Mark, I think you are still confusing process lenses with macro lenses. All of the modern macro lenses are f5.6 lenses.
Mark, I think you are still confusing process lenses with macro lenses. All of the modern macro lenses are f5.6 lenses.
I haven't found f/5.6 lenses to be noticeably better on the groundglass than f/9 lenses. For macro work in LF, effective apertures are so small even for focusing that the solution isn't a brighter lens but a small, bright flashlight.
Bob S.
If one wants to reproduce a flat field to film (another flat field), you are suggesting a process lens, vs. a macro lens, is this correct? I assume the difference is, the flat field lens is designed to have the plane of sharp focus reach into the corners of the subject, which is unlike the plane of sharp focus for a normal lens, which the plane of sharp focus is of equal distance from the lens, forming a plane of sharp focus in a semi circle, with the center of the lens being one end of the radius, the other end of the radius forming the semi circle. Is this correct?
If so, what Rodenstock lenses are designed specifically for flat field task?
Also, I want to do flat field work, such as shooting a flat 24x30" subject to MF film, 1:12 reduction. This is obviously not macro or high magnfication, but rather similar to normal photography, however, the subject is very close (similar to macro) and the desire is to have the Plane of sharp focus be flat at the subject. What lens does this best, and how does one choose the best fl for this type of work?
TYIA
"Mark, I think you are still confusing process lenses with macro lenses. All of the modern macro lenses are f5.6 lenses."
Right you are, Ted! For the little use it would probably see, I'd rather spend less for a process lens that could pass as a macro, but that's not being realistic, just cheap. Thanks for keeping my terminology straight before I confused someone else.
As JohnArs said, all modern LF lenses are designed to be flat field. This shouldn't be a problem at taking aperture.
I am having difficulty making sense of Bob's recommendation that Process lenses are intended for 2D subjects and Macro lenses for 3D subjects. The sense I can make out of this is that most (but not all) LF Process lenses are relative narrow field, while all of the current LF Macro lenses (plus the just discontinued AM-ED Nikkor) have wide coverage. For a 2D subject the photographer is likely to center the camera on the subject and not to use any movements. For a 3D subject, they are likely to want to use tilts and swings to place the plane of best focus. So for 3D subjects, a lens with extra coverage (i.e., a Macro lens) will tend to be more useful than for 2D subjects. But the Macro lens will work very well for the 2D subject, it will just have excess coverage. And the Process lens will work for 3D subjects if you don't need movements, or use a long enough focal length, or work at a sufficiently high magnification.
Ted pointed out the other obvious difference between LF Process and Macro lenses: most of the Process lenses are f9, while the LF Macros are f5.6.
As to the original question about when one should switch from a normal taking lens to a macro lens, assuming that you have both, probably around 1:5. What's confusing is that the answer is fuzzy -- there isn't a sharp boundary where one lens type becomes clearly superior -- there is a large overlap. What matters to the corrections of a lens is the angles that the light rays make in traveling from subject to lens to image. There is little difference in the angles from 1:infinity to 1:20. As you focus from 1:10 to 1:5 to 1:1 the angles start changing rapidly.
My experiment with this question compared a Fuji-W and a G-Claron doing a closeup of a flat subject. The resulting negatives were virtually identical. But wide-open and near wide-open, the Fuji-W could only be focused in the very center of the image because the rest of the image was too fuzzy.
I would love to hear a lens designer's take on the design tradeoffs and differences between a LF macro lens optimised for 1:3 and process lenses and enlarging lenses optimised for the same ratio.
I read Bob's comment about 2D and 3D as being back-to-front. The point about the '2D' lenses like APO-Ronars and G-Clarons is that they had to have very low distortion for accurate reproduction of things like technical drawings and maps. They also had to have true apochromatic performace for making colour seperations. That means that the design will have been optimised for low distortion and near-identical performance at the center wavelengths of the standard colour seperation filters, which leaves less wiggle room for improving other aspects of the lens' performance. If you allow a little distortion, or if you improve the perforamce across the whole visible spectrum at the expense of loosing true apochromaticity, you will probably end up with a better lens for more general subjects, or one which works better at wider apertures.
"If so, what Rodenstock lenses are designed specifically for flat field task?"
Apo Ronars but they are out of production.
Struan, I think almost all of the LF macro and process lenses are symmetrical, and thus optimized for 1:1. From the symmetry, they will have zero distortion for 1:1 and tend to have low distortion. Schneider's datasheet for the Macro-Symmar shows distortion below 0.5%, which is very low, albeit somewhat worse then what an old datasheet shows for the 240 mm Apo-Ronar -- a price of the wider field.
The only process or macro lens that I can think of that isn't symmetrical is the Rodenstock Apo-Macro-Sironar, which is "biased" to have a intended use range of 1:5 to 2:1.
At this point the nomenclature process lens vs macro may be more of historical interest than useful in selecting a lens. I suggest looking at coverage and maximum aperture (if that is important to you). There are some wide-coverage process lenses available in shutter (e.g., G-Claron, Fuji-A).
Mark: of the lenses that you list, for working at 1:1, I'd try the G-Claron, Eskofot Ultragon, and Hexanon GR-II. At least the G-Claron (and probably the others) are symmetical and will do very well for 1:1. If focusingis difficult, try bringing on more light (perhaps a flashlight). Is your darkcloth fully opaque? As Dan pointed out, unless depth of field requires f45, it is best to avoid stopping down so far.
Michael, don't forget about Apo Tessars, TTH tessar type process and copying lenses, tessar type Apo Nikkors, Apo Germinars, various tessar type process lenses from the FSU, ...
I'm not sure whether Apo Skopars, which, name notwithstanding, are 5/3 heliar types, are quite symmetrical. Boyer has asserted that Apo Saphirs, also 5/3 heliar types, are symmetrical. That claim notwithstanding, their diaphragms have to be on one side or the other of the central singlet; I have two, one with the diaphragm in front, the other behind, the central singlet. Go figure ...
Cheers,
Dan
Dan, I just went back over some of the earlier answers in this thread and noted yoru comments on your 35mm Nikkors. My comments here have been addressed specifically at LF lenses and their design. I also took a quick romp through Lefkowitz' book and am not sure it is that good a reference for someone interested in LF macro photography as it seems almost totally aimed at 35mm macro work and, while it is good information for that purpose I am not so sure for LF work.
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