Low Light Gh1 Vs Dvx100a

SLoNiCK said:
gastrolit

The 5d2 has 21.1 Mp on 24x36=864mm2 sensor area. This means that 1080x1920 pixels take up 85mm2. The size of a 1/3" sensor is 4.8 x 6= 28.8 mm2

5Dm2 takes 36*20~=720 mm2 in 16:9, then reads every third line from sensor and downscales it to 1080p, AFAIK. So, effective square is 720/3=240 mm2. Comparative with ~200mm2 for GH1 in 16:9 mode.
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Ok, so after the readout of every third line the intermediate result will be an image
of 1080x5616 pixels. Then it is downsampled from 5616 to 1980.
Are you saying that this downsampling is done with pixel binning?
(If you just throw away all but 1980 pixels in the horizontal line without pixel binning the effective light gathering surface will be what I wrote before)

I haven't been able to find any info about this, but if you are right and data from each pixel in the horizontal row is used it's good news.
 
jenningsp said:
if you use the stock lens, it's gonna be worse in lowlight than the DVX - and by this i don't mean noise/grain wize. i mean just being able to see something. i'm sure a pitch black image is super clean and has very little noise
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You can't talk about dynamic range and then ignore noise. It's part of the whole equation (signal to noise ratio, usable dynamic range, etc). And the DVX is an SD camera so for a fair comparison you would have to scale the GH1 footage down to SD and then compare their noise performance.
 
gastrolit said:
The horrible thing is that we still live in camcorder stone age because the 5d2 could have used ALL PIXELS on the sensor to gather the light and then use pixel binning to output a 1080x1920 signal.
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Nope -- can't do it, because the 5D2 is a bayer-pattern sensor. Pixel-binning would result in a monochrome image.

You need three sensors to be able to do what you want with pixel binning.
 
Barry_Green

You can wire same color sensels via gap transistors. Nearly 13 additional transistors needed for 4x4 block of GRBG bayer sensor. Unlock transistors - and get unified charge for every color. BTW, it will give huge readout speed boost cause it's nescessary to read 3 charges vs. 16 in usual case. May be worth for high frame rate.
 
divide said:
I can't point you to an official source, but this as been discussed earlier on this board, the GH1 use Point resampling, not Bilinear/Bicubic. However, considering the max sensor resolution is 4352 (width) whereas the 5Dii is 5616, resampling to 1920 produce less artifacts. The evidence of this is that GH1 produce some artifacts when filming horizontal/vertical lines, but fewer than 5Dii.
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Ok, but I'm not completely convinced though. I still have a hunch that GH1 only reads 3840x2160 (x2.1 effective crop factor) of the sensor except when the lens is at full WA. In this case some of the sensor columns may not be read out. A second explanation could be the barrel distortion algorithm. Until someone makes the 'measuring tape test', we won't know for sure.

BUT all in all, I'm believe the GH1 DOES properly resample (pixelbin) properly.
 
From my experience- which for the record may not be the most extensive but is quite possibly the longest with the DVX100 series. (I had access to a pre-release camera, and then received the very first two DVX100(P) cameras on the West Coast- first shipment from Japan was during the dock workers strike in 2002. I got two of three through, while the rest of the U.S. supply sat in a shipping container in Long Beach for over 3-months.)

Besides the GH1 having loads more resolution, my unscientific observational finding is that the GH1 has much better dynamic range (guestimate of 1.5 - 2 stops better than a DVX) For comparison, this is better than at least one larger format sensor camera which costs 10-12x the price of the GH1.

The GH1 also has significantly better low-light performance! The noise floor of the GH1 is probably between 6db to 12db below the DVX100. 8-bit 4:2:0 files are a bit of a shame, it's easy to see that these images could have a larger amounts of manipulation in post. Thank goodness for the all-manual controls, so you can get there on set. It's a bummer for the DP to have to hit record for a moment, and then hit play to see the scene on a large monitor for lighting. Kind of reminds me of film back when video taps were an expensive "luxury" item.

I wish manufactures published fill factor on the box right next to megapixels. I don't know what the fill factor is of the GH1, but my guess is when comparing some other (much more expensive) "professional" cameras to the GH1, the GH1 is capturing such fine low-noise details by utilizing a modern sensor with a combination of oversampling, higher fill factor, larger well capacity, and extremely advanced noise reduction to get such a clean image.

I was looking at some GH1 1080p forward facing driving footage tonight on the big screen- stunning! I don't know a single pro who would have guessed the camera that shot those images cost under $2K!

