On 14 Feb 2005 at 15:03, Keith Davison wrote:
> > Perhaps someone familiar with both these chips, in design- and
> > manufacture-context, can shed a light on this?
> > (with the most important question being whether one could order a new 1Ds
> > without the filter, straight from the factory (like can/could be done with
> > some aftermarket digibacks for medium format; no IR-block, no
> > anti-aliasing)
>
> Or you could just order an EOS 20Da from Canon, which is specially
> produced with the IR block filter omitted. It also has a partially
> transmissive mirror which allows real-time focusing on the LCD screen and
> other optimisations for IR.
>
> Japan only at the moment, but we can keep our fingers crossed.
>
> http://www.dpreview.com/news/0502/05021405canoneos20da.asp
>
> I want one!
>
> Keith Davison
I wonder if this semi-pellicle mirror [*] has the opposite ratio of
reflection/transmission as the 1n-RS & old RT....that one was 33/66,
but needed a light-optimized viewfinder/focus-screen to compensate
the one-stop light loss[**], which had a slight disadvantage for
focusing by hand....
[*] still functioning as swing-up before/during exposure?
[**] ordinary mirrors are not 100/0 either, but 66/33, allowing light
past the primary mirror, onto the secondary mirror, and down to the
AF-sensors on the floor of the mirror box.....and the difference
between the 33 in the above alinea and the latter 66 is exactly 1
stop....:))
--
Bye,
Willem-Jan Markerink
The desire to understand
is sometimes far less intelligent than
the inability to understand
<[EMAIL PROTECTED]>
[note: 'a-one' & 'en-el'!]
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