doctorbeat
newbie
Reged: 02/02/2008
Posts: 8
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I'm wondering about the feasibility of converting a digital compact to shoot just black and white.
It seems to me that there would be several advantages to a dedicated B&W digital camera.
It seems from what I have read on the subject that colour digital sensors need a bayer filter and a moire filter, and then the image needs unsharp masking to correct the effects of the filters.
If a camera had just the sensor (and maybe an IR filter) then the images should be of better quality, and the camera would be able to operate at the equivalent of much lower iso ratings (ie less noise)
I have recently bought a new samsung NV10 as a daily carry camera. (I did want the NV7, but I got an offer I couldn't refuse on the NV10, plus it's easier to slip into a pocket)
That means that my old compact (a Rollei badged thing) is now redundant.
I have already converted an old compact to a dedicated IR camera with fantastic results, and I still regret giving it away....
I wonder if it is possible to remove the bayer filter and the moire filter from the CCD of my spare camera to achieve my goal of a 'proper' B&W camera?
Has anyone heard of this being done, or have any ideas/ information that may help me?
I'd be more than happy to contribute a series of photos of the process to the forum if I manage to get this working.
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beejaybee
Marvin
Reged: 18/07/2007
Posts: 4117
Loc: Really Here In Name Only
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Quote:
I wonder if it is possible to remove the bayer filter and the moire filter from the CCD of my spare camera
Is it really necessary to remove the Bayer filter? Can you not just sum the outputs in the ratio R:G:B = 1:2:1?
I rather think that you would need to tinker with the software as well as the hardware to get the full benefit of removing the Bayer filters - if that can even be done; are the filters an integral part of the microlenses, or is there a filter layer between the microlenses and the sensor substrate, in which case removing or substituting it would have to be done very carefully to avoid upsetting the alignment of the microlens array with respect to the sensor sites, which is critical to the efficiency of the system.
There are lots of different monochrome CCD/CMOS sensors available, if you want to start from scratch; which may possibly be a better place to start from, if you want to realise the higher quantum efficiency of a monochrome sensor.
But, if you just want lower noise, perhaps colour to monochrome conversion starting from a sensor with bigger photosites (i.e. a DSLR) would be the most economic approach.
In any case I don't see what possible benefit there would be in removing the moire (anti-alias) filter, unless you have some alternative method of processing out aliasing artifacts.
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doctorbeat
newbie
Reged: 02/02/2008
Posts: 8
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You're probably right about the software side of things.The impression I got from what I've read (and I haven't found much) is that the microlenses might not be necessary in a bayerless B&W sensor (but I have no idea if this is true), and that the moire filter is there to correct the effects of the bayer, so should also be unnecessary.
I'm not really interested in doing this for fantastic image quality, just more of an experiment to see if it can be done. The idea that the bayer filter 'gets in the way' and has to have its effects corrected also intrigues me, and it would be interesting if I was able to turn my crappy point and shoot into a very high resolution camera capable of producing good images in very low light situations.
I know it's better to shoot colour and then convert to B&W than use a camera's inbuilt B&W setting, but wouldn't it be nice to have a digital camera that behaved like a 'real' camera loaded with B&W film? You'd be able to use filters too.
I know I could just use a film camera, but I'm afraid I've become a bit of a digital addict. Although I do enjoy the developing process, I just can't argue with the convenience of digital.
I'd be the first to admit that I'm not a very accomplished photographer, and the throwaway nature of digital has in my case improved my photography simply due to the law of averages!
I do have a DSLR, but I've found that I tend to leave it at home. That's why I bought the Rollei- it's my constant companion, and I guess the first rule of photograpy is to make sure you have a camera!
After my experiment of carrying a compact constantly, I found that I was actually taking some photos for a change so I decided to get a nicer model.
I wanted the samsung NV7, but I got a really good deal on an NV10.
Personally I think 10Mp is too high for a compact, and I'm a little worried about the noise generated by fitting so many pixels on a compact's sensor, but as you rightly point out, I have my DSLR if I need better quality.
I guess I'm just pining for the days of old with rangefinders, tlr's and B&W film, but now I have been spoiled by digital so I want the best of both worlds.
I think my Ideal cameras would be a digital B&W only Leica rangefinder, and a digital TLR.
Nowadays it seems that compacts are losing their viewfinders too, which is a real shame.
One distinct advantage of a dedicated B&W compact would be that the LCD would also display in B&W, which I think would help with composition.
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beejaybee
Marvin
Reged: 18/07/2007
Posts: 4117
Loc: Really Here In Name Only
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Quote:
The impression I got from what I've read (and I haven't found much) is that the microlenses might not be necessary in a bayerless B&W sensor (but I have no idea if this is true), and that the moire filter is there to correct the effects of the bayer, so should also be unnecessary.
