Re: [pinhole-discussion] Zone plates for a body cap
On Thursday, October 24, 2002, at 11:39 PM, Thom Mitchell wrote: 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 Just got the Zone Plates back from the print shop. I made a set of 4 zone plates each with 7 and 21 rings, for use at 50 mm, and one with 7 rings, for use at 75 mm. How about $10 per strip of 4 zone plates- $30 in your case? E-mail me your address, and I'll send the zone plates and a SASE. I might even get to use it soon, if the rain ever stops... Cheers Mike
Re: [pinhole-discussion] Zone plates for a body cap
- Original Message - From: Guillermo pen...@rogers.com I gather that by aperture of the zone plate you mean the size of each of the rings. Mr.Pinhole formula is what the scientific community uses for their high-tech uses of zone plates and my non-scientific tests (focusing aerial images produced by zoneplates) have confirmed that. Other use slightly different formulas. I was reading my own post and it seems not to be too clear. What I meant was that when I mount zone plates on my 4x5 view camera and focus on the aerial image until it is a sharp as they would be, the distance zone plate to film plane matches very closely with what the formula Radius = SQRT(wave length x focal length x ring#) would predict. Now, the formula can also be written as Diameter = 2 x SQRT(wave length x focal length x ring#). Some people use formulas slightly diferent, what they change is that number 2, Patton for instance, uses 1.86 http://www.stanford.edu/~cpatton/zoneplatemath.htm Guillermo
Re: [pinhole-discussion] Zone plates for a body cap
- Original Message - From: Beaker mbea...@mac.com 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? I gather that by aperture of the zone plate you mean the size of each of the rings. Mr.Pinhole formula is what the scientific community uses for their high-tech uses of zone plates and my non-scientific tests (focusing aerial images produced by zoneplates) have confirmed that. Other use slightly different formulas. 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! Just one more suggestion, try making zone plates whose number of clear rings give you f/stops that are equal or slightly smaller (numerically) than a full stop, this will facilitate exposure calculations. Guillermo
Re: [pinhole-discussion] Zone plates for a body cap
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/
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!
Re: [pinhole-discussion] Zone plates for a body cap
Mine bayonet into place, and haven't leaked any light with a pinhole in place. You just have to be a little careful when you get them. Cheers Mike On Thursday, October 24, 2002, at 10:11 PM, John Yeo wrote: Does the pentax K body cap lock into the bayonet mount? The one I have is just a pressure fit, and I am afraid it would come off really easily or leak light. John - Original Message - From: Beaker mbea...@mac.com To: pinhole-discussion@p at ??? Sent: Thursday, October 24, 2002 6:39 PM Subject: [pinhole-discussion] Zone plates for a body cap Hi- 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. Any takers? Cheers Beaker ___ 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/ ___ 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/
Re: [pinhole-discussion] Zone plates for a body cap
- 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
Re: [pinhole-discussion] Zone plates for a body cap
Does the pentax K body cap lock into the bayonet mount? The one I have is just a pressure fit, and I am afraid it would come off really easily or leak light. John - Original Message - From: Beaker mbea...@mac.com To: pinhole-discussion@p at ??? Sent: Thursday, October 24, 2002 6:39 PM Subject: [pinhole-discussion] Zone plates for a body cap Hi- 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. Any takers? Cheers Beaker ___ 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/
[pinhole-discussion] Zone plates for a body cap
Hi- 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. Any takers? Cheers Beaker
