This is great! You don't even need to "calibrate" the enlarger with a millimeter scale. It's a simple matter of linear proportions. If you use a 35mm negative holder, the opening is about 1 x 1.5 inches., or roughly 25 by 37.5 mm. If you set the enlarger to make an 11x14" print, for instance, one mm at the negative holder will be 11 times as large at the easel or whatever you're focussing on. You can make a scale and then project the pinhole onto it. ----- Original Message ----- From: "Gregg Kemp" <gregg.kemp@???????> To: <pinhole-discussion@p at ???????> Sent: Monday, July 22, 2002 7:03 AM Subject: Re: SV: [pinhole-discussion] pinhole size
> At 08:48 AM 7/22/2002 +0200, you wrote: > >Haven't tried it myself, but I guess it would work: > > > >in your darkroom , you place a transparent ruler somehow in your enlarger > >and mark the mm-steps on a paper. > >Then placing the pinhole-plate in the enlarger, you see if its round and get > >an approximation of the size. > > > >Perhaps you might get an exact measuring doing some maths on the enlargers > >height etc - but thats' beyond my skills for sure. > > > >/peter > > I've used a transparent ruler this way also, but have found that the ruler > is a bit "fuzzy" when projected. As an improvement to this, I made a scale > of 2mm, divided into 1/10th markings (in Photoshop). I printed this onto > transparency film. Then I cut it to fit into the enlarger. Once in the > enlarger, move the enlarger up or down to project the 1mm onto 1cm of the > ruler on the stand. The enlarger is then calibrated. If you cut your > brass shim (or whatever strata you are using for the pinhole) to fit the > enlarger film holder, you can now insert it and measure its size on the > ruler on the stand. I hope this explanation makes sense. I've used this > in a couple of workshops I've done (as a more advanced thing you can do), > and it produced very accurate pinholes for everyone. I think a magnifier > like a Lupe is perfect for checking how well made the hole is, but the > enlarger gives a pretty good measure of its size. > > Here's a pdf version of it if anyone would like to use it: > ftp://ftp.p at ???????/pinholeSizeProjection.pdf > > - Gregg > > > _______________________________________________ > Post to the list as PLAIN TEXT only - no HTML > Pinhole-Discussion mailing list > Pinhole-Discussion@p at ??????? > unsubscribe or change your account at > http://www.???????/discussion/ >
