Nikkor 120mm f5.6 AM ED Macro: Optimal Range, vs. Optimal Magnification

[JMO]

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.

[Steve Goldstein]

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 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.

[Mark J]

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

[Oren Grad]

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.

[Mark J]

What's the part about cell interchange ?
Have you got a link to the brochure ?

[Oren Grad]

What's the part about cell interchange ?

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

[xkaes]

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.

[Oren Grad]

It's the same as reversing the lens...

It is indeed reversing the lens, just with the convenience of being able to leave the lensboard-mounted shutter as is.

[neil poulsen]

It supposedly makes an APO quality 2x enlarging lens for 4x5 negatives. I haven't tried it that way yet.

I was wondering about that, because the 120mm AM ED has some similar design and glass elements as the Apo El Nikkor enlarging lenses.

[neil poulsen]

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.

Thank you for this information.