Imagon 300mm

[mylek]

Hello,

with the Imagon 300mm lens, there is 2 versions according to the shutter used and i'm wondering if the 5,8-7,7 grid is really useful.
What i will be losing without it?
Will a 250mm lens with a the 5,8-7,7 grid will be more useful on a 5x7 even if it isn't the proper format. I intend to use it for portraiture, half body to head & shoulder.

Regards!

[Mark Sawyer]

Using the h/stop ("grid") disks allows you to get one kind of soft effect, the "Imagon Effect", but using the conventional aperture in the shutter gives you a more conventional soft effect, similar to other achromatic meniscus lenses, like the Kodak Portrait Lens. The Imagon is very nice either way.

Imagons will illuminate a much larger frame than they are recommended for, (the 250mm will light up an 8x10 all the way into the corners and then some), but there are a couple of good reasons for recommending a longer one for portrait use. One is that a longer focal length gives a more pleasing perspective, (shorter focal lengths up close can make the nose look larger and the face a bit bulbous). Another is that while the corners are illuminated, they can be very, very soft, which may or may not work in a particular portrait.

Rodenstock has very specific recommendation for "how to use the Imagon", and there's sound reasoning behind their advice. But as with many lenses, and soft lenses especially, an experienced user can bend or break the rules and get fine results. I've done portraits with the 300mm on 8x10, and expect the 250mm would be fine on 5x7.

[jp]

The grid/strainer will allow you to reduce the amount of light hitting the film without drastically changing diffusion. Most soft lenses, stopping down reduces the desirable diffusion. Usually in normal lenses, sharpness, depth of field, and exposure are tightly controlled by the aperture. SF by itself alters DOF with it's layering of focii as inner rays focus different than outer rays (with respect to the radius of the lens). Imagon grid/strainer further alters that relationship by allowing less light but still a mix of inner and outer rays for reasonable diffusion and depth of field. If you are indoors or low outdoor light, using it without a disc makes it a perfectly good soft focus lens that will provide good results by varying the shutter's aperture, just not in the manner it's designers intended, but there are many ways to skin that cat.

[Bob Salomon]

The grid/strainer will allow you to reduce the amount of light hitting the film without drastically changing diffusion. Most soft lenses, stopping down reduces the desirable diffusion. Usually in normal lenses, sharpness, depth of field, and exposure are tightly controlled by the aperture. SF by itself alters DOF with it's layering of focii as inner rays focus different than outer rays (with respect to the radius of the lens). Imagon grid/strainer further alters that relationship by allowing less light but still a mix of inner and outer rays for reasonable diffusion and depth of field. If you are indoors or low outdoor light, using it without a disc makes it a perfectly good soft focus lens that will provide good results by varying the shutter's aperture, just not in the manner it's designers intended, but there are many ways to skin that cat.

No, The disks do control the degree of sharpness and halation with the Imagon. The smaller the opening in the disk the sharper the image will be. With the disk with the smallest hole, with all of the surrounding holes rotated closed, the Imagon is quite sharp.
With no disk it is at its greatest degree of halation. With the disk with the largest hole with the surrounding holes open it would be less halation and less softness. If you close those holes it loses halation and becomes sharper again. Using the next smaller disk with all holes open it will be the same H stop as the larger disk with the surrounding holes closed but will have less halation again and will be sharper. Closing those surrounding holes will give the least halation and sharpest results.
Note: We are talking about the 300mm here and the modern versions of the 300mm came with only two disks as the opening in the number three shutter was too small to allow the lens to be used at its fastest H settings. The 250mm, 200mm, 120mm and 180mm all came with 3 disks.
So the modern 300mm did not reach 5.8 as its fastest speed and since the 3 shutter has an opening of about 40mm its fastest speed is 6.8.

Note: To obtain the full Imagon effect you should be using a contrast ratio of 5:1 rather then 3:1 and not use umbrellas but instead use elliptical type reflectors when using artificial light.

