Archived posting to the Leica Users Group, 2004/10/05

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Subject: [Leica] Re: RE: Re: Photokina _ The lens on Tom's RD1
From: jcb at visualimpressions.com (JCB)
Date: Tue Oct 5 18:09:37 2004
References: <BD88818D.AF82%s.dimitrov@charter.net> <BAY19-DAV2JXrRjbDt300066e39@hotmail.com>

At 05:29 PM 10/5/2004, eric wrote:


>Nope - I took a look this evening into the lens of my konica KD-500Z.
>Definitely a shutter closing and opening.


As I said, some have real shutters. but they do not determine the actual 
exposure. They open and get out of the way, the substrate is pulsed (there 
MUST be a substrate pulse in order to actually make the sensor collect the 
light. The length of the pulse determines the window in which the light is 
collected.

There are some odd ball set-ups that pulse the substrate on, use a real 
shutter to plop the light onto the sensor, and then drop the substrate 
pulse when the real shutter closes. These can work OK as long as the sensor 
is the kind that can tolerate a long substrate pulse, longer than the 
shutter speed. You'll find lots of low and intermediate P&S cameras with 
the inability to take long exposures. Mainly because the cheap sensors have 
a max pulse width, which amounts to around 1/30th second. These cameras 
cannot take silky waterfall pictures.

There are lots of goofy combinations in order to get around patents. Bottom 
line, a sensor exposure is via a substrate pulse. Everything else is 
ancillary.

JB 


In reply to: Message from s.dimitrov at charter.net (Slobodan Dimitrov) ([Leica] RE: Re: Photokina _ The lens on Tom's RD1)
Message from leica_korenman at hotmail.com (eric) ([Leica] RE: Re: Photokina _ The lens on Tom's RD1)