MONOCHROME Pentax K-1

In the beginning of 2022 I had opportunity to get very cheap full frame DSLR in working condition with 36 mpix sensor - same sensor used in Pentax K-1, Sony a7R, Nikon D800/810. I used it for my monochrome conversion (debayering) experiment and first attempt was successful. This motivated me to try Pentax K-1 conversion because I am Pentax shooter and this camera has many good functions as well as in-body image stabilization. Unfortunately my attempt in April 2022 was unsuccessful and I hesitated quite long to try another K-1. Until October 2022.
Probably many of you know advantages of monochrome sensor compared to stock sensor:
- resolution increase (x2,25): sensor still has 36 mpix but is able to produce details which can be get from about 80 mpix stock sensor;
- sensitivity increase about 0,7-1 stop (my observation is more modest - 0,5-0,7 stop, but some sources claim +1 stop as an average);
- much better noise profile at higher ISOs (advantage about 1,5-2 stop). IMO ISO 6400 look very very beautiful and now I use max Auto-ISO 25600 without fear.

I like the idea of shooting monochrome only. Starting from early 2021 when I converted Pentax K200D with 10 mpix CCD sensor I like monochrome even more than color.

Pentax K200D monochrome

First FF 36 mpix monochrome sensor (D800)

Pentax K-1 monochrome (36 mpix) debayered

Medex, you have some really beautiful photos, and I'm able to see what you mean. They look like the difference between my old TV and the newer 4K TV.

Thanks for sharing.

Tom W

Those are wonderful and have a great look to them, and obviously well planned out.

I am of the opinion that it is just as important to show off our failures so that others can learn from them. Can you tell us about how your conversion went wrong?  Did you document somewhere the conversion process?   ( That can be a separate thread, obviously, but I am curious as I am interested in doing a multi-spectral conversion which is 98% the same mess. )

So you have a sensor with rows going
Red Green Red Green
Green Blue Green Blue.

You remove the bayer filter - but the camera still thinks that 1,1 is red, 1,2 is green, 2,1 is green, 2,2 is blue and it outputs a raw with 4 pages for R, G1, B, G2, or a very odd debayer'd JPEG (which will also appear in live view).

What do you use to convert the files to a 36MP mono ? I'm assuming there is no firmware hack to do it.

TomWret wrote:

Medex, you have some really beautiful photos, and I'm able to see what you mean. They look like the difference between my old TV and the newer 4K TV.

Thanks for sharing.

Tom W

Thank you

• BobORama wrote:

Those are wonderful and have a great look to them, and obviously well planned out.

I am of the opinion that it is just as important to show off our failures so that others can learn from them. Can you tell us about how your conversion went wrong? Did you document somewhere the conversion process? ( That can be a separate thread, obviously, but I am curious as I am interested in doing a multi-spectral conversion which is 98% the same mess. )

Multispectral conversion? Is it the same as full spectrum? If yes, then your choice is much much easier to do. You don't need to remove color filter array from sensor surface and even go beyond sensor protective glass. Simple removal of UV/IR-cut filter makes your sensor full spectrum (or almost full spectrum, because UV part is still blocked by protective glass).

James O'Neill wrote:

So you have a sensor with rows going
Red Green Red Green
Green Blue Green Blue.

You remove the bayer filter - but the camera still thinks that 1,1 is red, 1,2 is green, 2,1 is green, 2,2 is blue and it outputs a raw with 4 pages for R, G1, B, G2, or a very odd debayer'd JPEG (which will also appear in live view).

What do you use to convert the files to a 36MP mono ? I'm assuming there is no firmware hack to do it.

Yes, you are right - camera does not know that sensor has no color filters. Therefore almost all white balance modes give pinkish jpeg preview on the screen. But I set custom white balance using white paper and preview now looks gray-toned. I also switch to Monochrome mode to discard all possible color "additives".

So, now jpegs are black and white. But I do not shoot jpeg at all. RAW only. Then I import raw files into editing software (Raw converter = e.g.Lightroom) for storage. But editing software applies demosaicing which degrades details. It is not good if you like max details and shoot with dedicated mono camera. To avoid demosaicing and get pure monochrome, Monochrome2Dng converter is used. It produces another DNG file which is treated by Lightroom as monochrome and demosaicing is not applied.

Medex wrote:

James O'Neill wrote:

So you have a sensor with rows going
Red Green Red Green
Green Blue Green Blue.

You remove the bayer filter - but the camera still thinks that 1,1 is red, 1,2 is green, 2,1 is green, 2,2 is blue and it outputs a raw with 4 pages for R, G1, B, G2, or a very odd debayer'd JPEG (which will also appear in live view).

What do you use to convert the files to a 36MP mono ? I'm assuming there is no firmware hack to do it.

Yes, you are right - camera does not know that sensor has no color filters. Therefore almost all white balance modes give pinkish jpeg preview on the screen. But I set custom white balance using white paper and preview now looks gray-toned. I also switch to Monochrome mode to discard all possible color "additives".

So, now jpegs are black and white. But I do not shoot jpeg at all. RAW only. Then I import raw files into editing software (Raw converter = e.g.Lightroom) for storage. But editing software applies demosaicing which degrades details. It is not good if you like max details and shoot with dedicated mono camera. To avoid demosaicing and get pure monochrome, Monochrome2Dng converter is used. It produces another DNG file which is treated by Lightroom as monochrome and demosaicing is not applied.

A-ha! That was the missing piece.

Medex, I've seen you previous equally fantastic BW shots from converted sensors. It's fascinating and the BW images are fantastic. Well done to you !

Personally I'd be too scared to attack a fully functioning decent camera in case i wrecked it. But - a monochrome K5II is something I would love . . .

Cheers,

Rod

Lessiter wrote:

Medex wrote:

To avoid demosaicing and get pure monochrome, Monochrome2Dng converter is used.

Have you tried http://rawtherapee.com/ ?

Raw tab (mosaic icon) > Demosaic Method > Mono (or perhaps none)

Yes. I tried Rawtherapee and monochrome demosaic method, but its interface is too difficult to me and I don't like it. Just my preference

This is a very convincing argument for getting a camera converted.

I have to admit I love colour but what you have achieved here is most impressive - so detailed and obviously professionally shot.

Those are all exquisite, and the sepia tone you applied on the last one is the icing on the cake.

Rod Herdman wrote:

Medex, I've seen you previous equally fantastic BW shots from converted sensors. It's fascinating and the BW images are fantastic. Well done to you !

Personally I'd be too scared to attack a fully functioning decent camera in case i wrecked it. But - a monochrome K5II is something I would love . . .

Cheers,

Rod

I wrote DM to you.

timo wrote:

This is a very convincing argument for getting a camera converted.

I have some already converted if you like (in good shape and tested)

ozdean wrote:

I have to admit I love colour but what you have achieved here is most impressive - so detailed and obviously professionally shot.

Thank you. I shoot not often but like planned photoshoots more, especially for monochrome

Mark Ransom wrote:

Those are all exquisite, and the sepia tone you applied on the last one is the icing on the cake.

Sepia toning is the way of postprocessing I use in last months

This is beautiful. I kind of wish to have a dedicated monochrome K-1 to use with Takumar lenses. Is the conversion technically challenging?