Archived posting to the Leica Users Group, 2011/04/28
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]thx ric On Apr 28, 2011, at 6:38 PM, Larry Bullis wrote: > A pinhole really doesn't have a "focal length"; the location of the > pinhole establishes the perspective. There can be no formula for > determination of the size of the image circle that covers everybody > because all pinholes are not the same. The typical drilled ones (laser, > mechanical, makes no difference) are actually small tubes, which limits > their coverage. The best pinholes are made in extremely thin material and > have knife-sharp edges, or the closest approximation to that possible. > > The various sites that George mentions will give you formulae for the size > of the hole needed, but it might be important to note that each formula is > predicated upon certain assumptions. These include the tradeoff between > resolution and diffraction, and the particular wavelength that one accepts > as a standard. Generally, the wavelength is assumed to be in the green > range. As for resolution/diffraction, unless you want something unusual, > like enhanced diffraction colors, a published formula ought to work fine > for you. > > Now, MAKING the hole to spec - that's another issue! If you buy one, you > get a tube. > >> Date: Wed, 27 Apr 2011 20:26:54 -0700 >> From: Richard Man <richard at imagecraft.com> >> Subject: Re: [Leica] Digital Pinhole for Micro 4/3 >> To: Leica Users Group <lug at leica-users.org> >> Message-ID: <BANLkTikApUO4=AwX4Ww0pHCDNzsvzGcsdQ at mail.gmail.com> >> Content-Type: text/plain; charset=ISO-8859-1 >> >> How does one calculate the effective length of a pinhole? Is the "body >> cap" >> distance the "normal" distance for most format? e.g. 50mm for SLR? And how >> is the size of image circle calculated? >> >> On Wed, Apr 27, 2011 at 8:10 PM, Jayanand Govindaraj <jayanand at >> gmail.com>wrote: >> >>> > Ken, >>> > Nice shots. I was also thinking of buying this - it is inexpensive >>> > enough >>> > for an experiment! >>> > Cheers >>> > Jayanand >>> > >>> > On Thu, Apr 28, 2011 at 5:19 AM, Ken Carney <kcarney1 at cox.net> >>> > wrote: >>> > >>>> > > Jayanand, >>>> > > >>>> > > Thanks for posting, I may give this one a try. I like pinhole, but >>>> > > only >>>> > > wide angle pinhole. My favorite pinhole camera is a Leonardo 4x5" >>>> > > with >>> > a >>>> > > 1.5" focal length, which is roughly 15mm in 35mm terms. I have an >>>> > > 8x10" >>>> > > pinhole with the same approximate equivalent. 22mm is not as good >>>> > > as >>> > 15mm, >>>> > > but a whole lot better than 50mm, which is what you get with the SLR >>> > pinhole >>>> > > caps. >>>> > > >>>> > > Here is an 8x10 "super" wide angle image: >>>> > > http://www.kencarney.com/Places/tif_0025_std.html >>>> > > And one with the Leonardo 4x5: >>>> > > http://www.kencarney.com/Nature/psd_0041_std.html >>>> > > >>>> > > Best, >>>> > > >>>> > > Ken >>>> > > >>>> > > >>>> > > >>>> > > On 4/27/2011 12:07 AM, Jayanand Govindaraj wrote: >>>> > > >>>>> > >> Looks interesting: >>>>> > >> >>>>> > >> >>>>> > >> >>> > http://theonlinephotographer.typepad.com/the_online_photographer/2011/04/pinwide.html >>>>> > >> >>>>> > >> http://wanderlustcameras.com/ >>>>> > >> >>>>> > >> Cheers >>>>> > >> Jayanand >>>>> > >> >>>>> > >> _______________________________________________ >>>>> > >> 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 >>>> > > >>> > >>> > _______________________________________________ >>> > Leica Users Group. >>> > See http://leica-users.org/mailman/listinfo/lug for more information >>> > >> >> >> -- // richard <http://www.imagecraft.com/> // icc blog: >> <http://imagecraft.com/blog/> // photo blog: <http://www.5pmlight.com> [ >> 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