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Albert Smith

Black Magic Cinema Camera

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Wait for the MFT version and you can adopt about any lens on the planet (unless it is covering the sensor of course).

You can use 16mm glass, but have to crop out the vignetting from the 2.5k material, which leaves you with 1920x1080.

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Frank

This was a reply from Mitch Gross from Abel Cine and I just wondered what you think?

 

The camera does not offer that mode. The advantage of using a higher resolution (2.5K) to get 1920 is that you then do something called Oversampling (aka Supersampling), which reduces noise, increases relative MTF and all around improves the image. Most cameras which output 1920x1080 start with a sensor that is a higher resolution -- you just never see it. Additionally, Bayer patterning CFA on the sensor means that the functional resolution is only around 70% of a given numerical pixel count. So more res. is needed to get back to the image you really want. It's a good thing.

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Hi,

 

today I shot a quick (and dirty) test with a full set of 9 Arri Ultra16 lenses and a Red Scarlet @ 3K.

The active sensor size of the Scarlet @ 3K is almost the same as the one of the BMCC.

The Red @ 3K is using 16.65 X 9.36mm of the sensor, the BMCC 15.81 X 8.88mm. This is roughly a difference of 5% in size.

 

Then I upscaled the stills from the Red by 5% in Photoshop to see how much vignetting would be visible. I´ll attach the results.

From the 18mm on vignetting is clearly visible. The whole set would be usable by cropping 12-14% which means you would end up with 2.2K - 2.15K of resolution in RAW-Mode.

 

That´s all for today, what do you think?

 

 

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The whole set would be usable by cropping 12-14% which means you would end up with 2.2K - 2.15K of resolution in RAW-Mode.

 

That´s all for today, what do you think?

 

The question is how 2.2K with a Zeiss Ultra 16 compares with whatever else you could use at 2.5K. But since there are not a lot of fast 6mm lenses out there, it might be not much of a contest.

 

On the other hand, you could just shoot 2.4/1 and the vingetteing will just about disappear.

 

Cheers.

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The question is how 2.2K with a Zeiss Ultra 16 compares with whatever else you could use at 2.5K. But since there are not a lot of fast 6mm lenses out there, it might be not much of a contest.

 

On the other hand, you could just shoot 2.4/1 and the vingetteing will just about disappear.

 

Cheers.

 

Once I get my hands on a BMCC I´ll make comparative tests. I´m interested in the Ultra16´s because those are excellent lenses with a really fast aperture and useable wide open.

 

I don´t know why but I can´t upload any more pictures. Once I can upload again I´ll post the pictures of the missing 6 lenses.

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........I don´t know why but I can´t upload any more pictures. Once I can upload again I´ll post the pictures of the missing 6 lenses.

 

 

There's a limit on total upload volume. You have to delete some of the old ones. If you go into your account through your name at top right of page then go into "my settings" then "manage my attachments"

 

Edit: spelling

Edited by Gregg MacPherson

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Frank

This was a reply from Mitch Gross from Abel Cine and I just wondered what you think?

 

The camera does not offer that mode. The advantage of using a higher resolution (2.5K) to get 1920 is that you then do something called Oversampling (aka Supersampling), which reduces noise, increases relative MTF and all around improves the image. Most cameras which output 1920x1080 start with a sensor that is a higher resolution -- you just never see it. Additionally, Bayer patterning CFA on the sensor means that the functional resolution is only around 70% of a given numerical pixel count. So more res. is needed to get back to the image you really want. It's a good thing.

 

So basicly I'm being told two different things here.

 

1) You can crop into the BMC frame as it's 2.5k

2) You can't crop into the BMC frame without losing resolution as it has to be debayered from 2.5K to 1920x1080.

 

What I think this probably means is that you should debayer to 1920 but if you dont it wont make much noticeable difference unless you look closely at charts. Would be nice to hear a defintive answer using super 16mm lenses on the BMC then cropping to super 16mm frame size is going to do to your final 1920x1080 frame on the BMC. IE Resolution loss on a sensor that gives 800 lines will lose 100 or 50 or 20 lines of its potential. Maybe artifacts introduced?

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There's a limit on total upload volume. You have to delete some of the old ones. If you go into your account through your name at top right of page then go into "my settings" then "manage my attachments"

 

Edit: spelling

 

Thanks Greg, got it!

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So basicly I'm being told two different things here.

 

1) You can crop into the BMC frame as it's 2.5k

2) You can't crop into the BMC frame without losing resolution as it has to be debayered from 2.5K to 1920x1080.

In this case, you de-Bayer from 2.5K as that is what is recorded, then crop to 2.2K.

 

The reslolution at 2.2K will not be quite as good as from 2.5K, but not by much.

 

Here, my guess is that the quality of the lens will likely make up for the slight loss in sample size.

 

Cheers.

