Drowning men - was Re: [Leica] Surprises at Photokina

[hoppyman at bigpond.net.au (Geoff Hopkinson)]

Frank, I understand what you are trying to express. But ;-) the M8 'crop
factor' is 1.33 and the 21 on an M8 does not have the same angle of view as
a 24 on an M6. Did you mean the nearest comparable prime wide in the Leica M
range?
To emulate that 24 on an M6 you need an 18mm on the M8 (right now only the
excellent but slower f4 Zeiss model available) not a 21mm. Trust me, I'm a
user ;-)

Calculating your examples using 2 metres distance for person and background
you really have to compare at the same aperture for it to be meaningful; 
 M6 24mm 2.8 - 1.27m DoF (4 feet 2 inches).
 M8 21mm 2.8 exactly the same (but the AoV is not).
 M6 24mm 1.4 59cm or 23 inches.
 M8 21mm 1.4 exactly the same. 
My main point is that I don't think that narrow DoF is a primary concern
with these wides since they all have a lot (which I think is a great
characteristic). 
Cheers
Geoff
http://www.pbase.com/hoppyman/e
http://gallery.leica-users.org/v/gh/

-----Original Message-----
Subject: RE: Drowning men - was Re: [Leica] Surprises at Photokina

I made my point awkwardly.... I was comparing the wide open performance DOF
between the 21 F1.4 on the M8 to the 24 F  2.8 ASPH on the M6.   Closest
Angle of view (AOV), same DOF.  The point was that the wide open 21 Lux
offers no more DOF on an M8 than the curent ( or past) wide open 24 Elmarit
on film.

Mark Rabiner had made the statement that he wanted more isolation of the
chief subject using the 21 Lux....and an M8... wide open.  He won;t get it
relative to an M6 and the 24 Elmarit.

I always get the efective multiplier ratio of he M8 wrong.. it is 1.5.  So
the 21 on the M8 has the same AOV as a 31 ( 28?) on the M6.  So the
comparison that is fairer is the 28 Elmarit  to the 21 Lux.  However, while
I was wrong about the lenses invloved, the argunment still holds.... 

The M8 requires a wider FL lens to perform the same AOV as a longer lens on
the M6.  Because the M8 lens is of smaller Fl, it has more DOF than a longer
lens on the M6.  The issue of subject isolation, by use of wide open
imagery, is better done by a longer lens of faster speed.  thus an M6 make a
better isolation tool than an M8 for any given AOV.

Note:   There is no comment here at all about optical performance.   It only
has to do with DOF and Fl and AOV.

Frank

>Frank what are you trying to say there on angle of view?
>To approximate the field of view of a 24mm on an M6 you need an 18mm on the
>M8 models.
>http://www.pbase.com/hoppyman/image/101813580
>Most fellow M8 users that I have spoken to M8 aren't bothered by the 'crop
>factor'. On DoF, an on-line calculator (at 2 metres) confirms what you
said.
>But that's an apples and oranges thing. 
>My view is that performance wide open (and that's 2 extra stops) is much
>more important than DoF when it comes to wides.  Obviously inherently they
>have a LOT. Bless their versatile hyper focal hearts. 
>
>Cheers
>Geoff
>http://www.pbase.com/hoppyman/e
>http://gallery.leica-users.org/v/gh/
>
>-----Original Message-----
>From: lug-bounces+hoppyman=bigpond.net.au@leica-users.org
>[mailto:lug-bounces+hoppyman=bigpond.net.au@leica-users.org] On Behalf Of
>red735i@earthlink.net
>Sent: Monday, 15 September 2008 12:28
>To: Leica Users Group
>Subject: Re: Drowning men - was Re: [Leica] Surprises at Photokina
>
>Mark.. a 21 lens at F1.4 would have much the same DOF as a 24 at F2.8 ( I
do
>not have the DOF tables handy, but it sounds about right....)
>
>The problem with the M8 is that to get a 24mm Angle of view on a 35 full
>frame, a 21 lens must be used with the M8... so you never get more DOF
>isolation than you would with film on a M6 and a 24mm lens.
>
>The M9 had better be full frame....
>
>Frank
>
>
>
>
>_______________________________________________
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_______________________________________________
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