My understanding is that the microlens array is necessary in order to obtain a reasonable quantum efficiency. Without it, a very large proportion of the incident light would hit a portion of the sensor chip which was not sensitive to anything.
Some sensors also use the microlens array in a clever way - the microlenses towards the edges of the sensor are bigger and/or angled so as to reduce the effect of vignetting.
The moire pattern in the individual RGB channels is indeed twice the size that it is in the summed output, but nevertheless aliasing ("steppiness" of an angled line) is an inherent feature of all sensors which use regular tilings of photosites. I quite agree that the necessary filtering could be done in software on the PC after downloading the image from the camera, if you can get hold of the raw data - if the camera software has processed the sensor output by a lossy algorithm (e.g. JPEG output) then the opportunity is gone.
Quote:
but wouldn't it be nice to have a digital camera that behaved like a 'real' camera loaded with B&W film? You'd be able to use filters too.
Sure. But - fiddling around with my Canon 5D and a bunch of "monochrome" filters screwed into the threads at the front end of the lens- it looks like you can use the filters quite effectively even with the monochrome conversion built into the camera. Deep red does not work as well as it should do - the IR blocking filter is actually removing some of the visible red as well - anyone who has tried taking photographs of nebulae which shine by hydrogen alpha emission (656.28 nm) will be aware of the weak response of the sensor in most digital cameras. As you've already found, removing the IR blocking filter isn't too hard - they're actually intended to be replaceable, with filters with different transmission characteristics available for different specialist applications - but the microlens array & coloured filters used by the Bayer matrix are much more intimately linked with the sensor substrate.
It is of course necessary to disable the camera auto white balance when using coloured filters - on the 5D just set white balance to "daylight" - actually mine is set that way all the time, I do any necessary white balance correction in the raw converter software after downloading the images.
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That's why I bought the Rollei- it's my constant companion, and I guess the first rule of photograpy is to make sure you have a camera!
Absolutely. Incidentally I usually carry an old manual compact film camera (Rollei B35, usually loaded with HP5+) even when I am carrying my Canon 5D, and certainly when I leave it at home.
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Nowadays it seems that compacts are losing their viewfinders too, which is a real shame.
Absolutely agree. I find it very hard to compose on a screen held at arm's length, and even harder to keep the horizon level when shooting that way. Having to carry a tripod - and a black cloth to keep sunlight off the LCD screen - seems to negate the only real advantage a compact camera has - portability!
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One distinct advantage of a dedicated B&W compact would be that the LCD would also display in B&W, which I think would help with composition.
I don't find any particular problem with composing in monochrome - what I do have a problem with is visualizing what the effect of the conversion to monochrome will be, especially when not using a deep red filter! I find looking around me (not necessarily through the camera viewfinder) with a green filter held to the eye helps ... perhaps observing a colour LCD through a filter similar in colour to the effect you want would help.
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doctorbeat
newbie
Reged: 02/02/2008
Posts: 8
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Thanks for your replies, and yes, it seems like my idea wasn't as straightforward as I thought!
Never mind....
When I said that a B&W viewfinder would make composition easier, I was in error really. What I meant was what you say about visualisation of the image in mono. I'm better at it than I used to be, but for a rank amateur like me, the less guesswork I have to do the better, and a B&W viewfinder would be a godsend.
I do sometimes pop my camera into B&W mode just to have a look before I shoot in colour, but my DSLR (Nikon D50) doesn't have a B&W setting, so I can only do this on my compact.
The main thing I hate about not having a viewfinder is the lack of stability. I try to avoid using the flash on my compact as much as possible, but holding the thing at arm's length is not very stable, plus one point of contact (the face pressed to the camera) is absent.
This means that I often have to use flash if there isn't much light, as a slower shutter speed would make a blurry image, so the lack of an optical viewfinder really does have a large impact on the quality of my pictures.
This was one of the reasons I was hoping to make this B&W conversion. The impression I got was that the sensor would be far more sensitive, and therefore I would be able to take more shots without resorting to the on- camera flash.
I suppose you could liken the lcd screen to the viewfinder on a TLR, but TLR's can be braced against the chest or some other body part, while this isn't really practical with a digital compact.
I was very surprised when Leica came out with their rebadged Panasonic cameras with no optical viewfinder- what's the world coming to?!
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zx9
old hand
Reged: 22/06/2007
Posts: 786
Loc: London
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Quote:
I suppose you could liken the lcd screen to the viewfinder on a TLR, but TLR's can be braced against the chest or some other body part, while this isn't really practical with a digital compact.
