Didn't finish reading all the posts, I would be interested in a 7 ring and a 21 ring for 50 mm, say $10 each (negotiable of course), plus maybe one in the 75mm range for starters. Flexible, again let me know what you want because this sounds like a great way to get into zone for not a ton of money. Thanks again, Thom
tjmi...@ix.netcom.com ----- Original Message ----- From: "Beaker" <mbea...@mac.com> To: <pinhole-discussion@p at ???????> Sent: Thursday, October 24, 2002 11:24 PM Subject: Re: [pinhole-discussion] Zone plates for a body cap > > On Thursday, October 24, 2002, at 10:28 PM, Guillermo wrote: > > > > > ----- Original Message ----- > > From: "Beaker" <mbea...@mac.com> > > > >> I'm thinking of getting a sheet of Zone Plates made for a Pentax K > >> mount body cap (optimized for 43 mm). Would anyone be interested in > >> buying any? The reason I ask, the negative will cost something like > >> $50 > >> to $75, (the shop has a $50 minimum.) and I would like to spread the > >> cost out a little. For a little more to cover the cost of a body cap, > >> I > >> could send out the finished article. The negative isn't made yet- I'm > >> just trying to gauge the interest, so the price is still "to be > >> determined". > > > > A sheet made by an image setter can fit lots of ZPs, you don't have to > > have > > the whole sheet full of 43mm ZPs, I would suggest you make some other > > focal > > lengths as well. 65mm for instance is perfect for attaching it to the > > back > > of the shutter of a Lubitel. Another possibility, which is not > > mutually > > exclusive with the one previously mentioned, is to make similar focal > > lengths ZPs but with different number of rings, which will give you > > different f/stops, I.E., a 43mm ZP with 9 total rings is f/64 (aprox) > > but a > > 19 rings one is f/45 and would probably have more of that ghostly > > effect. > > > > I make my own ZPs using lith film, otherwise I'd be joining you, > > nevertheless I recognize this as a good chance for those that have not > > experimented zoneplate photography to try it with very minimum > > investment > > and help you share the cost in the process, a win/win scenario if you > > ask > > me. > > > > Good luck. > > > > Guillermo > > > > All Good points- thanks! I was tinkering around with Mr. Pinhole's zone > plate generator, and had already made up smallish group of 43 mm, 7 > ring (I think) zone plates. That is what I had in mind with the first > post. If there is any interest, I could just as well make up a group of > custom zone plates. > > Guillermo- how do you figure out the aperture of a zone plate? Mr. > Pinhole mentions this formula: <radius = sqrt(wavelength * > focallength * ring)>. I was guessing that this would give a good number > to start with. Is this a good guess? > > One last thing- I've never worked with zone plates before, or even have > litho negatives made, so we will learn together what works, and what > doesn't! > > > _______________________________________________ > 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/
