Author Topic: Repro Nikkor anyone?  (Read 10810 times)

Akira

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Re: Repro Nikkor anyone?
« Reply #30 on: November 14, 2015, 16:56:14 »
Akira, hello .... that seller IS Kiril Arsov himself, I thought that got clear...  ;) ;) ;)

If you look at his completed auctions, its gets very clear that those are very inflated...
http://www.ebay.com/sch/m.html?item=262131394721&rmvSB=true&LH_Complete=1&_ssn=ultramicronikkor&LH_PrefLoc=2

Nearly $1.200 for a FUJINON 0.85/25mm is at least a factor three too high ...

Klaus, thanks for straightening things up!  Congratulations on his successfully set the standard for the COM-Nikkor 37/1.4.  :D

Your maple leaf image looks nice!  The Visionar seems to be sharper than the Rodenstock with the same spec.
"The eye is blind if the mind is absent." - Confucius

"Limitation is inspiration." - Akira

Dr Klaus Schmitt

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Re: Repro Nikkor anyone?
« Reply #31 on: November 23, 2015, 17:37:23 »
Thanks Akira, appreciate it.
formerly known as kds315

Royal Winchester

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Re: Repro Nikkor anyone?
« Reply #32 on: December 04, 2016, 22:12:17 »
Hopefully some of you lens design geniuses can educate me.
I understand the F-number of a typical photography lens to be focal length divided by entrance aperture diameter.
If I'm right, that is based on focus at infinity.
Some of my macro lenses will start to read smaller apertures as I focus closer.  Hence the effective f number goes up.
I have the 85mm Repro and it is wonderfully sharp, and resolves a lot of detail.  I like it for focus stacking in the 1:1 - 1.75:1 mag range.
However, it has 48mm threads so it has no where near an 85mm aperture.  Is that why it is listed as an effective aperture of less than 1.0?
Does that affect DOF and light gathering equally?
It is certainly very bright and has razor thin DOF at f1.0!

-Royal

Bjørn Rørslett

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Re: Repro Nikkor anyone?
« Reply #33 on: December 04, 2016, 22:38:19 »
The entrance pupil of the Repro-Nikkor 85 mm f/1 is 87 mm in diameter. Hence its f-number, by definition,  is f/1.

As the lens is perfectly symmetric, its effective aperture at 1:1 is f/2.

(standard equation) Neff=N*(1+m)
where N=f-number and m=magnification (pupil factor =1 in this case)

It is worth remembering that the pupils are virtual quantities and thus not directly physically linked to the lens measurements. The pupils can be in- or outside the lens assembly.

To your last questions, 'no' is the answer to both. Magnification is already factored into the 'DOF' equation. The entrance pupil is the depiction of the physical aperture (opening), so is a virtual quantity, and acts as the collector of light on behalf of the optical assembly.

Royal Winchester

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Re: Repro Nikkor anyone?
« Reply #34 on: December 05, 2016, 01:16:30 »
Thank you, Bjorn

So the entrance pupil is what I "see" when I look through the lens, and it appears that there is a large circle of light - larger than the actual lens.  That's the 87mm pupil I see, I take it.
Appreciate the quick response!