Optimum Range: Goerz 14" Red Dot Artar

[neil poulsen]

What's the optimum range of a Goerz Red Dot Artar 14" lens? These lenses are known to be excellent at closer distances. But, how close?

Put another way, at what distance do images from an RD Artar 14" lens show little difference from those photographed with a standard 360mm Plasmat from any of the big four?

[Vaughn]

I believe the lens spacing comes into play here. The non-red dot variety were more process-camera orientated and spaced to optimize bigger enlargements. I have only used the Red Dot variety (19" and 24").

This chart gives numbers for using the 14" RD Artar for a 1:1 (lifesize) reproduction...(28" from lens to subject)

https://www.pacificrimcamera.com/rl/00268/00268.pdf

[Bernice Loui]

On paper the barrel versions are "set" ala optimized for 1:1 life-size, shutter version are optimized for near infinity focus. In real world image making barrel or shutter makes little difference from 1:1 to infinity. This example of the 14" APO artar previously posted was made using a barrel version. Having used both barrel and shutter versions of APO artar over the decades, the optical performance difference on film is nil...
https://www.largeformatphotography.i...420-microscope

To this day, the barrel versions are preferred to shutter versions due to the nice round iris (into out of focus rendition and ..) and Sinar shutter which negated shutter problems and results in consistent shutter speeds.

The modern Plasmat has a larger image circle compared to the APO artar, in all other aspects of optical performance the APO artar (red dot) IS better at all reproduction ratio long as the APO artar is used within it's spec image circle and from f16 to f32.. or why these remain the far preferred for longer than normal focal lenght lenses with a exposure aperture of f11/f16 to f45 (rarely used). Have a set of these in barrel on Sinar lens boards from 4" to 24". APO artar is essentially interchangeable with APO ronar or APO nikkor (not the early Tessar version). These Dialyte formula lenses are smaller than the modern Plasmat for the same lens focal length, essentially f5.6 for the modern Plasmat -vs- f9 and smaller for the Dialyte, IMO a significant advantage in many ways.


Bernice

What's the optimum range of a Goerz Red Dot Artar 14" lens? These lenses are known to be excellent at closer distances. But, how close?

Put another way, at what distance do images from an RD Artar 14" lens show little difference from those photographed with a standard 360mm Plasmat from any of the big four?

[Bernice Loui]

Sinar F, 6" APO artar example, 4x5 Agfachrome RS100, "life size" 1:1, Epson 4990 scanner to digital file. Previously posted. Image made circa mid 1980's.



Cropped area:



Conditions:
~limits of Epson 4990 scanner to .jpg file.
~Limits of image quality due to posted images to LFF.
~Painted scene is on the inside of the frosted glass and the bottle is curved..

Regardless this offers some idea of optical performance of APO artar at 1:1. Be assured the original 4x5 color transparency is "painfully" sharp..



Bernice

[Mark Sampson]

I think the theory is that the Artar, being a symmetrical design, will perform well at both infinity and close-up focus. Certainly the only RD Artar I've ever used in both conditions, a 19", was quite sharp at any focus distance. However as those photos were made on the job, I can't post examples. But Bernice's fine image shows the lens' quality quite well.
If you were to make a careful comparison test, with identically exposed 4x5 chromes on a light table, you'll likely find that the modern plasmat lens produces a higher contrast image.
OTOH, Schneider offered the Artar well into the 1990s; I've never seen images from one of those, and it's possible that more modern lens coating would produce higher-contrast images than a 1950s Goerz example. Pure speculation on my part!

[ridax]

When I was more curious about sharpness and less lazy, I tested a 180mm and a 240mm Apo-Ronars at about 1:20. Those were in shutters but still their largest aberration was coma - just as with the vast majority of 1:1 optimized lenses. The farther from 1:1 and closer to infinity, the more prominent coma is. The smaller the aperture, the smaller coma becomes.

Plasmats suffer from other aberrations more then from their coma. So when comparing dialytes to plasmats at distances different from 1:1, the working aperture is even more impotant than the distance itself.

[Bernice Loui]

Having used single coated(APO artar, APO ronar, APO nikkor) and multi-coated(APO ronar) Dialyte formula lenses the different are in contrast and resistance to flare. As expected the multi-coated versions are higher contrast with more resistance to flare. This is neither better or worst as there are times when lower contrast is a GOOD thing and times when higher contrast is a bad thing.. It completely depends on the image goals. Have both varieties, they are used depending on image goals.

As for resistance to flare, a good and proper compendium lens shade can do wonders to make this better unless the subject is beyond extreme back lighted. This is where multi-coatings can and do make a difference.

Schneider made their version of the APO artar to the end of it's production, think early 2000's or no earlier than the later 1990's as they were still in the Schneider catalog back then. Never used one. APO ronar were multi coated in the Sinar versions then later in shutter versions..


Bernice

If you were to make a careful comparison test, with identically exposed 4x5 chromes on a light table, you'll likely find that the modern plasmat lens produces a higher contrast image.

OTOH, Schneider offered the Artar well into the 1990s; I've never seen images from one of those, and it's possible that more modern lens coating would produce higher-contrast images than a 1950s Goerz example. Pure speculation on my part!