Diy Digital Rf - Is It Possible?

Dear Brian,

Personally, I prefer B/W..."The colour of photography".

I didn't mention B/W-only in the very beginning only because I am tired of being jumped on, and have the discussion hijacked by a few self-proclaimed experts lurking in these forums.
 
Brian Sweeney said:
I think the answer might surprise you. Especially if you can do this for $1,000. The Mosaic filter robs 50% of the light and adds an extra layer in front of the sensor. That is in addition to the 50% that the IR filter robs from the sensor. A lot of people pay as much to get a DSLR converted to Infrared as you are projecting the cost of the Back. When the DCS200 was new, I special ordered one in Infrared for an extra $4,000 and we also ordered a color camera. Combined cost for the two was over $20,000. How times have changed.

Getting rid of the Mosaic filter also does away with the need for Anti-Aliasing hardware and software.
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I don't have the fine data on the DCS.

If: "...the Mosaic filter robs 50% of the light and adds an extra layer in front of the sensor. That is in addition to the 50% that the IR filter robs from the sensor...", then removing both in B/W implementation will gain ~2 stops in sensitivity...making it a nominal ISO 50? Worth thinking about.

Removing the anti-aliasing hardware will also match a much touted M8/9 feature...:D
 
Back doors are 'mostly' interchangeable between M1/M2/M3/M4/M5/M4-P/M4-2. (Some early M3s have a slightly different fit.) The M6 and M7 backs have electrical contacts (ISO is set on the back) and may or may not be physically compatible with earlier backs other than these contacts. Not sure about the MP.
 
So you have a fixed ISO back and set your handheld meter at whatever ISO you want and let the latitude of the sensor cover the exposure errors? Or just don't worry about metering and hope something comes out (no LCD to chimp with)?
 
No, you set ISO on your new digital back. It's communicated to the camera only on the M6 and M7, which is fine because only those have a builtin meter anyway. (Well, except us M5 people but as usual we're likely to be screwed anyway ;)).

If they're not 100% exchangeable between the M1-M5 and the M6/M7, it would be no problem I think to build the digital back with exchangeable frames that serve as fittings for the different bodies. It's just mechanical pieces. Putting the thing behind a Nikon F2 would then only be a matter of building a F2 back door with a fitting for the digital back, same as for any other camera.
 
"Such a Digital Film package could be nominally rated at ISO 200 with much latitude in the underexposure side, just like transparency films [whether you meter or not]."

Here is the quote I must have misunderstood.
 
If the native ISO of a sensor with a Mosaic Filter and IR cut-off filter is ISO 200, then the Monochrome version of the Sensor would be ISO 400, and a Sensor without the Mosaic Filter and without the IR cut filter would be ISO 800. The Native ISO of the DCS200c was 50, and mine without the Mosaic Filter and without the IR Cutoff filter was ISO 200. Just call me Darth Geek.
 
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Pickett Wilson said:
So you have a fixed ISO back and set your handheld meter at whatever ISO you want and let the latitude of the sensor cover the exposure errors? Or just don't worry about metering and hope something comes out (no LCD to chimp with)?
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That's basically what you're doing in every digital camera anyway; can't really change the quantum efficiency or storage capacity of the sensor.

[edit/addition]
@Brian: Shouldn't that be mostly from the removal of the colour filter, since with that you're throwing away two thirds of (white) light at every photo site? A good IR-filter doesn't block more than some percent, at most, of the visible range. Might worsen the situation further at the edges though I guess.
 
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I guess the idea is to put the minimum electronics into the back to get the raw data off the sensor to the SD card, and then have the photographer do everything else with an outboard program on his computer. How many folks besides extreme geeks would want to have to do so much manipulation to every image? Or would understand how?
 
The ISO rating of a film is only a manufacturer's suggestion. Some are more optimistic than others.

We can fine tune it the way we want the image to look...overexposure/underdevelopment to lower contrast; underexposure/overdevelopment to increase contrast... Special and hotter soup if you must push [essentially underexposure but adding back some chemical fog in prolonged or hotter processing].

Colour film processing is more restrictive, both in time and temperature, we cannot do much.

Before there was light meter, we use the sunny 16 rule [only applicable in daylight] to start...but for any geographic location and any date, ever wonder why?

Later, we have light meters. We set them according to what the film box says or what we had experience in...whether the meter is hand held, built into the camera, or automatic [in exposure cut off...in time or aperture].

The light meter does not and cannot know if you lied.

Digital is no different. There is a native ISO. Many camera makers mark it as a somewhat pessimistic ISO 200, so that users have less chance to blow out the high light...and let the shadows fall as they may [within the bit depth in the tail end, just like transparency films]. Post-processing can boost the shadow details if you choose, but not much beyond 3 or 4 stops or electronic noise will become visible.

Auto-levelling is the generic term. You can of course print from the DNG files straight...if your exposures were correct.

In using this back-to-basics digital back, first learn the basics…didn’t all Leica aficionados? ;)
 
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Pickett Wilson said:
So, when do we see the prototype?
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I am waiting firstly for the suggestions and criticisms to die down, especially from the Leica experts.

Then it is incorporation and paper work...take about a week.

Then offering of shares to those who have expertise/time or simply money [except Leica or its agents, I do know a little about corporate laws and German or Swiss tactics]...I have a proven fair formula, but others may disagree.

Some capitalization must happen to buy stuff, make prototypes, alfa/beta testing and hold meetings...or if I fund the whole works, I own most of the company...except portions traded for expert time.

Before I can convince time or money investors, I must do a little formal market research...due diligence if only for myself.

AND, Solms after consulting with Heerbrugg, might want to buy us out before we start. In that case, happy retirement for the investors [only]. :D
 
Frankie, so you are saying that the plan is to just rely on the latitude of the sensor and fix the exposure in post? That doesn't seem like the path to optimum image quality. And why would you want to compromise image quality just to get some kind of digital image from an old Leica? A $500 Canon XTi has far fewer compromises.

I own and shoot Leicas, and I just can't get my head around why someone would want something with these kind of minimal specs.
 
reklats said:
That's basically what you're doing in every digital camera anyway; can't really change the quantum efficiency or storage capacity of the sensor.

[edit/addition]
@Brian: Shouldn't that be mostly from the removal of the colour filter, since with that you're throwing away two thirds of (white) light at every photo site? A good IR-filter doesn't block more than some percent, at most, of the visible range. Might worsen the situation further at the edges though I guess.
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The IR filter blocks half of the spectral response of a Silicon Sensor. When you remove it, you pick up a full-stop. You are getting all the light out to 11,000A.
 
The Shutter mechanism controls the exposure of the CCD. The trick is when to start the integration times. "IF" I were doing this -and I am not- an interface controller using a photodiode at the film gate would be able to sense and measure the shutter speed in realtime. Probably an embedded microcontroller such as a PIC16F716 could handle the photodiode, realtime shutter-speed measurement, and signal the main CPU for start/stop time of the Sensor integration.

http://www.microchip.com/wwwproducts/Devices.aspx?dDocName=en010216

Not that i know anything about this stuff.
 
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