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Petzval original formula? Asymmetrical menisci pair?



 
 
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  #1  
Old March 13th 04, 03:38 PM
Murray
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Default 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  
Old March 13th 04, 04:06 PM
Hemi4268
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Default 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  
Old March 13th 04, 04:29 PM
Nicholas O. Lindan
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Default 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  
Old March 13th 04, 08:07 PM
David Nebenzahl
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Default 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/)

  #5  
Old March 14th 04, 12:31 AM
brian
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Default Petzval original formula? Asymmetrical menisci pair?

(Murray) wrote in message om...
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



Murray:
Warren Smith's "Modern Optical Engineering" and Rudolf Kinglake's
"Lens Design Fundamentals" both contain in-depth discussions about
single element meniscus landscape lenses. In general, the meniscus
shape and stop position are chosen to correct coma and introduce
overcorrected astigmatism which partially balances the inherent field
curvature. A system of two identical meniscus landscape lenses
arranged symmetrically about the aperture stop is called a periscopic
lens. As Larry points out above, such a lens will be corrected for
distortion, but in addition it will be automatically corrected for
lateral chromatic aberration and any residual coma. Breaking the
symmetry of a periscopic lens was tried by Zentmayer in the 1860's,
but without much benefit. Note that if the meniscus elements are made
meniscus enough, then the field curvature can be fully corrected, and
the periscopic lens can become a Hypergon covering up to 140 degrees
without any trace of distortion.

If you use bi-convex instead of meniscus elements then the spherical
aberration will be better corrected, but field aberrations become
terrible. This is vaguely similar to the Petzval design, but a true
Petzval offers a bit more opportunity for field correction. The
system you describe is definitely *not* a double-Gauss. Kinglake's
book has a good discussion about the development of the Petzval lens.
The demo version of LensVIEW doesn't have the original Petzval design,
although U.S. 1,415,002 is a close relative. I'm the author of
LensVIEW, and I can give you the original Petzval prescription if you
need it.


Brian
www.caldwellphotographic.com
  #6  
Old March 14th 04, 12:33 AM
Murray
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Default 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  
Old March 15th 04, 01:31 PM
asc
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Default 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  
Old March 15th 04, 03:07 PM
Murray
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Default Petzval original formula? Asymmetrical menisci pair?

Hello Dr. Brian:

Yes, I would be interested in the Petzval details.

Thank you
  #9  
Old March 15th 04, 05:35 PM
Murray
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Default 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.
 




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