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aspheric lens


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#1 Gill Christie

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Posted 12 June 2006 - 05:35 AM

please can anyone tell me of comparisons/ differences about these two lenses and their effect on the image?, i am just starting out in super 8 and have a braun nizo 6080 and am finding it hard to get sufficient information on the differences between these two types of lenses?
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#2 Alessandro Machi

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Posted 12 June 2006 - 02:22 PM

please can anyone tell me of comparisons/ differences about these two lenses and their effect on the image?, i am just starting out in super 8 and have a braun nizo 6080 and am finding it hard to get sufficient information on the differences between these two types of lenses?


Anamorphic is squeezing more information vertically onto the recording format, and then horizontally stretching it back later during playback.

Aspheric is basically widening the field of view with a lens attachment, (aka wide angle lens, commonly focused via a macro setting), the result is a wider field of view, no adjustment needed when playing back the image.
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#3 Marco Leavitt

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Posted 12 June 2006 - 02:40 PM

Anamorphic is squeezing more information vertically onto the recording format, and then horizontally stretching it back later during playback.

Aspheric is basically widening the field of view with a lens attachment, (aka wide angle lens, commonly focused via a macro setting), the result is a wider field of view, no adjustment needed when playing back the image.



Isn't an aspheric lens more than just a wide angle adapter? In fact, I've seen a fixed lens that was labled aspheric. I was under the impression (and please correct me if I'm wrong) that an aspheric lens is designed to correct for the distortion that you get with many wide angle lenses.
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#4 Leo Anthony Vale

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Posted 12 June 2006 - 02:56 PM

Isn't an aspheric lens more than just a wide angle adapter? In fact, I've seen a fixed lens that was labled aspheric. I was under the impression (and please correct me if I'm wrong) that an aspheric lens is designed to correct for the distortion that you get with many wide angle lenses.


---Most lens elements are spherical.
A common lens problem is spherical abberation in which rays near the edges of the lens elements don't quite hit the focal point. This is causes lens to be at less than optimum sharpness when wide open.
Stopping down the lens cuts off those abberent rays.

Some lens are corrected for this by using non spherical surfaces on some elements.

Canon high speeds and Zeiss suerspeeds have used this technique.
The wide angle attachment for the 10mm switar is asherical to correct for the sperical abberations and maintain edge sharpness, rather than to eliminate distortion.

---LV

Edited by Leo A Vale, 12 June 2006 - 02:57 PM.

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#5 Alessandro Machi

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Posted 12 June 2006 - 03:33 PM

Isn't an aspheric lens more than just a wide angle adapter? In fact, I've seen a fixed lens that was labled aspheric. I was under the impression (and please correct me if I'm wrong) that an aspheric lens is designed to correct for the distortion that you get with many wide angle lenses.


The aspheric wide angle I have used does not seem to distort as much as other wide angle lenses I have seen, so perhaps that is what the word aspheric means.
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#6 Guy Bennett

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Posted 13 June 2006 - 04:58 AM

Leo A Vale is right when he explains that

---Most lens elements are spherical.
A common lens problem is spherical abberation in which rays near the edges of the lens elements don't quite hit the focal point. This is causes lens to be at less than optimum sharpness when wide open.
Stopping down the lens cuts off those abberent rays.

Some lens are corrected for this by using non spherical surfaces on some elements.

Canon high speeds and Zeiss suerspeeds have used this technique.
The wide angle attachment for the 10mm switar is asherical to correct for the sperical abberations and maintain edge sharpness, rather than to eliminate distortion.


An aspherical lens simply means that the lens has one or more elements with aspherical surfaces.
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#7 Alessandro Machi

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Posted 13 June 2006 - 05:43 AM

Leo A Vale is right when he explains that

---Most lens elements are spherical.
A common lens problem is spherical aberration in which rays near the edges of the lens elements don't quite hit the focal point. This is causes lens to be at less than optimum sharpness when wide open.
Stopping down the lens cuts off those aberrant rays.

Some lens are corrected for this by using non spherical surfaces on some elements.

Canon high speeds and Zeiss superspeeds have used this technique.
The wide angle attachment for the 10mm switar is asherical to correct for the spherical abberations and maintain edge sharpness, rather than to eliminate distortion.

---LV



An aspherical lens simply means that the lens has one or more elements with aspherical surfaces.



Here's a quote from the Eumig users manual for a Eumig Aspheric Wide Angle Lens....

....Three times more picture area at the same camera-to-subject distance through the distortion free Eumig PM Aspheric superwide-angle lens.

That quote seems to contradict the statement.... "rather than to eliminate distortion" ....no?
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#8 David Mullen ASC

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Posted 13 June 2006 - 12:28 PM

Isn't "aspheric" a self-defining word? As in "not spherical"?

http://www.kreischer...res/primer.html
http://en.wikipedia....Aspherical_lens
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#9 Dan Goulder

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Posted 13 June 2006 - 12:45 PM

Isn't "aspheric" a self-defining word? As in "not spherical"?

Yes. The design is a physical deviation from a spherical shape, making it more difficult to manufacture. One of my lens sets is aspherical (Canon K35s). They're very sharp, and the focus seems to be consistent all the way to the edges, even with the 18mm, which is physically larger and wider than a comparable Zeiss.
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#10 Gill Christie

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Posted 13 June 2006 - 03:35 PM

Yes. The design is a physical deviation from a spherical shape, making it more difficult to manufacture. One of my lens sets is aspherical (Canon K35s). They're very sharp, and the focus seems to be consistent all the way to the edges, even with the 18mm, which is physically larger and wider than a comparable Zeiss.



Glad i found ye ... thanks a million for the information .... cheers x
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#11 Alessandro Machi

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Posted 14 June 2006 - 09:15 AM

please can anyone tell me of comparisons/ differences about these two lenses and their effect on the image?, i am just starting out in super 8 and have a braun nizo 6080 and am finding it hard to get sufficient information on the differences between these two types of lenses?



How the lens is made doesn't seem to me to be the central question that was originally asked, although it is interesting to learn about.
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#12 Gill Christie

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Posted 15 June 2006 - 01:36 PM

Anamorphic is squeezing more information vertically onto the recording format, and then horizontally stretching it back later during playback.

Aspheric is basically widening the field of view with a lens attachment, (aka wide angle lens, commonly focused via a macro setting), the result is a wider field of view, no adjustment needed when playing back the image.


i just wanted to clarify my use of language in my last post...'ye' meant all posters/contributors and, yes, this info. among other posts including those describing the results observed with the use of an aspheric lens were extremely useful to me thanks again..
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