

I don't remember seeing the streaking problems with your first footage that had a lot of hot clipped highlights in them.

Then I believe you switched lenses? And now you're getting streaks?

I'm still wondering if it's the lens and not the chip. CMOS chips are suppose to be much more tolerant of streaking/blow-outs than CCD's because of the way that CMOS doesn't have to do the whole "bucket brigade" thing.

Another thing I'm wondering is Ben can run his camera at 24fps and adjust the shutter from there to reduce or eliminate rolling shutter artifacts. How come you have to run the SI camera at 48fps and drop frames? Maybe if you could also run at 24fps and adjust the shutter from there you wouldn't have that problem.
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Old July 24th, 2004, 06:10 PM   #1034
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That's why I'm insisting that without quality lenses anything is posible, and to try to use at least SLR lenses.
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Old July 24th, 2004, 06:38 PM   #1035
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BTW,

One more gotcha!

I'm noticing that there's a definite amount of non-linearity in the shadows. Now this may be because I'm not really sure I've gotten a good RAW file before, but still, it seems as though the deepest shadows that come out when you convert your linear file with gamma correction shouldn't actually be showing-So in your conversions, you'd ideally want to adjust the shadow gamma back down, or apply a curves filter that adds a toe to the image. If you skip that step it seems to induce banding in the shadows.
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