I have a pdf of the Nikon LF lens brochure from 2004 that says the Nikkor-AM ED 120mm f/5.6 lens has an image circle of 210mm at f 5.6, and 250mm at f22.
I have a pdf of the Nikon LF lens brochure from 2004 that says the Nikkor-AM ED 120mm f/5.6 lens has an image circle of 210mm at f 5.6, and 250mm at f22.
... JMOwens (Mt. Pleasant, Wisc. USA)
"If people only knew how hard I work to gain my mastery, it wouldn't seem so wonderful at all." ...Michelangelo
I have the same brochure in PDF. It doesn't explicitly say so, but the image circle numbers are based on 1:1 magnification. The spec table gives a 55 degree f/22 angle of coverage; plugging this into the formula for image circle at infinity gives a 125mm image circle. Nikon says 250mm, which can only be correct at 1:1 as the image circle at 1:1 is twice that at infinity.
Of course, this doesn't address the OP's original question about the range of "optimum performance".
Regarding MarkJ's comment in post 7, Rodenstock's literature says the 120mm and 180mm Apo-Macro-Sironar have 6 elements in 4 groups, so the design differs from the Nikkor-AM (he is correct that Schneider's Makro-Symmar is an 8-element design). The Apo-Macro-Sironar's 1:1 coverage is 336mm, significantly more than the Nikkor-AM's 250mm.
I have no info on the Apo-El-Nikkor so can't say whether the Nikkor AM is or isn't similar.
Last edited by Steve Goldstein; 5-May-2024 at 03:42.
I must look into the Macro Sironar data, I had not realised that it might only be 6 elements. The Schneider's are.
The Apo El-Nikkor is 8 elements and the central doublets have a fluor-crown for special levels of colour correction.
The image circles are usually quoted for the most flattering mag, which is 1:1
From Rodenstock literature that I have:
Macro-Sironar(-N) (210mm, 300mm) is 6 elements/4 groups, performance specified for range 1:3 - 3:1 with cell interchange.
Apo-Macro-Sironar (120mm, 180mm) cross-section not provided, but performance specified for range 1:5 - 2:1 with no cell interchange needed.
What's the part about cell interchange ?
Have you got a link to the brochure ?
From the brochure re the 210 and 300:
"The front and rear components of the six-element Macro-Sironar-N are removable and interchangeable. In its normal configuration the lens yields excellent definition at reproduction scales between about 1:3 and 1:1. With the elements interchanged, the optical system yields the same optimum definition in the range from 1:1 and 3:1. Memory aid symbols on each side of the mount indicate the scale range for each configuration."
Here's a current eBay listing that clearly shows the "memory aid symbols":
https://www.ebay.com/itm/296339796028
Here's a link I just found to the dedicated brochure for the later 120/180 Apo-Macro-Sironar - evidently those are asymmetrical 6/4 designs as well:
https://nielspn.dk/files/apo-macro-sironar.pdf
It's the same as reversing the lens, which lots of macro lenses recommend doing once you pass 1:1. If the lens has a symmetrical design, reversal is irrelevant.
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