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Hi Noel

 

I know you will change the resolution by cropping to 2.2 K but you are missing the point. Read what Mitch Gross has said below

 

QUOTE

You have to debayer the 2.5K to 1920x1080 in order to retain 1920x 1080 resolution according to Mitch Gross who said

.The camera does not offer that mode. The advantage of using a higher resolution (2.5K) to get 1920 is that you then do something called Oversampling (aka Supersampling), which reduces noise, increases relative MTF and all around improves the image. Most cameras which output 1920x1080 start with a sensor that is a higher resolution -- you just never see it. Additionally, Bayer patterning CFA on the sensor means that the functional resolution is only around 70% of a given numerical pixel count. So more res. is needed to get back to the image you really want. It's a good thing.

 

Now read what Frank Glencairn said

 

QUOTE

Wait for the MFT version and you can adopt about any lens on the planet (unless it is covering the sensor of course).

You can use 16mm glass, but have to crop out the vignetting from the 2.5k material, which leaves you with 1920x1080.

 

 

Now I don't want to end up with mushy looking footage because I didnt downsample from 2.5K and instead cropped it as per Mitch Gross. So who is right or as I suspect are both right?

 

What I NEED to know is if cropping for super 16mm is going to lose me resolution or detail or leave artifacts and if so how MUCH resolution, detail will I lose from the 1920x1080 final image for editing and colour correction..

.

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What I NEED to know is if cropping for super 16mm is going to lose me resolution or detail or leave artifacts and if so how MUCH resolution, detail will I lose from the 1920x1080 final image for editing and colour correction...

 

You can rather easily see for yourself what happens when you crop.

 

Start with a BMCC RAW image (lots of .dng samples on the net).

 

Open with Photoshop, After Effects, Lightroom, Resolve or other program which can de-Bayer the image.

 

For 2.2K, resize the image (in Photoshop "Image Size" and check "Resample Image") by a factor of 109% (2400/2200).

 

For 1920x1080, resize by a factor of 125% (2400/1980).

 

What you see is exactly what you will get when you "crop". If you see a major difference between 2.2K and 2.5K you're eyes are much better than mine.

 

Cheers.

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There is a difference of opinion with many experts saying you will lose resolution from 1080p by cropping the BMC image that needs to be converted to 1080p before applying any cropping.

 

We need clarification of what is lost on cropping which may or may not be negligable before I would be willing to buy a BMC for use with super 16mm lenses.

So my post is VERY Important for those going in this direction to know.

 

Hi Noel

 

I know you will change the resolution by cropping to 2.2 K but you are missing the point. Read what Mitch Gross has said below

 

QUOTE

You have to debayer the 2.5K to 1920x1080 in order to retain 1920x 1080 resolution according to Mitch Gross who said

.The camera does not offer that mode. The advantage of using a higher resolution (2.5K) to get 1920 is that you then do something called Oversampling (aka Supersampling), which reduces noise, increases relative MTF and all around improves the image. Most cameras which output 1920x1080 start with a sensor that is a higher resolution -- you just never see it. Additionally, Bayer patterning CFA on the sensor means that the functional resolution is only around 70% of a given numerical pixel count. So more res. is needed to get back to the image you really want. It's a good thing.

 

Now read what Frank Glencairn said

 

QUOTE

Wait for the MFT version and you can adopt about any lens on the planet (unless it is covering the sensor of course).

You can use 16mm glass, but have to crop out the vignetting from the 2.5k material, which leaves you with 1920x1080.

 

 

Now I don't want to end up with mushy looking footage because I didnt downsample from 2.5K and instead cropped it as per Mitch Gross. So who is right or as I suspect are both right?

 

What I NEED to know is if cropping for super 16mm is going to lose me resolution or detail or leave artifacts and if so how MUCH resolution, detail will I lose from the 1920x1080 final image for editing and colour correction..

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Different "Super 16 lenses" cover different areas. For instance, the wonderful Illumina lenses cover the Black Magic Sensor from 16mm length upward (16mm, 25mm & 50mm). The 8mm, 9.5mm and 12mm all vignette. But 16mm and up is still very useful and there is a significant cost savings. With those lenses you can always pick up an Arri SR for next to nothing and have fun with film; shoot an episode of Walking Dead maybe...

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Hi will

Yes the 16mm and 25mm will be fine I'd prefer though to crop in to what would be a super 16mm frame size as that was what the lenses were designed for and will work best that way. I've got an Arri BL Sooo. No already shot film with it and although I prefer the look its just to expensive and time consuming.

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There is a difference of opinion with many experts saying you will lose resolution from 1080p by cropping the BMC image that needs to be converted to 1080p before applying any cropping.

 

What I NEED to know is if cropping for super 16mm is going to lose me resolution or detail or leave artifacts and if so how MUCH resolution, detail will I lose from the 1920x1080 final image for editing and colour correction..

 

Mark, your quote from Mitch Gross says there is no option in-camera to do the crop. He's referring to the compressed HD option. If you shoot raw you have the full 2.5K image and you have full control over that image. Unless you crop it to something smaller than 1080 you aren't losing resolution and won't lose image quality. What you might lose is the benefit of supersampling, but as another poster noted the difference probably won't be noticeable at these resolutions.

