Apo-Nikkor 150mm F9

All the documentation I've seen on the APO-Nikkor line of photoengraving lenses shows that the shortest focal length available was 180mm, which is too long for practical use on coins. When I saw a 150mm show up on ebay, I grabbed it! 150mm is just on the edge of what is practical for shooting Cents with normal bellows. My copy stand is not tall enough to use it for Dollars but some folks have very tall stands that might work.

The lens is truly apochromatic, which is a rarity. There is absolutely no color shift as I adjust focus. This gives the effect of completely accurate color rendition for single images. On lenses that shift color vs focus (most do) the higher areas will have a slightly different tone than the lower areas. Focus stacking eliminates this problem, since it only includes in-focus pixels, but is much more work than single images.

The disadvantage to these photoengraving/process lenses is their large maximum aperture of f9. The APO-Nikkors won't be winning any contests for pixel-level sharpness. Interestingly, they are the only lenses I've seen that have apertures down to f90 (!!) and this is nominal, not effective. Since they're optimized for around 1:1, this means effective aperture of f180 (!!). This is done when extremely large image circles are required, for instance when reproducing a giant poster. At f9 the image circle is 300mm and it gets bigger for smaller apertures. No problem reproducing a 19mm Cent or 38mm Dollar with these babies.

Apochromatic correction is 380-750nm, a bit wider than the 400-700nm visible spectrum. So they are corrected into the UV and IR spectra.

So how does it perform you ask? As I said, it won't win ultimate sharpness at pixel level given the effective f15 or so for Cents, but for web publishing there is no issue.

Here is a Green/Gold/Salmon streak-toned 1955-S to show the color capability of this lens. This one is hard to get right with most other lenses (except Printing-Nikkor).