[MF3D.FORUM:628] Re: Thanks Paul

["Bill Glickman" <bglick@xxxxxxxx>]

Don

       I follow your logic completely and agree on most items you mention.
With 3d, it seems their needs to be a balance with everything in focus vs.
no blur from movement, so this is where shooting at f32 - 45 can be painful
in my eyes.  And yes you are right, at f32, you are limiting your self to a
max. of 33 lpmm... divide that by 4x for the viewer lenses and you are at 8
lpmm, which is still greater than the 5 lpmm good human vision can resolve.

But what I was mainly referring to was a deciding on a versatile lens, one
that can shoot at 5.6 if you are shooting waves crashing on rocks...(achieve
stop motion) in which case many LF lenses would produce very poor
results.... and this is due to their very poor MTF curves at these wide apt.
So bad it would be noticeable in the viewer when shot wide open..   MF
glass, has excellent sharpness over almost the entire f stop range, usually
tailing downwards at the smallest openings.   But in still situations, I
totally agree, stop all the way down, you are not enlarging enough to allow
diffraction to rear its ugly head!

Regards
Bill G

----- Original Message -----
From: "don lopp" <dlopp@xxxxxxxxxxxxxxx>
To: "Medium Format 3D Photography" <MF3D.Forum@xxxxxxxxxxxxx>
Sent: Wednesday, May 31, 2000 11:10 PM
Subject: [MF3D.FORUM:627] Re: Thanks Paul


