ACHROMATIC macro lens


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sgfriend

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Dec 20, 2005
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Pasir Ris
#3
What i have was a Sigma achromatic macro lens. So when I set the Sigma 70-300mm into macro mode and use it to become macro and more macro?:dunno:
 

blurblock

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May 30, 2003
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#4
sgfriend said:
What i have was a Sigma achromatic macro lens. So when I set the Sigma 70-300mm into macro mode and use it to become macro and more macro?:dunno:
Yes ... it is basically a magnifying glass.
 

sumball

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Jul 8, 2003
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#6
Mr blurblock is still the most helpful CSer.
 

student

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Jul 26, 2004
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#7
There are two aspects to the description of this lens

1 Achromatic

2 Macro

"Macro" as explained by blurblock is a "magnifying glass"

Now for "achromatic".

A single lens causes colored fringes around images because the lens diffracts the different wavelengths in white light to slightly different extents.

An "achromatic" lens uses a combination of lenses to reduce this color aberration.
 

sgfriend

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Dec 20, 2005
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Pasir Ris
#8
student said:
There are two aspects to the description of this lens

1 Achromatic

2 Macro

"Macro" as explained by blurblock is a "magnifying glass"

Now for "achromatic".

A single lens causes colored fringes around images because the lens diffracts the different wavelengths in white light to slightly different extents.

An "achromatic" lens uses a combination of lenses to reduce this color aberration.
Oh :confused:
 

MDZ2

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Feb 23, 2005
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#9
I think the term is Apochromatic or APO for short. These are coatings on lenses that filter out different wavelengths of light. Without these, you will tend to get images with chromatic aberations or rainbows at the edges of images. its especially pronounced when using long lenses and in broad daylight.
 

Dennis

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Jan 24, 2002
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#10
Not necessary Apo.

Read this

http://www.redoptronics.com/achromatic-lenses.html

MDZ2 said:
I think the term is Apochromatic or APO for short. These are coatings on lenses that filter out different wavelengths of light. Without these, you will tend to get images with chromatic aberations or rainbows at the edges of images. its especially pronounced when using long lenses and in broad daylight.
 

blurblock

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May 30, 2003
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#11
MDZ2 said:
I think the term is Apochromatic or APO for short. These are coatings on lenses that filter out different wavelengths of light. Without these, you will tend to get images with chromatic aberations or rainbows at the edges of images. its especially pronounced when using long lenses and in broad daylight.

Achromatic is Achromatic .... Apochromatic is Apochromatic ..... two different animals altogether.....
 

Jan 23, 2005
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#12
MDZ2 said:
I think the term is Apochromatic or APO for short. These are coatings on lenses that filter out different wavelengths of light.
It has nothing to do with coatings. A basic achromat is made from two lenses of different optical glass, so that the chromatic abberations of one lens cancel those of the other. In general, this works exactly only for two wavelengths (for other wavelengths, chromatic abberation is reduced, but not eliminated).

Apochromats are corrected for three wavelengths and are not the same as achromats.
 

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