Any large format lenses with floating elements?

[engl]

Just out of curiosity, are there any large format lenses with floating elements?

[Bob Salomon]

No, that would require a focusing mount. There are lenses that can be re-optimized by switching the front and rear groups. An example would be the discontinued Rodenstock 210 and 300mm Makro Sironar lenses. With the front and rear groups in the normal position (that is the way the lenses came out of the box when new) the lenses are corrected for 1:3 to 1:1 ratios. By swithching the front and rear groups the lenses are optimized from 1:1 to 3:1. Diagrams on the front and rear groups on the lenses themselves showed which set-up to use for which ratios.

Regular lenses are usually optimized or either 1:10 or 1:20 so a floating element wouldn't help them very much.

[cdholden]

Are you talking about "floating" with respect to the plane of focus (i.e. anything in a helicoil mount) or a lens with an element/group that moves while other elements/groups in the lens remain static?

[ic-racer]

Velostigmat Series II

[Jim Galli]

...

[Bob Salomon]

Yes! The Cooke portrait lenses and the Voigtlander Universal Heliar all have floating elements that change the diffusion. Many of the early petzval's employed Dallmeyer's patent for a floating element that added diffusion, and I suppose even the Velostigmat with diffusion qualifies.

Most, if not all, modern lenses with a floating element have it to reoptimize the lens to correct for different image ratios. Variable soft focus, or diffusion, is not what most call a floating element.

[engl]

Are you talking about "floating" with respect to the plane of focus (i.e. anything in a helicoil mount) or a lens with an element/group that moves while other elements/groups in the lens remain static?

I was referring to lenses with elements/groups moving relative to the other elements/groups of the lens.

Bob, thanks for the reply. That does in some sense work like floating elements, but it is a tad labor intensive :)

But I do not agree that a focusing mount is needed. The reason I asked this question was that I'd been looking at the Mamiya RB67. This camera uses bellows focusing, but still has a number of lenses with floating elements. There is a helicoid on the lens controlling the floating elements, used to set the distance for which to optimize performance. Focusing still has to be done using the bellows.

The feature of course integrates more smoothly with lenses with helicoid focusing, as they can automatically set the floating elements at the optimal setting. Many lenses for 135-format as well as some medium format lenses do this. It is especially useful for macro lenses and retrofocus wides, but also found on non-retrofocus non-wides.

Edit: just a side note about the RB67 lenses with floating elements, the distance setting ring also cleverly works as a DOF scale, although you'd want a bed/rail distance scale for it to be accurate on a LF camera.

[cdholden]

I was referring to lenses with elements/groups moving relative to the other elements/groups of the lens.


In addition to the lenses above, add the Wollensak Vitax to your list.

[vinny]

I dropped a 210 repromaster in Convict Lake one october. It didn't float and took two of us to retrieve it with some ski poles. Still good as new.

[cdholden]

Velostigmat Series II

If I remember correctly, the only Series II Velostigmats with the diffusion control are the ones with focal length of 9.5" and longer. The smaller ones don't offer it.

[engl]

Thanks for the information about floating elements for the purpose of diffusion in some lenses. Like Bob, I had sharpness and flatness of field optimization in mind when I thought about floating elements, but apparently there are more uses.

Come to think of it, if I ever sell my Moskva-2 6x9 folder, maybe I could label the front cell focusing lens as having "floating elements"... :)

[engl]

I dropped a 210 repromaster in Convict Lake one october. It didn't float and took two of us to retrieve it with some ski poles. Still good as new.

We could start a collaboration here on the forum to test all lenses for floating elements in this manner, I remember reading about a few posters having done their part already.

[Mark Sawyer]

Most, if not all, modern lenses with a floating element have it to reoptimize the lens to correct for different image ratios. Variable soft focus, or diffusion, is not what most call a floating element.

I'm not sure what you mean by "different image ratios", Bob. Are you talking about variable focal length ("zoom") lenses?

[Bob Salomon]

I'm not sure what you mean by "different image ratios", Bob. Are you talking about variable focal length ("zoom") lenses?

magnification ratios.

[Mark Sawyer]

Thanks, Bob, I somehow missed your first post (#2). I've never seen such a design in a macro lens, so I stand enlightened!

To the list of floating-for-diffusion lenses, I'll add the Portrait Unar, and Ilex and Conley imitations of the Vitax and Velostigmat Series II.

And there's the Dallmeyer Adon, but that's a whole 'nother category...

[Helen Bach]

The Caldwell Photographic 120mm f/4.5 Macro UV-IR Apochromat has floating elements.
www.caldwell-photographic.com/20100819_120Brochure.pdf

(As well as the RB67, the Rollei SL66 has lenses with floating elements that you set the distance on independently of the focussing.)

Best,
Helen

[engl]

Thanks for the reply Helen, what a remarkable lens. It does not appear to be a large format lens (unless only used near 1:1, which negates the floating elements benefit), but it shows that the type of lens I had in mind exists.

Considering it is a UV-VIS-IR apochromat, 6 UD elements and an aspheric one, with MTF charts that look more impressive than the digital lenses Rodenstock and Schneider offer, I'm guessing the price is going to be pretty remarkable too :)