Rodenstock Imagon 300 mm

[Joe Gauthier]

I recently acquired a Rodenstock Imagon 300 mm lens and was wondering: Has anyone had experience using studio lighting with this lens?

Since it doesn't have f stops per se, but rather, has lens overlays with holes with h ranges in order to soften the edges outside the center area of the lens, are the h ranges roughly equivalent to f stops?

Would it be best to use this lens in the M setting for manual when wanting to sync with studio lighting? The sync cord attaches perfectly to the lens but I suspect this is how flash bulbs were attached in the 1930s and 1940s.

Is there anyway to find out how old the lens might be?

Thanks for your help. Joe Gauthier

[Peter K]

The Imagon was mounted in Compound shutters. This shutters are equipped with a X-synchro contact. So the Imagon works perfectly with studio flashlight.

More info about this lens you can find here http://www.cameraeccentric.com/html/info/imagon_1.html.

[Bob Salomon]

What is the serial number?

[Bjorn Nilsson]

There's a lot of info on cameraeccentric which is linked above. (I think they have at least two articles on the Imagon.
One thing about studio lightning though. Most sources advice to use rather harsh and direct lighning. Then experiment with the discs to soften things up. If you set the light with e.g. big bouncers which is fine with normal lenses you will get very flat results with the Imagon and a softening disc.

//Björn

[Joe Gauthier]

Thank you all for responding so quickly. This lens holds a great deal of fascination for me and I´m grateful for your help.

The lens serial number is 4280936 printed on the front barrel in about the same size font as Rodenstock.

The other number printed much smaller is 787098 and is located on the largest diameter of the housing holding the lens close to the cocking mechanism.

The lens has an M setting, a B setting and a T setting. I am unable to find an X setting.

I read somewhere that a journal of photographic optics had a sub chapter on this and other soft focus lenses, but I haven´t been able to locate it yet.

[Peter K]

The smaller number is the serial number of the shutter.

There is no setting for the synchronisation, the compound is always X-synchronisized.

If I'm working with the Imagon, at first I focus with the small holes closed and than the holes will be opend carefully up to the point the image looks fine. If the h-stop is to big, you can take the 4x - gray-filter to reduce the brightness.

Have fun

Peter K

[Bob Salomon]

4280936

That is a lens made between 1954 and 1957. Closer to 1957

[Bob Salomon]

The smaller number is the serial number of the shutter.

There is no setting for the synchronisation, the compound is always X-synchronisized.

If I'm working with the Imagon, at first I focus with the small holes closed and than the holes will be opend carefully up to the point the image looks fine. If the h-stop is to big, you can take the 4x - gray-filter to reduce the brightness.

Have fun

Peter K

The focus will shift when you open and close the holes or change the disks. Focusing should always be done at the setting that you will actually use.

[Peter K]

The focus will shift when you open and close the holes or change the disks. Focusing should always be done at the setting that you will actually use.
Sorry Bob that's wrong. Here is the text from the operating instructions

"Wenn Sie mit dem IMAGON arbeiten, sollten Sie die Schärfe zunächst mit völlig geschlossenen Sieblöchern einstellen, Das erleichtert die Fokussierung und die Beurteilung der Tiefenschärfe. Jetzt können Sie die Löcher bis zu dem gewünschten Überstrahlungsgrad öffnen."

It says the same I've written before. You can find the same here http://www.cameraeccentric.com/html/info/imagon_1.html

And at least I've tried it once more with my Imagon 360mm five minutes ago :p

The special thing of Staeble's Imagon is the focal plane doesn't change like with other soft-focus lenses as with the Universal-Heliar. But the deepth of field seems to increase if the outer part of the Imagon will be used by opening the small holes.

Peter K

[Bob Salomon]

Sorry Bob that's wrong. Here is the text from the operating instructions

"Wenn Sie mit dem IMAGON arbeiten, sollten Sie die Schärfe zunächst mit völlig geschlossenen Sieblöchern einstellen, Das erleichtert die Fokussierung und die Beurteilung der Tiefenschärfe. Jetzt können Sie die Löcher bis zu dem gewünschten Überstrahlungsgrad öffnen."

It says the same I've written before. You can find the same here http://www.cameraeccentric.com/html/info/imagon_1.html

And at least I've tried it once more with my Imagon 360mm five minutes ago :p

The special thing of Staeble's Imagon is the focal plane doesn't change like with other soft-focus lenses as with the Universal-Heliar. But the deepth of field seems to increase if the outer part of the Imagon will be used by opening the small holes.

Peter K

Then I will quote the instruction book that was packed with the lens by the factory. Page 8 in English:

".....At the same time the plane of sharpest focus shifts. The object on which a lens with spherical aberration is focused at full aperture is no longer in the plane of sharpest focus of the stopped-down lens. HENCE THE RODENSTOCK IMAGON MUST ALWAYS BE FOCUSED AT THE APERTURE AT WHICH IT IS TO BE USED." (emphasis is mine).

It appears that the instructions provided by Dr. Staeble are different then Rodenstock's. Rodenstock began manufacturing the Imagon in 1931 so, provided nothing in the optical formula has changed I would suggest following the factory's recommendation.