Note: The reason that Rodenstock recommends that the aperture blades in the shutter not be used is because the Imagon is designed so that the central part of the lens casts the main image onto the image plane and the surrounding holes cast a secondary image over the central image. The amount of secondary image cast is controoled by the opening of the peripheral rays. The more the holes are open the more halation will be cast.
If the aperture blades in the shutter are used the control of those peripheral rays is lost and the Imagon will not then have its characteristic halation effect.

Note: The amount of halation varies with the focal length of the lens with any given H stop. So the focal length recommended by Rodenstock is to ensure that the effect at say 7.7 with the disk with the surrounding holes open, at a desired print size, will be the same with any of the focal lengths at the magnification required on each format to reach that print size. So the 200mm is recommended for negatives up to 9x12cm. The 250mm for up to 4x5 and the 300 of up to 5x7.

[Mark Sawyer]

Note: To obtain the full Imagon effect you should be using a contrast ratio of 5:1 rather then 3:1 and not use umbrellas but instead use elliptical type reflectors when using artificial light...

Bob, in your experience, should photographers use the little elliptical dish built into most strobe housing units, or add a larger elliptical reflector to the strobe?

And a side note that with this sort of lighting, one must keep an eye out for the dreaded "Kuhn bugs".

[Bob Salomon]

Bob, in your experience, should photographers use the little elliptical dish built into most strobe housing units, or add a larger elliptical reflector to the strobe?

And a side note that with this sort of lighting, one must keep an eye out for the dreaded "Kuhn bugs".

The dish works just fine. Look for Monte Zucker "one light portraits" taken with a single light (many with a Rollei E250 moonlight) and a silver reflector. He did those with the 200mm Imagon for the ones with the halation on Hasselblad and Rollei 6008 cameras. You can also look for Tibor Horvath portraitures. He also did similar work with the 200mm Imagon on a Hasselbld with Broncolor moonlights also equipped with the portrait reflectors with the diffusion disk.

While they were alive I got to work with both of them. 23 Zucker seminars in one year while I was with Rollei and almost the same number one year with Tibor when I was with EPOI and represented Broncolor. It was quite a learning experience.

While both were fantastic photographers and both knew how to pass their knowledge on to the attendees and how to successfully sell their work to the public both tended to downplay their depth of photographic technical knowledge. And for them it really worked!

[mylek]

Thanks everybody!

Lots of information to digest before i make a move but i think i'll go with the 300m even if it a new one with the 7,7 grid.
If i understand well, i will loose only the possibility to make softer picture.
From your knowledge, did people use the old Imagon with the 5,8 grid more often than with the 7,7?

[Bob Salomon]

Thanks everybody!

Lots of information to digest before i make a move but i think i'll go with the 300m even if it a new one with the 7,7 grid.
If i understand well, i will loose only the possibility to make softer picture.
From your knowledge, did people use the old Imagon with the 5,8 grid more often than with the 7,7?

The versions with the third disk are so old that I have no experience with them. But I am only 73!

My experience with the 120 through the 250 was that most portrait photographers were at 7.7 so that would be the largest disk for the 300 and the middle disk for the 120 to 250mm wide open.

[Mark Sawyer]

A big thanks for the excellent information, Bob!

[Tin Can]

Yes, thank you Bob Salomon.

Really informative Imagon information, that I could not find anywhere.

I do wonder why the Imagon is the orphan child of soft focus lenses. I know CC Harrison addressed that with his opinion, but I see few big Imagon for sale. I seek one.

[Mark Sawyer]

I've used Imagons of various focal lengths, and agree that they are wonderful and very under-appreciated, especially as they're one of the few (very few in longer focal lengths) coated soft lenses made. I'd speculate that the discs confuse a lot of people, making them currently less popular. They were made for a longer stretch of time than most lenses of any type, and there seem to be enough of them available to suggest they were popular in the past, just not today.