Archived posting to the Leica Users Group, 2015/11/03

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Subject: [Leica] The SL
From: mark at (Mark Rabiner)
Date: Tue, 03 Nov 2015 22:15:43 -0500

Shouldn't you be using your lenses fully wide open all the time to fully
take advantage of the inimitable  Leica glow and bokeh of your premium Leica
glass? That's what all the pros do I promise. Wide open all the time.  No
stopping down for nothing. Otherwise you get distracting backgrounds which
might indicate where the picture was taken.

On 11/3/15 9:47 PM, "Doug Herr" <wildlightphoto at> wrote:

> My desire for automatic aperture is to combine the maximum aperture's rapid
> fall-off of optimum focus with the smaller working aperture's greater DOF,
> without having to turn a ring or push a button or repeat a Barnackian 
> chant to
> cause the lens to stop down.
> Doug Herr
> Birdman of Sacramento
> -----Original Message-----
>> From: Geoff Hopkinson <hopsternew at>
>> Sent: Nov 3, 2015 6:38 PM
>> To: Leica Users Group <lug at>
>> Subject: Re: [Leica] The SL
>> Do I have it right that the desire for automatic diaphragm control is for
>> focus at maximum aperture then stopping down to shooting aperture at the
>> moment of exposure?
>> Doesn't the use of the EVF potentially permit the finder brightness to be
>> controlled? If the lens is stopped down (ie not operating with auto
>> diaphragm) of cause the image arriving at the sensor is what is used for
>> focussing. So the desire for auto diaphragm control comes from the OVF
>> systems?
>> M lenses of course are already being employed with the initial SL units in
>> the field.
>> Happy to be educated.
>> ---------- Forwarded message ----------
>> From: Doug Herr <wildlightphoto at>
>> To: Leica Users Group <lug at>
>> Cc:
>> Date: Tue, 3 Nov 2015 01:14:25 -0800 (GMT-08:00)
>> Subject: Re: [Leica] The SL
>> Richard Man wrote:
>>> You can get autoexposure only if the camera knows what the open aperture
>>> and the taking aperture are. If the lens does not generate those info, 
>>> then
>>> some kind of manual system is needed
>> Autoexposure with TTL metering in apertured-preferred mode is simple with
>> no auto-diaphragm, no data other than light, ISO and shutter speed is
>> needed.
>> With TTL metering and an automatic diaphragm the camera needs to know the
>> difference between open aperture and working aperture.  It does not need 
>> to
>> know what the actual open aperture is or the actual working aperture, only
>> the difference.  Any other data is extra and can be used for the user's
>> convenience, but is not required for autoexposure function.
>> Doug Herr
>> Birdman of Sacramento
>> Cheers
>> Geoff
>> _______________________________________________
>> Leica Users Group.
>> See for more information
> _______________________________________________
> Leica Users Group.
> See for more information

Mark William Rabiner

In reply to: Message from wildlightphoto at (Doug Herr) ([Leica] The SL)