[Peter K]

My quotations where from Rodenstock brochures, packed with the lenses by the factory. With my two Imagons, 300mm and 360mm, made by Rodenstock. But the easiest way is to look at the ground-glass. Of course when the Imagon is used without a sieve or used with the diapragm build in the shutter, the focus shifts when the diaphragm will be closed from wide-open to closed. Also the Imagon is chromatic corrected so there is no "chemical focus-shift".

But the Imagon's special flair cannot be described, only seen on the ground-glass or the images.

[Bob Salomon]

My quotations where from Rodenstock brochures, packed with the lenses by the factory. With my two Imagons, 300mm and 360mm, made by Rodenstock. But the easiest way is to look at the ground-glass. Of course when the Imagon is used without a sieve or used with the diapragm build in the shutter, the focus shifts when the diaphragm will be closed from wide-open to closed. Also the Imagon is chromatic corrected so there is no "chemical focus-shift".

But the Imagon's special flair cannot be described, only seen on the ground-glass or the images.

Peter,

My quote was from the instruction book packed with the lenses from April 1986 untill the lenses were discontinued.

[Armin Seeholzer]

"".....At the same time the plane of sharpest focus shifts. The object on which a lens with spherical aberration is focused at full aperture is no longer in the plane of sharpest focus of the stopped-down lens. HENCE THE RODENSTOCK IMAGON MUST ALWAYS BE FOCUSED AT THE APERTURE AT WHICH IT IS TO BE USED." (emphasis is mine)."

Bob you don't get it right here!
Peter has the correct idea of it and he does use it the right way and you do misunderstand him!
He use the same disc for the fokusing but he used it only with the small holes closed for the focusing part and then open them up on the same disc till he gets the effect he wants!
I have the same Rodenstock instructions and use it also exatly like Peter does!
Maybe the translation is not so good, but it is as Peter told you in german written!!!!

Cheers Armin

[Bob Salomon]

Armin,

Thanks but I can only by what the factory published since 1986. That is also what the factory told us whenever we asked.

In the instruction book published and supplied with the lens since 1986 the instructions are given in German as well as English, Japanese, Korean, French and Italian.

In English on both page 8 - describing the optical characteristics of the Imagon and on page 10 - taking technique - the instructions call for the lens to be focused at the intended aperture.

Page 10 also then counterdicts itself by stating:
" Always determine the zone of relative sharpness with the marginal diaphragm apertures fully closed. ..... Although opening the marginal apertures slightly alters the focal length, this is negligible."

So in one case they say always focus at the shooting aperture and on the other hand they say not to because:

"the ground glass screen image is too vague and gives you little idea of the detail rendering".

So if it works for you - do it.

[Peter K]

So what? During sixty years Staeble and Rodenstock writes one has to focus in this way and without changing the lens-design the operating instructions will be changed. It looks like an optic engeneer without practice in photography has written a new brochure.

[Armin Seeholzer]

I know by myself the instruction is a bit fuzzi and foggi as the pictures are sometimes also;--))))
And Bob don't miss its a Tiefenbildner a DOF expander, so it should not be thad critical anyway!
I just used mine now for two 8x10 flower pictures!
Cheers Armin

[Dave_B]

As long as we are all exposing our ignorance about this lens, I will expose mine as well. Why do they go to the trouble of using H instead of aperture when as far as correct exposure is concerned they seem to be the same? Why label the disks as H? Is it because the H number gives the same exposure as the f stop but not the same depth of field?

The lens comes with a two stop neutral density filter. I assume that one can focus without the filter and then use it to get the correct shutter speed without having to refocus. Is this correct? Inquiring minds want to know.

Cheers,
Dave b.

[Armin Seeholzer]

double post!

[Armin Seeholzer]

Yes Dave the use of the filter is correct, you ned it with strobes which are to strong sometimes and outside with the sun. Otherwise you could not use it open outside in the sun.
And they call it H for Halo effect which you get out of it!
And maybe not f stop because you should anyway a bit overexpose it around 1 f stop to get the Imagon look!
Have fun, Armin

[Armin Seeholzer]

Sorry just two times the same!

[Peter K]

Why label the disks as H? Is it because the H number gives the same exposure as the f stop but not the same depth of field?
The f-stop is the relation of the geometrical area of the entrance pupil of a lens to it's focal-lenght. This area is normaly circular or polygonal. But the special diaphragm of the Imagon, also the disks of the Leitz Thambar, cannot measured in this way. So Staeble, the inventor of the Imagon, took a new value, the H-stop. H from "Helligkeit" = brightness. Of course this value is not exact in a geometrical way but together with the exposure latitude of the photographic plate it gives a value one can work with. Of course one could use the T-value, transmission-value, as used with movie lenses, but this would need a scale on the sieve disks, an expenditure without any practical value.

BTW depth of field is nothing else as an illusion. Every lens has only a certain focus distance. But with the Imagon this illusion will be used to get realy special images.

Peter K

[Dave_B]

Armin, Peter:
Thanks,
Dave B.

[Armin Seeholzer]

Yes Peter is right with "Helligkeit", he is the german lens guru I'm not! ;--)))

Chers Armin