You can easily achieve a codec fault with the GH1 if you're trying to break the image. However, I really feel now that if proper care is taken when setting up and executing shots (that is ----> shooting in a *professional* manner, rather than just "handycam-ing" it) you're NOT going to get obvious AVCHD codec faults. Yes, even in situations with multiple axis of motion. In two-three months from now there'll be significantly more footage posted, you don't have to take my word for it.


I.

Illya Friedman
Hot Rod Cameras
 
Illya Friedman said:
Besides the GH1 having loads more resolution, my unscientific observational finding is that the GH1 has much better dynamic range (guestimate of 1.5 - 2 stops better than a DVX) For comparison, this is better than at least one larger format sensor camera which costs 10-12x the price of the GH1.


Illya Friedman
Hot Rod Cameras
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Hunter has rated the GH1 (in video mode) to have 6 stops of usable dynamic range. 3 stops above 50IRE and 3 below.

the DVX has about 7-8 stops usable. 3 above 50IRE and 4-5 bellow with normal gamma. this is from my own testing.

though most people set the dvx to crush the blacks slightly by lowering the master ped. so you can expect a very similar image from both.
 
jenningsp said:
Hunter has rated the GH1 (in video mode) to have 6 stops of usable dynamic range. 3 stops above 50IRE and 3 below.

the DVX has about 7-8 stops usable. 3 above 50IRE and 4-5 bellow with normal gamma. this is from my own testing.

though most people set the dvx to crush the blacks slightly by lowering the master ped. so you can expect a very similar image from both.
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Yeah, but AFAIK Hunter didn't turn on iContrast which judging by the samples I've seen means a LOT. The sensor of the G1 can easily deliver 10 stops in RAW, so basically it's a question of telling the camera to use some of the bandwidth on the shadows.
 
jenningsp said:
iContrast doesn't effect the video mode at all. video mode is 6 stops and that's it.
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It depends, sensor DR isn't affected of course, and within normal bounds not even the JPG/MJPG DR is affected. But judging by the default setting samples I've seen (loads of crushed blacks), compared to the iContrast samples I've seen, it looks to me there is a different black point.

Crushing the blacks have various advantages, The noisy shadows don't show, Punchy 'consumer look', Blacks don't take up bandwidth, The frames less busy => needs less computing power => risk of compression braking up is lower.

The down side is the poor DR.
 
iContrast doesn't effect the video mode at all. video mode is 6 stops and that's it.
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Is this a fact from personal use? Read the info in the Panasonic global website before making statements like this or wait until you get a camera in your very own hands. There are multiple settings in the menus to control the cameras image that apply both to stills and movie. Just do more reasearch on that info.
 
I can't remember if Hunter tested dynamic range in 60P, if I remember correctly he tested at 1080. From the footage I've seen there may be more range in the 60P mode.
 
Kholi said:
You're absolutely incorrect. And it's a shame that you stated that as fact instead of just asking.
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i'm just taking hunters word man. i've been following hunters threads. i kinda gave up on yours after one thousand posts :) the crap to information ratio went through the roof

hunter richards said:
Greg Gory-

Hi! I chose iso 200 & iso 400 for the for the dynamic range test because I thought the base would be somewhere in there. Thats interesting that its at iso 100 though.

I did not test MJPEG.

I just tried the iContrast mode thing, it doesnt seem to affect the movie mode. Maybe it requires processing that doesn't happen realtime?
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from here - http://www.dvxuser.com/V6/showthread.php?t=169780&page=7
 
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You can ask Hunter if, since then, he's seen it work.

I have and I have examples of it. So, you're definitely incorrect.
 
Illya Friedman said:
The GH1 has more dynamic range than the DVX100. It's false and asinine to say otherwise.


I.

Illya Friedman
Hot Rod Cameras
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it's asinine to pass on information believed to be fact from a very reputable source?

the dvx has 7-8 usable stops and you can eek out a total of 11 from the sensor. it's not that bad. i guess it's a lost cause trying to convince people the DVX hasn't stopped being awesome just because HD was invented :)
 
jenningsp said:
the dvx has 7-8 usable stops and you can eek out a total of 11 from the sensor. it's not that bad. i guess it's a lost cause trying to convince people the DVX hasn't stopped being awesome just because HD was invented :)
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11? No way. I had 3 DVXs over the years and they are a noisy camera in cinegamma modes where you get the increased latitude. You could eek out 7 if you did not mind noise.
 
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