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Author Topic: BW Digital Back with self made autochrome color filter  (Read 4050 times)

Mustafa Umut Sarac

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BW Digital Back with self made autochrome color filter
« on: May 29, 2009, 09:34:22 pm »

I am researching autochrome technology and its like a television screen. There are 3 colors colored powder and you take color pictures with black and white film with the help of this layer. It is about taking pictures with millions of little rgb filters and watch color film with the same powder filter.

I want to do it with bw digital back and put a inkjet printed color filter - tiny rgb dots -

Is there a very cheap only bw back at the market ?

Best ,

Mustafa Umut Sarac

Istanbul
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Anders_HK

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BW Digital Back with self made autochrome color filter
« Reply #1 on: May 30, 2009, 12:20:44 am »

Quote from: Mustafa Umut Sarac
I am researching autochrome technology and its like a television screen. There are 3 colors colored powder and you take color pictures with black and white film with the help of this layer. It is about taking pictures with millions of little rgb filters and watch color film with the same powder filter.

I want to do it with bw digital back and put a inkjet printed color filter - tiny rgb dots -

Is there a very cheap only bw back at the market ?

Best ,

Mustafa Umut Sarac

Istanbul
[font="Comic Sans MS"][/font]

Hi

Please do not use bold, it is like shouting   .


I do not know that a B&W digital back was ever made, but someone else might.

Could an option be to use a red filter, e.g. Hoya 25A, and to in processing convert to B&W?

Regards
Anders
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ThierryH

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BW Digital Back with self made autochrome color filter
« Reply #2 on: May 30, 2009, 12:30:30 am »

FYI:

ALL digital backs (CCDs) are basically monochrome, giving a B&W image. The very first generation of digital backs was using RGB filters in front of the lens (or behind) with 3 exposures in a raw, to get the necessary color information for each basic color channel and to be able to build up a color image.

Nowadays all digital backs are using a pattern of thiny little filters over the pixels, basically to do the very same: to have the color information for the 3 basic color channels R, G and B and to be able to build up a color image.

Best regards,
Thierry
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michaelnotar

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BW Digital Back with self made autochrome color filter
« Reply #3 on: May 30, 2009, 04:40:44 am »

Quote from: ThierryH
FYI:

ALL digital backs (CCDs) are basically monochrome, giving a B&W image. The very first generation of digital backs was using RGB filters in front of the lens (or behind) with 3 exposures in a raw, to get the necessary color information for each basic color channel and to be able to build up a color image.

Nowadays all digital backs are using a pattern of thiny little filters over the pixels, basically to do the very same: to have the color information for the 3 basic color channels R, G and B and to be able to build up a color image.

Best regards,
Thierry


yes all true, but i hear it lowers image resolution... there has been monochromatic backs made, phase one can custom order them, which do not have the bayer layout i think its called with the RGBRGB pixel layout. i saw a 16MP sq one and a 39MP rectangular b/w back. check out digilloyd.com i think it is. they are not cheap, they are more since they are custom made in a very small production run.

the 16MP b/w back is supposed to have the resolution of about a regular 30-39MP color image converted to b/w. that being said, i would like to see such an example.
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michaelnotar

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BW Digital Back with self made autochrome color filter
« Reply #4 on: May 30, 2009, 04:48:30 am »

BTW for those who dont know, heres what i can find about the process...interesting... my hat is off to you.

http://en.wikipedia.org/wiki/Autochrome
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Kumar

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BW Digital Back with self made autochrome color filter
« Reply #5 on: May 30, 2009, 05:10:52 am »

See http://www.mega-vision.com/products/Mono/Mono.htm for a monochrome back. I've never actually seen one, though.
 
Cheers,
Kumar
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ThierryH

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BW Digital Back with self made autochrome color filter
« Reply #6 on: May 30, 2009, 06:23:53 am »

yes, absolutely right, Michael.

That is simply because each pixel can register only the color information for the filter type it is fitted with on its top: either Red, or Green or then Blue, never more. Thus the resolution takes its toll.

Therefore also the reason why multishot backs exist: each pixel registers the light for R, for G and for B, actually with Sinarbacks the Green is even registered twice (twice as many green pixels, as red or blue pixels).

Best regards,
Thierry

Quote from: michaelnotar
yes all true, but i hear it lowers image resolution..

edited for syntax correction
« Last Edit: May 30, 2009, 06:26:14 am by ThierryH »
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CBarrett

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BW Digital Back with self made autochrome color filter
« Reply #7 on: May 30, 2009, 09:18:48 am »

What could be really nice about this, is that a dedicated monochrome back could produce B+W images with absolutely no interpolation.  If you thought your P45+ produced sharp images before!  I've never worked with a multishot back, but I imagine that's the quality you would get.

Just for kicks, I've been wanting to try out Digichromatography by shooting b+w negs through R/G/B filters and then turning each of those images into a channel.  My laziness trumped my geekiness in the long run.
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Kumar

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BW Digital Back with self made autochrome color filter
« Reply #8 on: May 30, 2009, 09:26:11 am »

Quote from: CBarrett
Just for kicks, I've been wanting to try out Digichromatography by shooting b+w negs through R/G/B filters and then turning each of those images into a channel.  My laziness trumped my geekiness in the long run.

See some great pictures here: http://www.largeformatphotography.info/for...ead.php?t=48583

Cheers,
Kumar
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Anders_HK

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BW Digital Back with self made autochrome color filter
« Reply #9 on: May 30, 2009, 02:27:38 pm »

And... using a filter that is used for B&W film such as the Hoya 25A B&W contrast filter on digital as I suggested above does exactly what on a bayer? It limits to capturing red tones and not much other color info, thus color info interpolated as "red". It does not increase resolution, but I have found it very very interesting to play with on my Leica M8.

Any thoughts?

Anders
« Last Edit: May 30, 2009, 02:28:16 pm by Anders_HK »
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