Lens Coverage - Commercial Ektar Wide Field

Edward M. Cambra

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Aug 9, 1996, 3:00:00 AM8/9/96

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I have been given conflicting information about whether or not
the Kodak Commercial Ektar 190mm lens will cover the 8x10
format. So far, I have seen nothing in print about this, one
way or another. Does anyone have any experience with the
coverage (and resulting movements allowed) for this lens and
this format?

Thanks for the help!

Ed

Robert Gurfinkel

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Aug 9, 1996, 3:00:00 AM8/9/96

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Edward M. Cambra writes:

Thanks for the help!

Ed

_______________________________________________________________________

The Wide Field Ektars cover a maximum of 80 degrees. That gives a top
coverage of 319mm or just barely enough to cover 8x10.

C = 2 * F * tan(angle of coverage divided by two)

The coverage equals twice the focal length times the tangent of half
the angle of coverage.

Bob Gurfinkel, who taught Pythagoras all he knew.

Thor Lancelot Simon

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Aug 9, 1996, 3:00:00 AM8/9/96

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In article <ecambra-0908...@ind-003-236-137.iquest.net>,

Edward M. Cambra <eca...@j-c-l.com> wrote:
>I have been given conflicting information about whether or not
>the Kodak Commercial Ektar 190mm lens will cover the 8x10
>format. So far, I have seen nothing in print about this, one
>way or another. Does anyone have any experience with the
>coverage (and resulting movements allowed) for this lens and
>this format?

To get useful advice, you're going to have to figure out which lens you have.

Do you have a "Commercial Ektar" or a "Wide Field Ektar"? I don't believe
that there's such a beast as a "190mm Commercial Ektar Wide Field".

--
Thor Lancelot Simon t...@panix.COM
"Gee, if your knee jerks any harder you're going to kick yourself in the head."
-- Barry Sherman

Tim Takahashi

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Aug 9, 1996, 3:00:00 AM8/9/96

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In article <ecambra-0908...@ind-003-236-137.iquest.net>,
Edward M. Cambra <eca...@j-c-l.com> wrote:
>I have been given conflicting information about whether or not
>the Kodak Commercial Ektar 190mm lens will cover the 8x10
>format.

You are confusing the Commercial Ektar with the Wide Field Ektar.

The Commercial Ektar's were a serious of f/6.3 Tessar type
lenses made for negatives from 4x5" to 11x14"

The Wide Field Ektars are a series of wide-agnle 4-element
airspaced lenses (again made in a variety of sizes to cover
3.25x4.25 through 11x14")

-tim

Edward M. Cambra

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Aug 10, 1996, 3:00:00 AM8/10/96

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In article <ecambra-0908...@ind-003-236-137.iquest.net>,

eca...@j-c-l.com (Edward M. Cambra) wrote:

> I have been given conflicting information about whether or not
> the Kodak Commercial Ektar 190mm lens will cover the 8x10

> format. So far, I have seen nothing in print about this, one
> way or another. Does anyone have any experience with the
> coverage (and resulting movements allowed) for this lens and
> this format?
>

> Thanks for the help!
>
> Ed

Just to clarify the text of the original post, and make sure
that it agrees with the title, I am referring to the Wide Field
model of the Ektar.

Ed Cambra

John Sparks

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Aug 10, 1996, 3:00:00 AM8/10/96

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I have a 1954 Kodak databook in front of me. They list the 190mm Wide
Field Ektar Lens as suitable for 8x10 with no movements. The listed
image circles are 11 3/16" (284mm) at f/6.3 and 12 1/5" (317.5mm) at
f/16. It will just barely cover 8x10 with no movements at f/16. I
would guess that it has somewhat more coverage at smaller stops (but no
data is given). Ron Wisner has written articles saying that he commonly
uses this lens on 8x10 and that it covers 85 degrees at f/32 (348mm but
I don't understand how he computes his coverage angles, they always seem
too optimistic to me). Hope this helps.

John Sparks