I have found that by holding the G9 and tensioning the neck strap, pushing the camera away from myself I can hand hold at very low shutter speeds. It had occured to me that it is a stance not unlike steadying a TLR by pulling down on the neck strap.
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Regards
ZX9 (Keith)  
My Flickr Pictures
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doctorbeat
newbie
Reged: 02/02/2008
Posts: 8
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Yes indeed, I do the same thing with the wrist strap on my compact.
Now you mention it, that's another thing that's gone south that I miss- neck straps instead of wrist straps.
I know cameras have got smaller, but a neck strap with two anchor points on the camera is a really good aid to holding the thing still.
I'm not old enough to really remember when rangefinders were in their heyday, but when I was a kid I had your usual compact camera.
I remember asking my dad why some of my photos had turned out so bad, and he explained to me about cameras that required more thought and input from the photographer (ie manual settings) that were harder to use but would give better pictures if used correctly.
At the time, an SLR was not a camera one could buy for a child as they were pretty expensive, but he did get me a Voightlander Vitoret, which I still have.
This was the camera that got me hooked on photography, and is also the type of camera that I miss.
It seems that features that were on the cheapest cameras back then are now only available for enormous prices in the new digital age.
I don't want to spend loads of money on a Leica or the Epson rangefinder because I use my compact to go places I wouldn't take my SLR.
I have a cheap compact precisely because I won't cry if I lose it!
It's just a shame that you don't seem to be able to get a low priced compact with a two point neck strap, an optical viewfinder and maybe (dare I ask?) an eveready case. None of these features are expensive to produce, they just aren't fashionable.
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Benchista
Wich Tyler
Reged: 11/08/2000
Posts: 36162
Loc: Everywhere and nowhere, baby
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Quote:
I have a cheap compact precisely because I won't cry if I lose it!
It's just a shame that you don't seem to be able to get a low priced compact with a two point neck strap, an optical viewfinder and maybe (dare I ask?) an eveready case. None of these features are expensive to produce, they just aren't fashionable.
Thank goodness as regards the never-ready case!
I've got several digital compacts (none of them all that new) and only one - the smallest - doesn't have an optical viewfinder. That one is very small, fits nicely into a pocket and I certainly wouldn't want a neck strap for it. In fact only the oldest one I own is big enough for a neck strap (it's a similar size and weight to a Vitoret) - and it actually has one. The others are pocketable, and that suits me much more than a case or a neck strap.
Quote:
It seems that features that were on the cheapest cameras back then are now only available for enormous prices in the new digital age.
Maybe, but the converse is also true - even my absolute basic pocket camera has a choice of metering modes, for example.
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Nick
www.nbrphoto.com
Light and Shade II - the new blog
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Mojo_66
Carpal \'Tunnel
Reged: 25/05/2006
Posts: 3083
Loc: Lancs
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Quote:
I'm wondering about the feasibility of converting a digital compact to shoot just black and white.
It seems to me that there would be several advantages to a dedicated B&W digital camera.
It seems from what I have read on the subject that colour digital sensors need a bayer filter and a moire filter, and then the image needs unsharp masking to correct the effects of the filters.
If a camera had just the sensor (and maybe an IR filter) then the images should be of better quality, and the camera would be able to operate at the equivalent of much lower iso ratings (ie less noise)
The Sigma SD14 has a Foveon sensor, doesn't tend to suffer from moire and so doesn't have an AA filter. It does have an IR filter for normal use, but this is removable if you want to shoot IR, which apparently is easily possible to do hand held, I haven't tried it with mine yet though. Images from it printed to A4 look very smooth up to ISO400, much smoother than I get with film, as long as you don't underexpose, then you start getting some green blobs in there, with mono though you wouldn't notice this. The same sensor has just become available in the Sigma DP1 compact.
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http://www.flickr.com/photos/mojo_black/
Edited by Mojo_66 (05/02/2008 16:21)
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Rhys_Hardwick
enthusiast
Reged: 12/04/2007
Posts: 207
Loc: Cardiff, Wales, UK
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I have skim read the above, and sorry if someone has already said this. The huge advantage of removing the bayer array and having a luminosity-only sensor is that you can gather much more light. If you take R G and B filters as reducing light from 2-3 stops, you can effectively gather 2-3 stops more light, therefore increasing the effective sensitivity of the sensor.
Furthermore, each photosite can be mapped to one pixel, increasing pixel count by 4-fold.
These are the main advantages I can see.
