Archived posting to the Leica Users Group, 2010/09/11

[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]

Subject: [Leica] not sure - but here goes
From: frank.dernie at btinternet.com (FRANK DERNIE)
Date: Sat, 11 Sep 2010 03:02:35 -0700 (PDT)
References: <C8B09604.32B4%mark@rabinergroup.com> <8199DF19-732E-4893-8E0B-4FACA96A8DBD@btinternet.com> <AANLkTi=_N4YPCcBtSWyWvT4q0vTnoAt0k5LaJfEHe3TY@mail.gmail.com>

More crap spelling than wandering mind I fear...


----- Original Message ----
From: "piers at hemy.org" <piers.hemy at gmail.com>
To: Leica Users Group <lug at leica-users.org>
Sent: Saturday, 11 September, 2010 9:37:52
Subject: Re: [Leica] not sure - but here goes

Spot on, Frank, of course. But you mean silicon - perhaps your mind
was wandering?

On 9/11/10, Frank Dernie <Frank.Dernie at btinternet.com> wrote:
> 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.
>
>
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information
>

_______________________________________________
Leica Users Group.
See http://leica-users.org/mailman/listinfo/lug for more information



Replies: Reply from hopsternew at gmail.com (Geoff Hopkinson) ([Leica] not sure - but here goes)
In reply to: Message from mark at rabinergroup.com (Mark Rabiner) ([Leica] not sure - but here goes)
Message from Frank.Dernie at btinternet.com (Frank Dernie) ([Leica] not sure - but here goes)
Message from piers.hemy at gmail.com (piers@hemy.org) ([Leica] not sure - but here goes)