Re: Sundial Trick Photography
The discussion has come back around to perspective correction with a lens and rising-front camera vs. correcting in the digital domain. I have to say that, as much as I like the elegance of the optical/geometric solution, the end result should be at least as good, done in PhotoShop or the like, and, as John Pickard pointed out, the digital camera and software might well cost less than a PC Nikkor lens alone, and certainly less than a quality view camera! You can't handle three-dimensional subjects well with either method - that's a matter of geometry - so go with the system that gives you the most features otherwise... Dave
Re: Sundial Trick Photography
My Nikon Coolpix (stupid name) 990 cost me about $US1000. I got Adobe Photoshop Limited Edition free of charge with the camera. I am not sure what is missing from the Photoshop LE, but it seems pretty complete. The Photoshop Limited Edition (5.0) which came with my earlier Nikon Coolpix was complete - except for the Transform Tools needed for perspective correction! They will be found in the Layers menu if they are present. Ulead PhotoImpact4, sometimes available free with cover disks, will also do good perspective transformations. Les
RE: Sundial Trick Photography
For vertical dials I would still rather stick with an SLR with a long lens (and a tripod!) because of the effects of perspective correction on the gnomon. Incidentally, the effect of a rising front / perspective correction lens can be more or less equalled - at no cost except a smaller image - by resolutely pointing the camera horizontally in front of your eye rather than tilting it upwards. You need a wider angle lens from the same distance, or alternatively have to move further away; and then you need to enlarge the image more as it will include the wall up to the dial and lots of ground (half the picture). Moving further away helps with the gnomon distortion, too - looking at it not up its length. The perspective correction or shift lens (and the view/technical camera equivalent Super Angulons and the like) is very expensive because quite apart from the mechanics it has to produce good images a long way off the optical axis - which is what you are doing when you move it right up its travel to take the high sundial. While John's photo of his Flandrau dial well illustrates the correction of the lines, if you look at the nodus it appears to lie NNE of its shadow, whereas the sun was really somewhere in the SE at the time. That's meant with no disrespect to his adjustment of the view of the dial plane, it's just a fact of geometry. But it occurs to me that one big advantage of a digital camera in all this is that with an ordinary horizontal dial on a high pedestal (not so easy with a very big dial, I agree) you can hold the digital camera at arm's length vertically over the dial and press the shutter, immediately examine the results, and repeat until you're quite satisfied. You will get the proper edge-on view of the gnomon (though its top will appear bigger as it's nearer the camera), whereas correcting perspective of a photo taken from the side appears to fold the gnomon down away from you. When I try this overhead method with a film camera I often wait days or weeks to receive a skewed blurry print of half a dial or one of my own feet. Andrew James
Perspective
Dear friends, I have read your very interesting remarks on perspective. I also have a Coolpix 990 and I am completely satisfied with it. I have solved my perspective adjustements with a Photoshop plugin, the Andromeda Perspective Filter, it is simply wonderful. You can download a demo from the official site http://www.andromeda.com it's worth trying. Sincerely, Paolo *-* Paolo GREGORIO, Via San Rocco 1, VICOFORTE (CN), (Italia) Tel. (home) +39-(0)174-565005, (mobile) +39-339-4416007 e-mails: [EMAIL PROTECTED] [EMAIL PROTECTED] *-*
season dial
Hello, I live on a large piece of property and wanted to build a large "season dial." I imagined being able to get up at sunrise on any morning and be able to see were in the seasonal cycle we were in: how many days left in spring, summer, fall ( also marking equinoxes, olsitices, even metor showers, and the sort) I imagined a large sundial-like device. Are there any plans for something like this? Thanks for your help, Best regards, Mike Deamicis-Roberts
Re: Sundial Trick Photography
Subject: Gnomon nodus distortion As several of you have mentioned, digital or optical photo perspective rectification works great on the sundial's face, but worsens the look of a gnomon or nodus. There are two ways to minimize gnomon and nodus distortion. When taking your picture, stand due south of the dial's center so that your camara lens is in the N/S meridian plane. This way, you see the gnomon edge on. The object being to make it as small and unobtrusive as possible. (Or build your sundials with a thin monofilar cable gnomons!) Or, you can use one of the photo digital editing programs to remove the gnomon or nodus. After you erase the gnomon, you can digitally paint the face where the gnomon was attached (the substyle). Use the color match feature when painting. If I were to go this extra step on my Flandrau dial, I wouldn't erase the cable gnomon since it is so thin that distortion is unnoticible. But I would erase the nodus. Then I would copy and paste a little photo of a round nodus onto the cable gnomon at its proper position over the substyle, south of where it is now. And voila! A perfect photo of the dial face! John John L. Carmichael Jr. Sundial Sculptures 925 E. Foothills Dr. Tucson Arizona 85718 USA Tel: 520-696-1709 Email: [EMAIL PROTECTED] Website: http://www.sundialsculptures.com - Original Message - From: Andrew James [EMAIL PROTECTED] To: sundial@rrz.uni-koeln.de Sent: Wednesday, October 10, 2001 2:55 AM Subject: RE: Sundial Trick