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Rhys Hardwick
www.rhyshardwick.co.uk
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beejaybee
Marvin
Reged: 18/07/2007
Posts: 4117
Loc: Really Here In Name Only
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Quote:
If you take R G and B filters as reducing light from 2-3 stops, you can effectively gather 2-3 stops more light, therefore increasing the effective sensitivity of the sensor.
True, but I rather suspect 2-3 stops is a gross overestimate of the loss. Nevertheless for the highest quantum efficiency astronomers use monochrome sensors - making seperate exposures with R G & B filters when necessary for colour work.
Quote:
Furthermore, each photosite can be mapped to one pixel, increasing pixel count by 4-fold.
Not so, the pixel count is fixed ... the trick is that, with a Bayer filtered sensor, the "missing" intermediate pixel values (75% of them for the R & B channels, 50% for the G channel) are interpolated from the data which is available.
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doctorbeat
newbie
Reged: 02/02/2008
Posts: 8
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Quote:
I have skim read the above, and sorry if someone has already said this. The huge advantage of removing the bayer array and having a luminosity-only sensor is that you can gather much more light. If you take R G and B filters as reducing light from 2-3 stops, you can effectively gather 2-3 stops more light, therefore increasing the effective sensitivity of the sensor.
Furthermore, each photosite can be mapped to one pixel, increasing pixel count by 4-fold.
These are the main advantages I can see.
Yep, that was what made me want to do this.
It would like having a super fast lens and a higher pixel count with less 'wizardry' necessary to correct the image afterwards.
Benchista, I take your points about the eveready case and the neck strap, but i would still love these features on a tiny pocketable camera.
My compact has a shutter that closes when the lens is retracted to protect it, but it is really flimsy and lets pocket dust in. I would much prefer a case that could be deployed as fast as an eveready type, I just hate those velcro- flapped 'purses'.
I would like two attachment points to allow a neck strap to be used because as well as being a good brace, sometimes it's nice to just let go of the camera and let it drop to my chest. It's then ready for the next time I want to use it.
The neck strap could be as thin as the wrist strap, I didn't mean a big wide one like on SLR's.
I suppose there's no reason why I couldn't use a neck lanyard that attaches at one point only...
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beejaybee
Marvin
Reged: 18/07/2007
Posts: 4117
Loc: Really Here In Name Only
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Quote:
I take your points about the eveready case and the neck strap, but i would still love these features on a tiny pocketable camera.
OK, you would need a big pocket, but in the current AP there is an advertiser offering an ever-ready type case for the Canon G9!
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tazio35
member
Reged: 16/10/2007
Posts: 174
Loc: Cromer, Norfolk
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Quote:
I would like two attachment points to allow a neck strap to be used because as well as being a good brace, sometimes it's nice to just let go of the camera and let it drop to my chest. It's then ready for the next time I want to use it.
The neck strap could be as thin as the wrist strap, I didn't mean a big wide one like on SLR's.
I suppose there's no reason why I couldn't use a neck lanyard that attaches at one point only...
I used the thin neck strap that came with my Holga on my Minolta Hi-Matic F. I tried using both attachment points, but the camera tended to flip over and was uncomfortable. I then clipped both ends of the strap to one point and it made a huge difference.
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Adam
http://www.flickr.com/photos/34624508@N00/
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AJUK
Reged: 22/03/2005
Posts: 2626
Loc: UK
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I think a Dedicated B&W DSLR would be more worth while.
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Al
[Insert clever comment here]
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bobrobert
newbie
Reged: 10/11/2006
Posts: 3
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unfortunatley you could only use it in jpeg mode As to seeing in black&white I think that RGB company does a device that you can place in front of your eye and you see the world in black&white
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Fen
BAD WOLF
Reged: 12/03/2002
Posts: 19392
Loc: Currently Unknown!
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Who are "RGB company" ?
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Fen.
- Fen's Flickr Fotos -
"One good photograph does not a photographer make."
Edited by Fen (11/03/2008 11:11)
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Benchista
Wich Tyler
Reged: 11/08/2000
Posts: 36162
Loc: Everywhere and nowhere, baby
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I suspect it's SRB...
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Nick
www.nbrphoto.com
Light and Shade II - the new blog
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Burgy
Grateful not to have one
Reged: 13/04/2001
Posts: 5184
Loc: This far, from beating 7 shade...
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You could always see if you could find a used Kodak DCS1m
Kodak EOS-DCS 1m (Monochrome, 6 megapixel, based on Canon EOS-1n)
From memory it is limited to 200ISO, and the technology is a little old 
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Cheers
Burgy BSRIPN, BSc, DSO and Bar (now open 24/7).
it's not what you've got, its who you do it to
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