APO-Nikkor vs Process Nikkor

[David G. Gagnon]

While browsing that popular auction site, I came across something in a description for a 210mm f10 Process Nikkor lens that made me say "Hmmmmm....."

"The f-stop range is F10 to 32. This lens will cover an 8x10 image comfortably; coverage is 72 degrees at F22. (The F10 process Nikkors have 40% more coverage than the standard F9 Apo-Nikkor types.) "

This is part of what the seller said. If the part about 40% more coverage is true, can anyone explain why? Also, will the f stop only stopping down to f32 be a drawback to using this lens with a packard shutter. Getting it mounted into a shutter with an iris that will stop down more will be cost prohibitive for me.

Thanks in advance.

DG

[Michael S. Briggs]

The coverage of a lens is a characteristic of the design. The Apo-Nikkors and the Process-Nikkors have different designs. Most of the Apo-Nikkors were rated by Nikon as covering 46 degrees. I'd call 72 vs 46 degrees to be more than 50% more.





The Process-Nikkors were Nikon's offering for those who wanted a wider-coverage process lens. A typical use would be in a vertical process camera, which would have less distance between the orignal and the film than most horizontal process cameras, and so need a shorter focal length lens. If you shorten the focal length of the lens, but want to maintain the ability to cover the same size original, you need a larger coverage angle -- hence the Process-Nikkor.





A previous thread: Origional designed use for Nikkor 260f10 at http://www.largeformatphotography.info/lfforum/topic/310389.html.

[Steve Hamley]

Schneider also made wide angle G-Clarons for the same purpose. As an alternative, you might want to look at a 210 mm G-Claron, especially if you can find one in a barrel as it will usually screw directly into a Copal 1 shutter, so all you would need made is an aperture scale, which you could do yourself. S. K. Grimes lists the process or wide angle Nikkors as being difficult or expensive to mount. Apparently there's no screw-in ring holding the glass in the barrel; the barrel is just "rolled" or swaged in, requiring that the glass be cut out of the barrell for shutter mounting.

As far as the coverage goes, I would guess (and I am guessing) that the wider angle version is a 6 element/4 group plasmat (like the G-Claron), where the regular version would be a 4/4 dialyte like the Artar. The stated coverage angles seem to be about right for this to be true.

Steve

[Bob Salomon]

As were the Apo Geronars, Apo Graphigon and Apo Geronar S. They covered, depending on the lens, 70 to 78° and were designed for vertical process cameras.

[Arne Croell]

The Process Nikkor as well as the G-Claron WA are not Plasmats, but a double Gauss design (4 elements/4 groups), similar to the Kodak WA Ektar or the Meyer Aristostigmat. Both the Process Nikkor and the G-Claron WA are probably completely symmetric, being optimized for 1:1. They consist of 4 deeply curved menisci - the telltale sign, apart from the reflections, is that the curvatures of both the outer and the inner glas surfaces for each cell are usually much higher than for a Plasmat.

[David G. Gagnon]

Thanks to all for the responses.

I have seen these lenses for sale in the past and thought that they were the same lens with a different name/ aperture. Sounds like this would be good for an 8x10 vertical enlarger to make larger prints than with the standard lens.

Thanks!

DG