[Leica] not sure - but here goes

[mark at rabinergroup.com (Mark Rabiner)]

Thanks Frank!

--------------------
Mark William Rabiner
Photography
mark at rabinergroup.com


> From: Frank Dernie <Frank.Dernie at btinternet.com>
> Reply-To: Leica Users Group <lug at leica-users.org>
> Date: Sat, 11 Sep 2010 09:25:21 +0100
> To: Leica Users Group <lug at leica-users.org>
> Subject: Re: [Leica] not sure - but here goes
> 
> Hi Mark,
> on the off chance your question is not rhetorical here are a few reasons 
> for
> the difference in price between small and large sensors being much bigger 
> than
> thet between 35mm and 120 film.
> Firstly the film is the same stuff, just a different shaped layer of 
> plastic
> coated with the same light sensitive stuff.
> In the case of sensors they are made on a wafer of silicone. The crystal
> structure of the silicone wafer has imperfections on it, and any chip 
> etched
> onto a part of the silicone wafer with an imperfection won't work, so it is
> scrap. If, for example there is a defect every 2 inches, -all- 2 inch or
> bigger chips will be scrap, so that is the biggest sensor which can be made
> will be less than 2". Depending on how the layout of random faults and the
> sensor layout fall on a wafer, there will be a high scrap rate even on 
> sensors
> less than 2". The scrap rate only comes down to negligible when the sensors
> are -very- much less than 2".
> This means big sensors are expensive since very few few of those produced
> work. They are also expensive since the economy of scale is not there. Some
> are made by joining 2 smaller sensors together with software to "fix" the
> image at the join...
> The technology for making the wafers is developing, so prices will come 
> down
> eventually, but never to the film ratio.
> 
> Luckily, the sensor design of small and big chips is -not- the same, unlike
> film. With film, going larger format increases the potential quality by the
> increase in film area less the reduction in lens quality due to the larger
> image circle. Going smaller with digital the loss is -much- less than with
> film since the smaller sensors are -much- finer resolution than large 
> sensors
> so the loss of quality is not nearly as much as it used to be with film.
> cheers,
> Frank
> 
> On 11 Sep, 2010, at 07:12, Mark Rabiner wrote:
> 
>> Brownie film does not cost that much more than 35mm film. Why should
>> digital? Well it does. Bummer.
> 
> 
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