Archived posting to the Leica Users Group, 2010/03/26

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Subject: [Leica] OT: Another maybe not so stupid GH1 question
From: passaro.vince at gmail.com (Vince Passaro)
Date: Fri, 26 Mar 2010 10:09:22 -0400
References: <daaeb97e1003251901x39685bb5w60bb366bf9ca4089@mail.gmail.com> <daaeb97e1003252014q462910c5yefac14166cf0ae48@mail.gmail.com> <a3f189161003252054y79906939o1a220e432c04a26c@mail.gmail.com> <19b6d42d1003252129t4f187030h3c55760ac01e99b@mail.gmail.com> <eb6799211003252204n6fb843fblb96565e0931ad77a@mail.gmail.com> <19b6d42d1003260030r45049a51rd16732edcf098182@mail.gmail.com> <eb6799211003260055o19325a60jb7267d251309394b@mail.gmail.com> <19b6d42d1003260113g15b3a95bx4e1cf0a2b4cac69e@mail.gmail.com> <eb6799211003260122x1a2b504bsccd54a7b2f51fd09@mail.gmail.com> <36172e5a1003260616h45407e17l2564675b4f14c938@mail.gmail.com>

It's interesting to study the differences in these (pondering the exact
coordinates of "about the same distance"). (I realize this is really basic
stuff to most of you so -- skip. I'm just trying to figure it out in a way I
can internalize and never have to think about again, as with, say, making a
left turn in a 5-speed manual transmission car as I do every day) -- but the
main difference appears to be in the angle of the lines leading to Dr. Man's
Vanishing Point (a drive-in theater B-film Roger Corman title if ever there
was one). With the ones on the 20 starting somewhere behind us and
*much*farther apart then they would with a 40mm on a 35mm frame. The
ones in the
M9 50mm seem almost straight and parallel though the whole image and a 40mm
on the M9 would only be a little less parallel than that.

To my extremely amateur and unpracticed eye the image of Geoff looks roughly
like what I'd get with my 28mm f/2.8 AIs on my old Nikon FE if I held the
camera about a foot-and-a-half or a foot closer to Geoff than Howard likely
did here. Or a 35mm held a bit further back than that, maybe eight inches or
twelve.

So for me, I'm starting to picture the crop not as snipping the edges away
from a two-dimensional photographic print (and then possibly blowing it up a
little or a lot -- this is how many publications and people basically
describe it); NOR is it a doubling of the size of everything in the len's
view (absolutely not that, in fact; even though this is implied quite
often); but I'm picturing the 20mm image on the 2X sensor as a
three-dimensional rectilinear cone -- a four-cornered dunce cap pointed
toward the center/rear of the image -- with the some of the wider end of it
sawed off so it "begins" closer to the focal point than it would as a
regular 20mm full frame image; the same effect roughly achieved with a 20mm
full frame held a little closer to the image (but not half the distance
closer: no, less than that).

Sorry. But thanks for those images Geoff.

Vince

On Fri, Mar 26, 2010 at 9:16 AM, Geoff Hopkinson <hopsternew at 
gmail.com>wrote:

