Macro versus Process Lenses ?
We know that Process lenses were made for process cameras, not LF cameras. We know that Macro lenses for LF are mounted in shutter, have more elements, and open wider than Process lenses. The diaphragms are different, because of whatever the shutter provides versus whatever barrel-lenses give - which is usually more blades. Coverage may differ also.
However, sweeping all of that aside, is there a qualitative difference in resolution or image quality ? In other words, if we shoot close to 1:1, and stop both lenses down to say f/16, will we see much of a difference in image quality ?
Re: Macro versus Process Lenses ?
Of two dimensional or three dimensional objects?
Re: Macro versus Process Lenses ?
Thanks Bob: 3-dimensional subjects. Pumpkins, tulips, dishes, etc.
I hadn't considered that :)
Re: Macro versus Process Lenses ?
Then a macro lens will easily outperform a process lens, especially away from the center of the format.
And process lenses, 600mm or shorter, were designed to be only used at f22 for their optimal results. A macro lens will perfom optimally over a range of aperture to f22, including f16.
Also, if preserving the shape of the originals a long macro lens like a 300mm is required to reduce foreshortening.
Re: Macro versus Process Lenses ?
Quote:
Originally Posted by
Bob Salomon - HP Marketing
Then a macro lens will easily outperform a process lens
In what ways?
Re: Macro versus Process Lenses ?
Bob, could you please expound a bit about how a process lens would have less performance with three-dimensional objects? I would think the depth of field would be similar at identical f/stops.
Also, weren't process lenses designed to take a variety of aperture shapes and sizes, hence the Apo-Ronars that close to f/260 and has a slot for Waterhouse stops?
I'm quite curious, as I've always used prcess lenses for my close-up work with very good results.
Re: Macro versus Process Lenses ?
Incidentally, here's my understanding of the differences between "general-purpose/macro/process" lens types:
A "general purpose" lens is optimized for use from infinity to near 1:1 at the film plane, and is well-corrected for all aberrations.
A "macro" lens is optimized for use at 1:1 and greater magnifications, and is well-corrected for all aberrations.
A "copy/process/graphic arts" lens is optimized for "close distances" (usually about 4:1 to 1:4), and is especially well-corrected for geometrically-distorting aberrations such as pin-cushion and barrel distortion so that "artwork" is not distorted when rephotographed for the printed page. Special attention is paid to making them as apochromatic as possible, though in modern lenses, all are apochromatic for nearly all practical purposes. Keeping the lens to these specifications usually means a smaller maximum aperture.
And I believe (someone correct me if I'm wrong) that eliminating focus shift is also a prime concern in making process lenses.
Any other differences I don't know of that someone can chime in on?
__________________
Re: Macro versus Process Lenses ?
Quote:
Originally Posted by
Mark Sawyer
Bob, could you please expound a bit about how a process lens would have less performance with three-dimensional objects? I would think the depth of field would be similar at identical f/stops.
Also, weren't process lenses designed to take a variety of aperture shapes and sizes, hence the Apo-Ronars that close to f/260 and has a slot for Waterhouse stops?
I'm quite curious, as I've always used prcess lenses for my close-up work with very good results.
I can quote from specific examples. The May Company set up a super studio in St Louis for their catalog photography. After extensive testing with process lenses and macro lenses (all matched for performance at the factory in Germany) they found that best results were delivered by macro lenses when using 3-dimensional objects and the the results were simply more pleasing for reproduction in a catalog, where they were offering products for sale. Especially better were the reproduction of delicate, detailed items, like jewelry, at the edges and corners when the subject was not confined to the center of the field. It was not a matter of depth of field, it was how the subject was reproduced.
We had a similar situation with Dixie Cups studio in PA where they had to reproduce the cups and plates that they produced for various companies like MacDonalds and needed the most realistic reproduction and detail at 1:1 of the product for record shots.
BTW, macro lenses, like the Rodenstock Macro Sironar (discontinued) Apo Macro Sironar and Apo Macro Digital Sironars are not optimized for 1:1. They are optimized for a range of reproductio. The Macro Sironar was corrrected for 1:3 to 3:1 (depending on the orientation of the elements). The current macro lenses are corrected for 1:5 to 2:1 without changing the orientation of the elements.
A general purpose lens like the Apo Sironar S is corrected for 1:10 giving a working range of 1:5 to infinity. The Apo Sironar N, and similar lenses from other manufacturers, is corrected for 1:20 for ratios from 1:10 to infinity.
Neither type is corrected for "near 1:1".
Re: Macro versus Process Lenses ?
Every lens shows only a two-dimensional plane with optimum performance - depth of field is only an optical illusion - so there is no difference between two-dimensional and three-dimensional subjects for a certain image scale the lens is made for.
Macro-lenses have compared to process-lenses a bigger angle of view and a larger aperture, so more lenses are needed to get, more or less, the same performance as with a process-lens f/9.
The apochromatic correction used with process-lenses is needed to get the same image-dimension also with blue, green and red filtered images but it helps also to get more saturated colors without filters.
The small f-stops like f/264 and also the different aperture shapes are used to influence the shape of the typographical point by diffraction.
Peter
BTW to show a pumpkin at 1:1 one needs at least ULF. :D
Re: Macro versus Process Lenses ?
Mark, not all of y'r definitions are generally accepted.
General purpose lenses are usually made to be used at magnifications of 1:10 and lower. In my book, 1:10 isn't very near to 1:1.
Macro lenses are made to be used in the range 1:1 to sometwhat lower often 1:10, when mounted normally. But there are macro lenses made to be used over a considerable range, e.g., the 100/6.3 Luminar; per Zeiss' propaganda it should be used from 1:8 to 8:1.
That said, there's no consistently-applied naming convention that's applied to lenses made for close-up photograph (1:1 to 1:10) and photomacrography (1:1 and higher). Each maker has his own way ...
Many process lenses are symmetrical (front cell identical to rear), so are best at 1:1 by construction. Some types, e.g., dialytes hold their corrections very all at low magnifications. At one time Rodenstock's propaganda asserted that Apo Ronars were better at infinity than telephoto lenses. This isn't true of modern teles.
But and however, there are some asymmetrical process lenses, e.g., TTH Apotals and "Copying Lenses," which are f/9 tessar types. Mine are very good at all distances. From which I conclude that reasoning from theory is nice but measurement is necessary too.
Ken, to address what I think you really want to know, in my lens trials macro lenses made for use around 1:1 were better than anything else at that magnification. The only exception I found was an enlarging lens, the 4"/5.6 Enlarging Pro Raptar. It came out roughly equal to a known good 100/6.3 Luminar from 1:4 to 4:1, both lenses wide open. Stopping down made them worse. If nothing else, process lenses are handicapped by their small maximum apertures. I've tried only one process lens seriously around 1:1, a 55/8 Repro Claron, and the comparable real macro lenses I tried were visibly better.
I haven't had the chance to play with Rodenstock's, Nikon's, or Leica's 100 mm +/- macro lenses so can't comment. I do know that shorter Macro Nikkors are better than the equivalent Luminar.
I also think that agonizing about image quality in the plane of best focus when shooting around 1:1 is silly. Regardless of the lens used here's not enough, and there isn't enough depth of field either.
Cheers,
Dan