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#1
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Petzval original formula? Asymmetrical menisci pair?
I would like to try approximating an old lens a step up from a single
meniscus for experiments with a view camera. I have some 'real' lenses but am really attracted to experiments. I am looking for some guidance, discussion, etc. with finding and interpreting/scaling lens formulae. I have read some patents and browsed the examples in the demo version of the Lensview software. I am remembering that a book is really going to be the answer, but there is so much knowledge on the loose here....I'll start here. Perhaps 99.5% of the readers here don't do this, but I know I have crossed paths with a few who have either built cameras with experimental lenses or know optics well enough to nail down some answers Since it's nearly impossible to procure the exactly ground and spaced components of complex lenses, a meniscus is a safe place to start. I hope to find some quantitative info on the relationship between f.l., iris placement and coverage with a single meniscus lens and a pair of them. The second item of interest is same question(s) for a two-lens setup and position of iris. Then what happens if the lenses are unequal (asymmetrical?). What happens if double convex lenses are substituted for menisci (different type of distortion?) Is this called a single Gauss, or is there not a name for this? Thanks Murray |
#2
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Petzval original formula? Asymmetrical menisci pair?
I hope to find some quantitative info on the relationship between
f.l., iris placement and coverage with a single meniscus lens and a pair of them. Just about any professional optics book will have a graph discribing these relationships with a simple meniscus lens. I believe the only thing that happens by the addition of a second meniscus lens is the correction of distoration. Petzval lenses by design are only sharp at center field. In general, full field performance is usually always lacking. Larry Larry |
#3
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Petzval original formula? Asymmetrical menisci pair?
"Murray" wrote
I would like to try approximating an old lens a step up from a single meniscus for experiments with a view camera. I have some 'real' lenses but am really attracted to experiments. I would suggest getting an "optical bench" - a long stick/rail with sliders on it, each slider holds a lens/group, aperture ... A microscope at one end lets you examine the Arial image. A resolution target is placed at the other end/on the wall/... Commercially made from aluminum extrusion. It is also possible to build one from wood. There should be some home-hobby optics and lasers books with instructions. You may be able to find one at a scientific surplus house. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. psst.. want to buy an f-stop timer? nolindan.com/da/fstop/ |
#4
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Petzval original formula? Asymmetrical menisci pair?
On 3/13/2004 7:29 AM Nicholas O. Lindan spake thus:
"Murray" wrote I would like to try approximating an old lens a step up from a single meniscus for experiments with a view camera. I have some 'real' lenses but am really attracted to experiments. I would suggest getting an "optical bench" - a long stick/rail with sliders on it, each slider holds a lens/group, aperture ... A microscope at one end lets you examine the Arial image. "Arial" image? I hope that was a very obscure tongue-in-cheek reference. (Perhaps a Walt Disney image?) -- The Bush administration should restrain itself from its imperial arrogance that has so alienated countries around the world. Their contempt for the United Nations in the dash to war with Iraq; their support of the coup in Venezuela in April 2002, and the continuing hostility toward President Chavez; the pressure on nations of the world to exempt the US from the International Criminal Court, now joined by their contemptuous attitude toward President Aristide must be halted. It is time for the people of the USA to make this point clear even if the administration continues to walk around with wax in its collective ears, with eyes closed, and ranting about its version of the world as defined by Bush. - Excerpt from TransAfrica statement on the situation in Haiti, 2/17/04 (http://www.transafricaforum.org/) |
#6
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Petzval original formula? Asymmetrical menisci pair?
Thanks all.
Gotta find time to get to local college library. 8020 extrusion is what I was looking at for an 8x10 monorail. Murray |
#7
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Petzval original formula? Asymmetrical menisci pair?
can one calculate or guess the best position for an F stop in an un 'f
stopped' lens ie large projection Petzval I have a 10" 2.8 coated epidiascope lens particularly, (the old Ross carte de visite lens I have has the f stop closer to the front element) regards |
#8
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Petzval original formula? Asymmetrical menisci pair?
Hello Dr. Brian:
Yes, I would be interested in the Petzval details. Thank you |
#9
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Petzval original formula? Asymmetrical menisci pair?
Here's another interesting twist I might try some day.
I'm told eyeglass lenses are ground aspherically. I was 'eyeing' standard diopter 70 mm diameter lens 'blanks' (not yet ground to eyeglass frame shape) for lens experiments, and wondered if the allegedly aspheric curvature was undesireable or not. Thank for reply. |
#10
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Petzval original formula? Asymmetrical menisci pair?
(Murray) wrote in message om...
Hello Dr. Brian: Yes, I would be interested in the Petzval details. Thank you Murray: Below is the prescription from a fairly early but reliable source. Several similar designs appear later in the Zeiss Index. Note that I've guessed the Abbe constants for the glasses since von Rohr only provides index at a single wavelength and no dispersion data. Lens diameter data is also my best guess, but should be fairly close to production designs. The data below are scaled for a focal length of 100. Petzval Portrait Lens From Von Rohr's "Photographischen Objectivs" (1899) SURFACE DATA SUMMARY: Surf Radius Thickness Glass Diameter OBJ Infinity Infinity 0 1 52.9 5.8 1.517000,60.000 30 2 -41.4 1.5 1.575000,41.500 30 3 436.2 23.3 30 STO Infinity 23.3 25.17398 5 104.8 2.2 1.575000,41.500 30 6 36.8 0.7 30 7 45.5 3.6 1.517000,60.000 30 8 -149.5 58.5 30 IMA Infinity 43.59859 Brian www.caldwellphotographic.com |
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