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Panasonic LUMIX G / GF / GH / GX Series
4K and AVCHD on a Micro Four Thirds system camera with interchangeable lenses.


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Old November 26th, 2010, 10:29 PM   #1
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GH2 1:1 Crop Mode

Does anyone know more information about this; is it accurate?:

"... the GH2's secret weapon - 1:1 crop mode... 1:1 crop mode is a tap directly into the sensor, it takes a 1920x1080 window from the centre of the sensor so no scaling or image processing is required. It then takes this RAW sensor data and bypasses the usual image processor completely, sending it direct & uncompressed to the encoder chip. It's stored in AVCHD 24Mbit, 24p but unlike the GH1 this is a decent rock steady implementation of AVCHD - a bit like the AF100, with b-frames and just more advanced all round. It looks better than the GH1's hacked 44Mbit AVCHD."
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Old November 26th, 2010, 11:02 PM   #2
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That all sounds about right, except that I have no clue about this bit: "It then takes this RAW sensor data and bypasses the usual image processor completely, sending it direct & uncompressed to the encoder chip"

The sentence is true in that cropped-sesnor mode certainly bypasses the down-scaling processing of the full sensor when in normal mode, but he already said that in the preceeding sentence, so not sure about what additional he is saying here.

And the last sentence likely depends on the kind of footage being shot - locked-off vs. handheld wideangle, etc etc.

The cropped sensor does sound very cool, provided you have sharp enough lenses.
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Old November 27th, 2010, 12:47 AM   #3
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Wouldn't the 1:1 crop mode-sampling a smaller area of the sensor- would also effect depth of field and possibly light sensitivity as well?
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Old November 27th, 2010, 10:40 AM   #4
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I think the DOF may be close to 2/3" cameras.

I'm actually very excited about that mode and it's one of the reasons why I have a GH2 on pre-order and will sell my GH1 once I get it.

Here's another example although you'll have to download the RAW file quickly because Vimeo will destroy it any minute now and it will be the web streaming version that you'll be able to download.
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Old December 4th, 2010, 06:27 PM   #5
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I expect many have already seen this, but Michael Reichmann at Luminous Landscape has posted some interesting data on this feature.

Panasonic GH2 1:1 Mode Revealed
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Old December 6th, 2010, 08:15 AM   #6
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The DoF of the 1080p crop is equal to a 1/2" sensor.
The DoF of the 720p crop is equal to a 1/3" sensor.


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Old December 6th, 2010, 02:05 PM   #7
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At least I said I think.

I guess the wishful thinking got to me.
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Old December 8th, 2010, 09:02 AM   #8
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In the 1:1 (16:9) 1080 ETC mode, the "windowed" sensor diagonal is about 9mm.

In the 720 mode, it is about 6mm,

For comparison, a 1/3" chip is 5.5mm; a 1/2" chip is 8mm and a 2/3" chip is 11mm.
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Old December 8th, 2010, 12:33 PM   #9
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With the f1.7 14mm, this feature makes the GH2 an interesting B-camera that can give s-dof cut aways, wide scene setting shot and second camera view without a lens change or much fuss. Interesting.
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Old December 10th, 2010, 03:31 AM   #10
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Quote:
Originally Posted by Daniel von Euw View Post
The DoF of the 1080p crop is equal to a 1/2" sensor.
The DoF of the 720p crop is equal to a 1/3" sensor.


regards
Daniel
So if I'm shooting 720p, how is there any benefit to using this camera vs. my Canon XHA1, which has 1/3" CCD chips? I thought the point of DSLR's were that their censors were so much bigger, but unless I'm mistaken, the 1:1 Crop Mode bring me back to the size of a video camera.
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Old December 10th, 2010, 04:08 AM   #11
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In 1:1 crop mode the sensor is reduced to a "native" size of 1920x1080 or 1280x720, so the benefits are no pixel binning or line skipping, that usually, introduce some artefacts to the images being recorded.

Sure, you no longer have the same DOF as a bigger sensor has, but on the other side, smaller DOF could be useful for some type of works (i.e. run & gun shooting). Further, it come possible to mount 16mm cine, 2/3", 1/2" and many C lenses without vignetting.

Those features make GH2 (in terms of lens choise), the most flessible camera ever made.
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Old December 10th, 2010, 06:16 AM   #12
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If I wanted a deep DOF I'd just continue shooting on my XHA1. The appeal of the DSLR's is the shallow DOF, so I'm not understanding how this 1:1 crop does me much good if I lose the shallow DOF.
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Old December 10th, 2010, 07:27 AM   #13
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Patrick. I suggest you read the article from the OP again. With the press of a button, whatever lens is mounted turns into a telephoto FOV *without a lens change*. One of the negatives with using a DSLR and fast prime lenses for SDOF is the money spent on more lenses, hauling them around and the time spent changing lenses to change the field of view. So with ETC, a 14-28 1.7 lens on a GH2 becomes a 28-56mm and then in ETC becomes something like 55-100mm all with apparently excellent resolution and image quality that's as good as a buku dollar high quality telephoto lens. As an example, go price out an f1.7 100mm lens. That's how much money ETC saves you. Multiply that by how many telephoto lenses you don't have to buy. And remember, the more glass you add, the less light you get. With ETC, you are getting a glass-less telephoto. Here's another article on the topic with an A/B comparison of using ETC versus glass:
Panasonic GH2 1:1 Mode Revealed

With skill, your XH-A1 is capable of shallow depth of field and I suspect the same physics apply to the GH2 in ETC mode. But remember, it's all an illusion:
Depth of Field Myth

The GH2 will give you the SDOF you want. There's no law that says you have to use the feature. Buy more lenses and change out the lenses during your shoot. Or, buy one of the other DSLRs that don't have 1:1.
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Old December 10th, 2010, 04:22 PM   #14
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Les, I understand how to get a shallow dof with a video camera, but the appeal of the dslr's is that you don't have to zoom from a distance, rather you can get shallow dof from any focal length. The thing I'm wondering is if it's a good idea to only shoot in the 1:1 mode, or only for telephoto. From what I'm reading the 1:1 mode is good because it prevents artifacting from scaling. If that's the case it would seem to me you wouldn't want to shoot it without the ETC enabled, which would however bring your effective sensor size equal to that of a basic prosumer video camera. Is this correct?
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Old December 10th, 2010, 05:49 PM   #15
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I don't think you can look at it as always this and that. Nor should you say the DSLRs have artifacts therefore you should shoot 1:1. The GH2 is reportedly made great gains beyond the GH1 leader in the artifact avoidance category. I would expect you can shoot in normal mode lots. The Luminous Landscape and Bloom reviews reinforce the GH2 improves things quite a bit. If I had one, I'd decide what to do for each shot just like anything else....use ETC for what it's good for, normal mode for the rest (SDOF and normal DOF).
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