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Mark, your quote from Mitch Gross says there is no option in-camera to do the crop. He's referring to the compressed HD option. If you shoot raw you have the full 2.5K image and you have full control over that image. Unless you crop it to something smaller than 1080 you aren't losing resolution and won't lose image quality. What you might lose is the benefit of supersampling, but as another poster noted the difference probably won't be noticeable at these resolutions.

He went on to say

http://blog.abelcine.com/2013/01/04/why-you-cant-use-super-16-lenses-with-the-blackmagic-camera/

 

I understand the attraction, but I like to deal in practical ramifications.

Shooting the camera in 1920x1080 would not be "full HD." It is a Bayer-pattern sensor camera, which means that it must compute out the final full color image from less information. This means that the camera will be lower resolution than a traditional 3-chip prism 1080p camera by about 1/3. That's math.

The second issue is that you really will not know your precise frame. You seem to feel that this is not a major consideration but I would contend that it could prove quite an annoyance in actual use of the camera.

You can try to shoot in this manner. I wish you the best but I fear that you will find it a frustrating experience.

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You can try to shoot in this manner. I wish you the best but I fear that you will find it a frustrating experience.

 

I have no interest in shooting in compressed 1080 mode (although the image does look good from the tests I've done). The main attraction of this camera is its raw capability. I wouldn't sacrifice raw capability unless a workflow demanded ProRes right out of the box, and if had to shoot 1080 I definitely wouldn't use a lens that vignettes.

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Mike I think your missing the point

 

What he seems to be saying is that BMC Raw 2.5k translates down to 1920x1080 resolution when you debayer it down. NOW I'm not sure how that works but I guess that you have an option when you have the RAW file to process it down to full resolution 1920x1080p If you keep it at 2.5K Then you have a bloated 2.5K file that is not full 2.5K resolution. Therefore by cropping into this file image its similar or worse than just cropping the debayerd 1920x1080p image.

 

In the absence of anyone who knows the truth I can only GUESS there is a loss by cropping the 2.5K image. SO on that basis I know in order to get a super 16mm frame size on my GH2 I need set my frame size in AE at 720p or scale into the frame 33%. As the BMC sits in the middle of the two frame size wise My guess is you would have about 900p or scale into the 1080P frame 13%.

 

So quality loss will be about 13% of 1920x1080 to get a super 16mm framing. Then you would need to mask your monitor so you can frame when filming.

 

I guess though the quality loss will be minimal and it is going to be doable with a slightly soft image at the end of it.

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It works the same as most bayer sensor cinema cameras, you're oversampling so that when you debayer you can have the either an HD or I'd assume 2k image with good resolution. Cropping you'll be using a 2k sensor, with lower resolution. It's what the Alexa and RED cameras do.

Edited by Brian Drysdale

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What he seems to be saying is that BMC Raw 2.5k translates down to 1920x1080 resolution when you debayer it down.

 

2.5K RAW is first de-Bayered to 2.5k RGB. Different de-Bayer algorighms, working color spaces and bit depths yield different results (e.g., Resolve is not the same as Photoshop). In any event, the resulting resolution is something less than 2.5K.

 

After it is de-Bayered, the image can be cropped, downsampled or upsampled to any format (again with various algorithms, some better than others). Generally, downsampling increases the apparent resolution of the image, but the exact amount depends upon many factors.

 

I guess though the quality loss will be minimal and it is going to be doable with a slightly soft image at the end of it.

 

"Skyfall" was shot at 2.8K RAW, deBayered, and both upsampled to 4K and downsampled to 2K for theatrical distribution. I watched it in an IMAX theater and feel it was not at all soft. In any event, it was good enough to gross $1B.

 

While the focus now seems to be only on resolution, there are a multitude of other factors (speed, DoF, color, flare, chromatic abberation, bokeh, mechanical, etc.) that are arguably as or more important than resolution in the choice of a lens.

 

Of crucial importance for the BMCC is the lack of fast short focal length lenses for the non-electronic MFT mount. I often choose a 17mm f/2.8 for Full Frame. That translates to 7.5mm on the BMCC. Perhaps there are a few rectilinear (non-fisheye) 7.5mm T1.3 Super 35 lenses I haven't heard of.

 

Whether or not a cropped 8mm T1.3 Zeiss Ultra 16 will turn out to be sharper or softer than, for example, a non-cropped 8-11mm f/4.5 Sigma remains to be seen. But because of the smaller format size, Super 16 lenses have always tended to be sharper than Super 35, my bet is on the Ultras.

 

In the mean time, don't substitute anyone elses eyes for your own. As I pointed out earlier, it is quite straightforward to download a few BMCC .dng frames, resample, crop, sharpen, and see for yourself how much of a resolution penalty a crop imposes.

 

Cheers.

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