Archived posting to the Leica Users Group, 2015/11/04

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Subject: [Leica] The SL
From: mark at (Mark Rabiner)
Date: Thu, 05 Nov 2015 01:07:40 -0500

I agree the stop down  DOF preview thing is only good for the Bonneville
Salt Flats at high noon. Other than that you cant  make out much.  y0u scan
see if secular highlights seem sharp. I was fond of DOF scales on lenses
when they made them on Nikons and Canons but I think on Leicas they are
still there.
But I'm unfamiallwir with these new fangle3d electronic viewfinders to I
thought they are like "Predator".

On 11/4/15 10:22 PM, "Geoff Hopkinson" <hopsternew at> wrote:

> Yep didn't forget that. I was attempting to explain that if the lens was
> already at the shooting aperture (like an M lens for example) it may be
> that an EVF can still display a bright enough image for focussing (that is
> your EVF brightness is controllable).
> Focus at the shooting aperture of course defeats any focus shift (for
> example from f/1.4 to f/4). Much depends on what you are shooting I 
> imagine.
> Just played with this on the XT1 and the Summilux 50 ASPH down to f/8.
> However personally I have never found DoF preview sufficiently precise or
> particularly useful in any camera at all from the 70's forward. I may be an
> outlier there ;-)
>  ---------- Forwarded message ----------
> From: Frank Filippone <red735i at>
> To: "'Leica Users Group'" <lug at>
> Cc:
> Date: Tue, 03 Nov 2015 22:35:51 -0800
> Subject: r
> Yes, all true.....but you forget that DOF is, for example at F8, greater
> than at F2.  So focusing is much less precise without auto stop
> down..........
> Frank Filippone
> Red735i at
> 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.
>> 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.
> Cheers
> Geoff
> _______________________________________________
> Leica Users Group.
> See for more information

Mark William Rabiner

In reply to: Message from hopsternew at (Geoff Hopkinson) ([Leica] The SL)