> Howard grabbed this shot over dinner recently, no doubt intent on showing
> me
> consuming dessert.
> The next shot is with my 50 on the M9 (pointing across the table the other
> way but about the same distance).
> http://gallery.leica-users.org/v/hoppyman/1/P1010223.jpg.html
>
>
>
> Cheers
> Geoff
> http://www.pbase.com/hoppyman
>
>
> On 26 March 2010 18:22, Richard Man <richard at imagecraft.com> wrote:
>
> > DoF I meant as Depth of Field (Death of Field?), i.e. the amount of
> > "in-focus" zone, which is related to the focal length, distance to
> subject,
> > distance of viewing, and size of print, and of course, the circle of
> > massive
> > confusion.
> >
> > On Fri, Mar 26, 2010 at 1:13 AM, Vince Passaro <passaro.vince at 
> > gmail.com
> > >wrote:
> >
> > > That's what I thought you meant. But ain't that DofF?
> > >
> > > I'm going to make a pronouncement now: nobody really understands this
> > crop
> > > factor thing in a rational way: some of us (not I, but others, among
> you
> > > guys) know from practice how a 35mm lens will look on a full frame M9
> > > versus
> > > a 1.3 M8 versus a 1.5 Nikon versus a 2X G series, but no one can
> explain
> > > it.  The fabulous and popular new 20/1.7 for all you G-sters is a good
> > > starting point. I look up and see new postings from the lens every day.
> > And
> > > the images don't look like 20mm images and they don't look like 40mm
> > images
> > > either, except when they've been cropped even further on PS or LR.
> > >
> > > On Fri, Mar 26, 2010 at 3:55 AM, Richard Man <richard at 
> > > imagecraft.com>
> >  > wrote:
> > >
> > > > Perspective as in .... the vanishing point!!
> > > >
> > > > e.g. if you take a photo of a person with a building way behind them.
> > On
> > > a
> > > > 40mm perspective, the building will appear one size, but a 20mm
> > > perspective
> > > > will (I'm pretty sure) make the building look smaller.
> > > >
> > > >
> > > > On Fri, Mar 26, 2010 at 12:30 AM, Vince Passaro <
> > passaro.vince at gmail.com
> > > > >wrote:
> > > >
> > > > > Richard: I understand "closeness" and "frame" and DofF here, but I
> > > don't
> > > > > know what you mean by "perspective" in this case. Can you explain
> the
> > > > > perspective part?
> > > > >
> > > > > On Fri, Mar 26, 2010 at 1:04 AM, Richard Man <
> richard at imagecraft.com
> > >
> > > > > wrote:
> > > > >
> > > > > > Vince, try this:
> > > > > >
> > > > > > You are getting a ~40mm closeness, e.g. if you want to frame a
> > > > headshot,
> > > > > > you
> > > > > > will end up ~where you would be if you are using a 40mm lens on a
> > > 35mm
> > > > > > camera, but the perspective (and DoF) would still be 20mm. Hence
> > the
> > > > look
> > > > > > is
> > > > > > not quite like straight 40mm on a 35mm camera.
> > > > > >
> > > > > >
> > > > >
> > > > > _______________________________________________
> > > > > Leica Users Group.
> > > > > See http://leica-users.org/mailman/listinfo/lug for more
> information
> > > > >
> > > >
> > > >
> > > >
> > > > --
> > > > // richard <http://www.imagecraft.com/> blog: <
> > > > http://imagecraft.wordpress.com>
> > > > // portfolio: <http://www.imagecraft.com/pub/PICS/AnotherCalifornia2
> >
> > > > // mailing lists: <http://www.imagecraft.com/contact.html>
> > > > [ For technical support on ImageCraft products, please include all
> > > previous
> > > > replies in your msgs. ]
> > > >
> > > > _______________________________________________
> > > > Leica Users Group.
> > > > See http://leica-users.org/mailman/listinfo/lug for more information
> > > >
> > >
> > > _______________________________________________
> > > Leica Users Group.
> > > See http://leica-users.org/mailman/listinfo/lug for more information
> > >
> >
> >
> >
> > --
> > // richard <http://www.imagecraft.com/> blog: <
> > http://imagecraft.wordpress.com>
> > // portfolio: <http://www.imagecraft.com/pub/PICS/AnotherCalifornia2>
> > // mailing lists: <http://www.imagecraft.com/contact.html>
> > [ For technical support on ImageCraft products, please include all
> previous
> > replies in your msgs. ]
> >
> > _______________________________________________
> > Leica Users Group.
> > See http://leica-users.org/mailman/listinfo/lug for more information
> >
>
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information
>


In reply to: Message from digiratidoc at gmail.com (James Laird) ([Leica] OT: Another maybe not so stupid GH1 question)
Message from digiratidoc at gmail.com (James Laird) ([Leica] OT: Another maybe not so stupid GH1 question)
Message from sonc.hegr at gmail.com (Sonny Carter) ([Leica] OT: Another maybe not so stupid GH1 question)
Message from passaro.vince at gmail.com (Vince Passaro) ([Leica] OT: Another maybe not so stupid GH1 question)
Message from richard at imagecraft.com (Richard Man) ([Leica] OT: Another maybe not so stupid GH1 question)
Message from passaro.vince at gmail.com (Vince Passaro) ([Leica] OT: Another maybe not so stupid GH1 question)
Message from richard at imagecraft.com (Richard Man) ([Leica] OT: Another maybe not so stupid GH1 question)
Message from passaro.vince at gmail.com (Vince Passaro) ([Leica] OT: Another maybe not so stupid GH1 question)
Message from richard at imagecraft.com (Richard Man) ([Leica] OT: Another maybe not so stupid GH1 question)
Message from hopsternew at gmail.com (Geoff Hopkinson) ([Leica] OT: Another maybe not so stupid GH1 question)