We need a low pass filter

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Scott Pultz

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We need a low pass filter

PostMon Mar 04, 2013 3:05 am

I hope that Mosaic Engineering comes through with an OLPF for this camera. Although I love the images that I am capturing, I all too often get footage with difficult to fix moire and aliasing.

For example here is a tree captured in focus at F5.6. You can see the aliased mess inside of the branches:
35mm_f5_6.jpg
35mm_f5_6.jpg (256.72 KiB) Viewed 3066 times


If I switch to F22 and let diffraction blur set in, the details are blurred enough to give a pleasing image. Of course this isn't a solution. Ideally the OLPF would blur just the right amount.
35mm_f22_diffraction.jpg
35mm_f22_diffraction.jpg (191.75 KiB) Viewed 3066 times


All of the other camera limitations I can so far deal with. However avoiding shots due to aliasing or trying to fix them in post is less than ideal :) It's worth it to shoot in RAW though!
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Zack Wilson

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Re: We need a low pass filter

PostMon Mar 04, 2013 4:07 am

I've been talking a lot with Mosiac Engineering about it. They're trying to get the BMCC filter out as soon as possible and are working with their manufacturing company to try to get it in with this production round. I'll keep you guys posted as anything more comes up.
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Felix Steinhardt

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Re: We need a low pass filter

PostMon Mar 04, 2013 12:32 pm

I´m sure mosaic will get this filter out before the camera is delivered to most of the people...
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Noel Sterrett

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Re: We need a low pass filter

PostMon Mar 04, 2013 1:19 pm

I am quite pleased that the camera has no OLPF.

Although not strictly a Bayer pattern sensor, Fuji dropped their OLPF. Then Nikon followed with the D800E.

And now Nikon again: "The innovative sensor design delivers the ultimate in image quality by defying convention; because of the high resolution and advanced technologies, the optical low pass filter (OLPF) is no longer used. Using NIKKOR lenses, the resulting images explode with more clarity and detail to take full advantage of the 24.1-megapixel resolution achieved with D7100’s DX-format CMOS sensor."

From Vaseline to ProMist to stockings behind the lens, lens/filter combinations have been used for decades to soften images. If the OLPF is baked-in, you have no choice, but without it there are many and all can be adjusted to fit the scene.

The MFT version is particularly suited to this approach, since filtering could be placed behind the lens and supported by the adapter (Metabones Speedbooster + OLPF). It may also be possible to fashion a variable OLPF, much like a variable ND.

With Bayer pattern sensors, all OLPF's are a comprise since green resolution is twice that of red and blue. Leaving the blur to the user is a good thing.

Cheers.
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Randy Walters

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Re: We need a low pass filter

PostMon Mar 04, 2013 3:24 pm

I'm in complete agreement with Noel. It's far, far better that we have the capability to utilize the sensor's sharpness than to have that capability taken away by a permanently built-in OLPF.

We now have the responsibility to address that sharpness - and any undesired artifacts - in the manner we choose. We will soon be able to utilize the Mosaic filter, and can use any of the other techniques Noel mentioned. This is the best possible outcome, as it leaves the widest range of picture quality available.

You can bet that if BMD *had* put in a permanent filter, people would be screaming and moaning about ways to mod the camera by ripping it out. I'll undoubtedly get one of the Mosaic filters to have on hand for those situations when it's needed, but I love the way the camera looks now, and wouldn't want to give that up.
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Manu Gil

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Re: We need a low pass filter

PostTue Mar 05, 2013 12:25 pm

Noel Sterrett wrote:I am quite pleased that the camera has no OLPF.

Although not strictly a Bayer pattern sensor, Fuji dropped their OLPF. Then Nikon followed with the D800E.

And now Nikon again: "The innovative sensor design delivers the ultimate in image quality by defying convention; because of the high resolution and advanced technologies, the optical low pass filter (OLPF) is no longer used. Using NIKKOR lenses, the resulting images explode with more clarity and detail to take full advantage of the 24.1-megapixel resolution achieved with D7100’s DX-format CMOS sensor."

From Vaseline to ProMist to stockings behind the lens, lens/filter combinations have been used for decades to soften images. If the OLPF is baked-in, you have no choice, but without it there are many and all can be adjusted to fit the scene.

The MFT version is particularly suited to this approach, since filtering could be placed behind the lens and supported by the adapter (Metabones Speedbooster + OLPF). It may also be possible to fashion a variable OLPF, much like a variable ND.

With Bayer pattern sensors, all OLPF's are a comprise since green resolution is twice that of red and blue. Leaving the blur to the user is a good thing.

Cheers.


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