View Full Version : Regular and Soft-focus lenses at wide and narrow apertures

21-Feb-2004, 18:06
What is the difference between a soft focus lens and a regular lens wide open or close to it?

What is the difference stopped down, recognizing that soft focus lenses, except for the Cooke, have been out of production for a long time?

I'm particularly interested in these questions in relation to the Wollensak Veritar 10"/250mm f6 as compared to a modern Rodenstock, Schneider, Nikon or Fuji of similar focal length.

If anyone knows of photographs on the internet that demonstrate the difference, I'd be most intererested in links.


21-Feb-2004, 18:24
The Veritar is based on the Pinkham and Smith design (according to Kingslake), as is the new Cooke lens. Check out the pictures on the Cooke site and you will have a pretty good idea of how the Veritar looks wide open. There is a kind of diffuse glowing effect, and loss of contrast that you don't see in a normal lens. Also, the plane of focus is quite sharply defined, and extends only behind the plane of focus, not in front as in a normal lens.

Ernest Purdum
21-Feb-2004, 18:54
A good modern lens wide open will still be fairly sharp as compared to a soft focus lens. As you stop down, several aberrations, including the spherical, which is the aberration usually responsible for the soft focus characteristics, diminish. At very small apertures it may become difficult to tell that sssa soft focus lens was used.

Besides the Cooke, there have been several other soft focus lenses made in recent years, principally the Rodenstock Imagon.

Images on the internet are limited in their ability to show the subtle differences between different lens usage. You really need to see actual prints to appreciate the effects.

If you go back to the home page and scroll down to the lists of articles, you'll find an article on soft focus lenses which you may find useful.

David A. Goldfarb
21-Feb-2004, 19:00
Each lens is a little different. I have a few classic lenses of different types and similar focal lengths, so I'm thinking I might take a few controlled comparison shots and post the results on the web when I get some time. In theory lenses should become more similar as they are stopped down, but they can still have their own local contrast effects. I find the Verito, for instance, to be very smooth even at small apertures, even though the "soft focus" effect is mostly apparent between wide open and f:8.

Here's a sample image with the Verito at f:22--


and here's a detail showing the halation that occurs even at that aperture--


21-Feb-2004, 19:17

from the "instructions" that come with a veritar lens:

"a veritar negative renders a delightful atmospheric quality of softness ... beautfully blends the highlights, halftones, and shadows and supresses unessential wiry detail. in most cases excessive amount of retouching is eleminated || the veritar les is of three element construction, free from distortion and corrected for color. the blending of tones or soft focus effect in the veritar is obtained by controlled spherical aberrations. some soft focus lenses accomplish this effect by chromatic aberration, and therefore are not suitable for color. the ground glass image o fthese lenses is visually sharp but out of focus on the negatives. the soft focus effect also changes with the different types of film used. with the veritar lens there is no change in focus whether you shoot color or black and white film and the image appears on the negative as seen on the ground glass. || varous degrees of softness or diffusion are controlled by moving the diaphragm. at wide aperature the soft focus effect is most pronounced and decreases gradually as the lens is stopped down. at the smaller aperatures the lens appreaches the performance of an anastigmat type lens. "

i have a 10" and have used for color and black and white portraits. it is a really nice lens opened up. i never really use it stopped down, so i can't really comment on that.

its kind of tricky to focus with it, you have to stop down to f8, focus on the tip of the nose instead of the eyes ( because of the plane of focus phil glass mentioned) ... and then open it up.

21-Feb-2004, 20:51

I can't address the Veritar directly. However, I do have some experience with the Verito. Last summer I did a very unscientific comparison across the aperture range of an 8 3/4" Verito. The smoothness to which David alludes was apparent at all settings (at least in the original prints). However, the change in softness is dramatic. You can see the photos on my site at http://wfwhitaker.com/verito.htm.

As mentioned, portrait lenses suffered from uncorrected aberrations, spherical being the most popular, which was pronounced at wide apertures, but diminished at smaller apertures. "Commercial" lenses were designed to be sharp across the aperture range. The "halation" effect in David's detail photo of the cacti bespeaks chromatic aberration, unless I'm mistaken. And that particular aberration would not tend to diminish as much as the lens is stopped down. Hence, it's still apparent at f/22, as noted. That very bright, fine detail against a dark background is quite demanding of a lens. But then, as the above post notes, the early portrait lenses weren't designed to be used with color film. (When did color film first become available?...) The materials early on were typically orthochromatic which would've reduced the effects of chromatic aberration.


David A. Goldfarb
21-Feb-2004, 21:37
I think that's right, William. The color fringing associated with chromatic aberration is pretty clear in that detail. There is probably some spherical aberration too, which would decrease as the lens is stopped down, but it looks like enough of a "glow" that it's probably still detectable even at f:22.

Richard Årlin
22-Feb-2004, 05:08
I have a 240 mm Dagor that I use with a 8x10, I have not tested it wide open on my 4x5 but I have been thinking it may possibly be interesting... has anyone tried it? I suppose it would be somewhat different from a modern lens.

David A. Goldfarb
22-Feb-2004, 07:38

A Dagor is not a soft lens, but it does have a pretty smooth look at wider apertures. The above image was made with a 12"/6.8 Gold Dot Dagor around f:14 on 8x10" Astia. Lighting was fairly simple and relatively soft--main light in a large umbrella plus the background light and no fill or accent lights.

Stopped down and with hard lighting a Dagor can look pretty "clinical." This shot, made with the same lens between f:32 and f:45 looks okay on the web:


But if you see a contact print, her skin, which is not too bad in real life, looks like the Martian landscape. Here's a detail:


22-Feb-2004, 12:00

In all my earlier yammering, your question got kind of lost.

"What is the difference between a soft focus lens and a regular lens wide open or close to it?"

In principle a soft focus lens will be a lot softer than a "regular" lens wide open, assuming the same aperture for each. "Regular" could mean either a modern lens or a vintage commercial lens. It remains a truism that most lenses tend not to be their sharpest at their widest apertures. However, you will almost certainly not be able to duplicate a true soft focus effect by using a "regular" lens wide open.

As for comparing them stopped down, it's generally true that most lenses are sharper when stopped down. But expect the results to vary. There's more to an image than just sharpness and in the end it really depends on your personal preferences.

Each lens formula has its own personality. That's part of the attraction (read: addiction) that some of us find in vintage lenses. Go out and make some comparisons yourself. You'll find it both fun and educational.


22-Feb-2004, 14:25
Thanks all. The reponses and links were very helpful.