Photography For vertical dials I would still rather stick with an SLR with a long lens (and a tripod!) because of the effects of perspective correction on the gnomon. Incidentally, the effect of a rising front / perspective correction lens can be more or less equalled - at no cost except a smaller image - by resolutely pointing the camera horizontally in front of your eye rather than tilting it upwards. You need a wider angle lens from the same distance, or alternatively have to move further away; and then you need to enlarge the image more as it will include the wall up to the dial and lots of ground (half the picture). Moving further away helps with the gnomon distortion, too - looking at it not up its length. The perspective correction or shift lens (and the view/technical camera equivalent Super Angulons and the like) is very expensive because quite apart from the mechanics it has to produce good images a long way off the optical axis - which is what you are doing when you move it right up its travel to take the high sundial. While John's photo of his Flandrau dial well illustrates the correction of the lines, if you look at the nodus it appears to lie NNE of its shadow, whereas the sun was really somewhere in the SE at the time. That's meant with no disrespect to his adjustment of the view of the dial plane, it's just a fact of geometry. But it occurs to me that one big advantage of a digital camera in all this is that with an ordinary horizontal dial on a high pedestal (not so easy with a very big dial, I agree) you can hold the digital camera at arm's length vertically over the dial and press the shutter, immediately examine the results, and repeat until you're quite satisfied. You will get the proper edge-on view of the gnomon (though its top will appear bigger as it's nearer the camera), whereas correcting perspective of a photo taken from the side appears to fold the gnomon down away from you. When I try this overhead method with a film camera I often wait days or weeks to receive a skewed blurry print of half a dial or one of my own feet. Andrew James
Re: Dials using unfolded analemmas; Singleton
Mac Oglesby wrote: Hello fellow sundial lovers-- The September issue of the Bulletin of the British Sundial Society contains (pages 127-9) an article by Herbert Wright detailing how he designed and constructed, while interred in a Japanese prison camp in Lunghua, China, a marble sundial which uses unfolded analemmas to display clock time. Mr. Wright overcame enormous obstacles in creating his dial, and it took him more than a year. The dial is dated 1944, as far as I can tell. I have a scanned image of the dial available upon request. It's an 80k JPG file. Prior to seeing this article the earliest use of unfolded analemmas for EoT correction I had run across was a dial visited in Montreal during the 2001 NASS conference. A monumental equatorial sundial (1967) at the Planétarium de Montréal by Herman van der Heide, of The Netherlands, utilizes unfolded analemmas along its equatorial band. A nice touch on this dial is the use of different colors to aid the eye in following the date arcs. I have a 44k JPG file of this dial available upon request. My questions to Sundial List members: Do any of you know of an earlier (than 1944) dial using unfolded analemmas to supply the EoT correction, or of early published material concerning this? Is it known who was responsible for discovering the principle? Best wishes, Mac Oglesby Brattleboro, Vermont USA This design is, surely, exactly what we were here debating around February last year (see BSS Bull 2000.1 p 51, Mac's email of 28 Feb 2000). At that time, it was proposed to call it a Singleton dial. It now seems more appropriate to call it a Wright dial, if indeed Herbert Wright invented it. Chris Lusby Taylor Newbury, England 51.4N, 1.3W.
Re: Dials using unfolded analemmas; Singleton
Hello fellow sundial lovers-- The September issue of the Bulletin of the British Sundial Society contains (pages 127-9) an article by Herbert Wright detailing how he designed and constructed, while interred in a Japanese prison camp in Lunghua, China, a marble sundial which uses unfolded analemmas to display clock time. Mr. Wright overcame enormous obstacles in creating his dial, and it took him more than a year. The dial is dated 1944, as far as I can tell. I have a scanned image of the dial available upon request. It's an 80k JPG file. Prior to seeing this article the earliest use of unfolded analemmas for EoT correction I had run across was a dial visited in Montreal during the 2001 NASS conference. A monumental equatorial sundial (1967) at the Planétarium de Montréal by Herman van der Heide, of The Netherlands, utilizes unfolded analemmas along its equatorial band. A nice touch on this dial is the use of different colors to aid the eye in following the date arcs. I have a 44k JPG file of this dial available upon request. My questions to Sundial List members: Do any of you know of an earlier (than 1944) dial using unfolded analemmas to supply the EoT correction, or of early published material concerning this? Is it known who was responsible for discovering the principle? Best wishes, Mac Oglesby Brattleboro, Vermont USA This design is, surely, exactly what we were here debating around February last year (see BSS Bull 2000.1 p 51, Mac's email of 28 Feb 2000). At that time, it was proposed to call it a Singleton dial. It now seems more appropriate to call it a Wright dial, if indeed Herbert Wright invented it. Chris Lusby Taylor Newbury, England 51.4N, 1.3W. Hi Chris, I guess at this point I'm more interested in tracing the history of the concept and enjoying seeing various realizations than proposing or voting on labels. But I am hoping that someday I'll learn the name of the person who deserves credit for originating the concept. Regards, Mac
