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Re: [OM] Digital and the 100/2 - Lenses, not Lipitor

Subject: Re: [OM] Digital and the 100/2 - Lenses, not Lipitor
From: "Carlos J. Santisteban" <zuiko21@xxxxxxxxx>
Date: Fri, 14 Oct 2011 12:31:12 +0200
Hi Ken and all,


  From: Ken Norton <ken@xxxxxxxxxxx>
>What I didn't mention was that this third attempt at getting the shot
>without getting a dreaded hotspot in the middle portion of the picture.
This
>is something we've seen a small handful of lenses do with digital sensors,


Add Voigtländer's Nokton 50/1.1 to that list... but only on the IR region!
CV coatings are really effective within the visible spectrum, but become
ineffective at other wavelengths -- as expected. You already know of my use
of the M8 as an IR camera, and due to the *severe* light loss, that fast
Nokton would be the logical choice. But beyond f/2.8 or so, the dreaded
hotspot becomes visible... Not that shallower apertures are usual in my IR
shooting, but worth noting anyway.

On the other hand, when shooting visible wavelengths, no problems happen...
but you better keep that UV-IR cut filter on! <
http://www.flickr.com/photos/zuiko21/6208175582/in/photostream>. With other
CV lenses (e.g. Skopar 21/4) neglecting the use of the UV-IR cut shows
impaired flare resistance, compared to the usual high performance in this
regard.


>The film version of the shots were no problem--only the digital.


Another logical consequence: film is a dark matte surface, instead of the
mirror-like appearance of the sensor. Think about (the much mourned) TTL-OTF
metering, even with flash...


>I haven't seen this with other shots, but when shooting into the bright
>sunset it showed up when the aperture was closed down quite a bit. Opening
>it up made the hotspot disappear.


In fact, it just spreads all over the image, causing a slight decrease in
contrast. Not necessarily a bad thing, since it may open the shadows a bit.
Back to CV lenses, some people were willing to pay extra for the
_single-coated_ versions of the 35/1.4 and 40/1.4...


Cheers,
-- 
Carlos J. Santisteban Salinas
IES Turaniana (Roquetas de Mar, Almeria)
<http://cjss.sytes.net/>
-- 
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