> As reguards MTF I dont believe that any of my lenses used for stereo have
> MTF betterthan 50 but they make decent stereo images . The lenses on my
> Rolledoscope probably have an MTF less than 30 but they look O K in my
> opinion. I beleive that sharpness is more important to me than a high MTF.
> >From my limitted experience color film is so fuzzy { low lines per mm
> resolved }that depth of focus is my main opticle goal  Ihave an obsession
to
> get everything  in focus which usually means shooting at f 22.0,  f 32.0
or
> even at f 45.0 at which point most lenses have a low MTF score. I do not
> have any way of measuring MTF so I have to trust the manufacturers.
> Accordingly the Hasselblad 100mm is far better than their 80 mm lens but I
> do not see many in use. I qwestion the importance of MTF because of my use
> of small apperatures where diffraction wipes out high MTF numbers. Also,
the
> low power lenses used in most viewers are not capable of  showing  the
> differences between good and very good lenses in my opinion{4 power
lenses_I
> usuall use a 25 power glass to check my transparencies } Incidentally I
have
> used 45mm, 47mm, 50mm.65mm,75mm, 80mm.,100mm.,150mm., and 180mm.,lenses
for
> M.F. stereo with the 150 and 180mm lenses being a bit difficult to use
> because of their shallow depth of focus.  Don
> ----- Original Message -----
> From: "Bill Glickman" <bglick@xxxxxxxx>
> To: "Medium Format 3D Photography" <MF3D.Forum@xxxxxxxxxxxxx>
> Sent: Tuesday, May 30, 2000 11:36 PM
> Subject: [MF3D.FORUM:625] Re: Thanks Paul
>
>
> > Don
> >
> > You wrote:
> >
> > > I am at a lossas to what MTF has to do with medium format stereo.  Don
> >
> >       The MTF curve of a lens, (given by the manufacturer) shows the
> > apertures that will produce the greatest contrast and resolution for
that
> > lens.  If you use LF lenses and try to shoot at f8, you will usually get
> > poor results vs. shooting at f22.  The reason is, all LF lenses are
> designed
> > with their sweet spots at f16, f22 and f32, while the wide apertures are
> > made strictly to view the ground glass.   LF lenses are made for studio
> and
> > landscapes primarily, not fashion and weddings like MF lenses are
designed
> > around.
> >
> >        MF glass is optimized at wider apt., say 4.0 to 11 or sometimes
> even
> > 16.   Therefore you can shoot at faster shutter speeds to prevent blur
and
> > produce the best images that lens can produce.   So it seems sensible to
> me,
> > that MF lenses are the "ideal" stereo lenses to use.  Of course, if one
> > wants to shoot 35mm,  mostly all 35mm glass is optimized at the wider
> > apertures.
> >
> >       Of course, DOF limits still need to be respected regardless of the
> > type of lens being used.  But considering slight blurs area so
exaggerated
> > looking through a viewer vs. a print, a few extra stops can make a huge
> > difference!
> >
> > Regards
> > Bill G
> >
> >
> >
> > > ----- Original Message -----
> > > From: "Bill Glickman" <bglick@xxxxxxxx>
> > > To: "Medium Format 3D Photography" <MF3D.Forum@xxxxxxxxxxxxx>
> > > Sent: Monday, May 29, 2000 10:07 PM
> > > Subject: [MF3D.FORUM:613] Re: Thanks Paul
> > >
> > >
> > > > Stuart
> > > >
> > > > You wrote:
> > > >
> > > > > By the way kevin,  I really hope you consider DUAL cameras as you
> will
> > > > have
> > > > > even more enjoyable results if the two images are snapped at the
> same
> > > > time.
> > > > > The little differences that pop up (literally) when using a slide
> bar
> > > can
> > > > > ruin an otherwise good picture.  The mind instantly recognizes
> > > > imperfections
> > > > > like a leaf out of position, a flag furled differently, etc...
> > > >
> > > >          I have been contemplating this exact issue.  Maybe you can
> > offer
> > > me
> > > > some insight.  I have two M7's now, and my missing link is the
> inability
> > > to
> > > > snap both shots at once when the camera spacing needs to be 65mm.
> (Due
> > to
> > > > the cameras inability to get this close)  I was wondering when
> shooting
> > > > landscapes shots, how critical this is... From what you write above,
> it
> > > > sounds like even the slightest leaf or branch being out of place
will
> > play
> > > > havoc with ones ability to fuse subjects.  I kind of suspected this,
> but
> > > > have no base for comparison, since I never had the ability to try
this
> > > both
> > > > ways.   Do you find that snapping both shots at once is critical
some
> of
> > > the
> > > > time, most of time or almost all the time?  Thats what I am trying
to
> > get
> > > > the feel for....  Any input in this area would be very helpful...
> > > >
> > > > I can probably guess this dual firing is very critical.... if so,
what
> > are
> > > > some recommendations on newer MF camers that can acheive the
critical
> > 65mm
> > > > spacing, can be fired siumltaneously and also offer interchangeable
> > > lenses?
> > > > It seems most of the new box type cameras by Mamiya, Hassy, Rollei,
> > > Bronica,
> > > > etc. are way to big,  preventing the desired 65mm spacing.
> > > >
> > > > If I were to mount my two M7 80mm lenses on a view camera lens
board,
> > they
> > > > still will not be 65mm apart, but can get to about 70mm.  Will this
> > extra
> > > > 5mm spacing ruin the desired effect?  Or would it go un noticed as
> long
> > as
> > > I
> > > > am not shooting very close objects, like 3ft.   If this is feasible,
I
> > > would
> > > > consider putting 2 M7 mounts in a Toyo lens board,  focus via the
> ground
> > > > glass, and then insert a 6x12 roll film holder (with a slight bit of
> > > > modification) and get two 6x6 chromes.  Of course I would need a
light
> > > > divider inside the bellows.  I can link the shutters electronically.
> > > > I have considered using LF lenses, but they will not get much
closer,
> > and
> > > > they do not seem as ideal as MF glass since the MTF curves on LF
> lenses
> > > are
> > > > not optimized until f16 and higher, while  MF glass is optimized at
> the
> > > > wider and faster apertures... and speed seems a great advantage in
MF
> > 3d.
> > > >
> > > > Any holes in my thinking?
> > > >
> > > > Regards
> > > > Bill G
> > > >
> > > >
> > >
> >
>