Process Lens & Close Work
I read where a process lens is optimized for 1:1 photography with a likely aperture setting of f22. At this magnification, the subject matter is about two focal lengths away from the lens.
I'm wondering, how many focal lengths away must be the subject matter, before a standard lens (versus a process lens) will get effectively the same result?
Put another way, at what magnification does a process lens become advantageous, versus a standard lens?
Re: Process Lens & Close Work
Depends. Better process lenses tend to be 4-element air-spaced symmetrical lenses versus the tessar style typically used for cheaper ones. So some of these, like my 4-element Apo Nikkors, are going to be very precise all the way from 1:1 clear out to infinity, and probably pretty good at even slightly greater magnification than 1:1, in other words, quite a bit better than general purpose photography lenses. And at least the series I work with is stunning sharp and well corrected by f/11 down. The f/22 standard is for sake of a printing industry common-denominator specifications, as does not condemn performance at other apertures.
Now, as per you actual question, there's no way to answer it, because you haven't told us yet exactly which "standard" shooting lenses you have in mind. They differ. Some of my own "standard" view lenses happen to be close-range corrected Fujinon A's and Schneider G-Clarons, which themselves perform excellently at infinity clear down to near-macro, at least stopped down a bit. But most general purpose LF lenses don't do so well really close up. And some, like the Nikkor AM series, are designed for only close-up.
Re: Process Lens & Close Work
The lens designer/manufacturer may have a recommendation on this. For example, Schneider-Kreuznach recommends that its 150mm Super-Symmar XL not be used at a magnification ratio of more than 3:1. For greater magnification, it would recommend a macro lens. As you probably know, there have been many discussions on the forum about whether macro lenses have advantages over process and standard lenses. In my case, I would follow the recommendation and use Nikon's Nikkor 210mm AM ED Macro lens instead of the 150mm Super-Symmar XL. It isn't relevant to your post, but this would also buy me a bit more working room.
Re: Process Lens & Close Work
Quote:
Originally Posted by
neil poulsen
I read where a process lens is optimized for 1:1 photography with a likely aperture setting of f22. At this magnification, the subject matter is about two focal lengths away from the lens.
I'm wondering, how many focal lengths away must be the subject matter, before a standard lens (versus a process lens) will get effectively the same result?
The same.
Quote:
Put another way, at what magnification does a process lens become advantageous, versus a standard lens?
This is an entirely different question. It depends on the "standard lens." There is no broadly applicable rule of thumb.
Drew, tessar type Apo-Nikkors have exactly as many elements as dialyte type Apo-Nikkors. I don't know whether the tessar types do as well at distance as the dialyte types do, never had any. I have, though, three TTH process tessar types, one badged Apotal, one badged "Cooke Copying Lens" and one engraved "Copying." All are, contrary to expectation, pretty good at all distances.
Re: Process Lens & Close Work
Dan - it's not the number of elements which counts, but the configuration and underlying application. 4-element process lenses are SYMMETRICAL. Budget style process lenses like for "Stat" copy cameras, were generally not. There are of course exceptions, like the very expensive Apo El Nikkor series - too expensive for any typical commercial copy application! But even regular Apo Nikkors were quite expensive when new. Now they're a bargain on the used market. But cheap lenses like Rogonars, once bundled with stat cameras under Beseler private labeling, are now sometimes sold as discount "student grade" enlarging lenses. Some of these are only 3-element.
But again, we don't yet know in this case the exact intended application. Taking close up pictures of flowers? - or of the eye of some insect on a petal of that flower?
Re: Process Lens & Close Work
Drew, not to quarrel too much, but tessar type process lenses have 4 elements and are quite asymmetric. I agree with you completely that dialyte type process lenses such as Apo-Artars, dialyte type Apo-Nikkors and Apo Ronars have 4 elements, are symmetrical and are very good at all distances. That they didn't drive tessar types from the market suggests that they were pretty good. I'm thinking of CZJ Apo-Tessars, which were eventually replaced by Germinars, and TTH Apotals. These were made in focal lengths more than slightly too long for "stat" cameras.
Re: Process Lens & Close Work
How on earth can any tessar formula be classified as symmetrical? The front group and rear group don't match! Note that I'm not criticizing older non-dialyte process lenses. I have a superb old single coated Zeiss f/9 apo tessar process lens that I love for its out of focus "bokeh" rendition. It does great at infinity too. But it's certainly neither as versatile nor precise as the more expensive later Apo Nikkors. And that distinction becomes critical when moving from general photography applications to downright nitpicky ones, like making precise enlarged internegs or interpositives in the lab.
Or, for a person I know who uses Apo Nikkor dialytes for extreme telephotography using small SLR cameras, it's also an important distinction. I don't use these for general photography myself because I'd need to put them in shutter, and that would compromise the overall weight and practicality of them. But I do have them on Sinar boards for sake of visual comparisons using a view camera, as well as for sake of enlarging application on a big enlarger of mine which accepts Sinar boards.
But as far as branding, that's a whole different game. Sometimes lens names get re-attached over time to relatively unrelated configurations. It's no different in industrial optics. But those CZJ Apo Tessars were not symmetrical; they were tessars. Apo Germinars were symmetrical, but by the same token, were NOT tessars.
They probably also cost way way more than the Apo Tessar option.
Re: Process Lens & Close Work
In my experience process lenses excel when the subject is flat, as in copy work, or using them for enlarging. For a picture with a central object with, perhaps, a blurry background, a conventional lens works very well for me at close distances.
Re: Process Lens & Close Work
Quote:
Originally Posted by
Drew Wiley
How on earth can any tessar formula be classified as symmetrical?
I think we agree on something. Please read the first sentence of post #6 above.
Re: Process Lens & Close Work
Quote:
Originally Posted by
Drew Wiley
. . . Now, as per you actual question, there's no way to answer it, because you haven't told us yet exactly which "standard" shooting lenses you have in mind. They differ. . . .
That's a good point. :o
While I would consider something else, I was thinking of a 210mm G-Claron as a process lens, and definitely a Plasmat (the only other lenses that I have) in the same focal length as a "standard" lens.
I have it in mind to photograph a violin in vertical, frontal position, straight on and across using a 5x7 camera with no movements. I would enlarge either to 11x14 or 16x20. I would like to see every tiny spec of detail on the front of the violin.