Question for soft focus lens gurus

[Alex Wei]

I got a Wolly soft focus lens (12" Velostigmat II) lately and have been playing around with it for a while. I took the front cell out, release the screw that hold the cell for only 1 full turns so that I can go for even greater softness. I shot several images with the soft focus setting way passed the #5 set on the lens (about two full revolutions. Learned this from other thread :) ) and I like the results. It gives me a soft image with a little bit of "glow"= halo? compare to the #5 setting on the lens. The way I took the image is set the SF setting first, focus and then take the image.

My question is compare to other similar SF lenses like Cooke portrait lens or Universal Heliar lens, the SF setting on the Wolly Velostigmat turns more than the others. It only a quarter of whole turn before it reach the max soft setting on the Cooke or Heliar lens, but it took a full revolution to get the softness setting on the Velosigmat.

Can any one tell me why the Velosigmat needs to turn more than the Cooke or Heliar? Is it my way of using the lens the right way? Because I know some photographer didn't refocus after set the soft focus on the Velostigmat. They focus first with the sharpest setting, then apply the softness.

Thanks,

Alex W.

[Mark Sawyer]

The Velostigmat is a tessar with a moving front element, while the Cooke and Universal Heliar are triplets with a moving internal element, so the design is quite different. Also, the Velostigmat's threads are quite fine, so one revolution is much less movement than on the other lenses.

My experience with the Velostigmat is that it shifts focal length slightly as you adjust the diffusion, and if you don't refocus, it's just fuzzy. And as you've found, the factory diffusion settings don't go far enough to give an appreciable soft focus effect.

[Alex Wei]

Thanks, Mark, that explains a lot.

Will do more test, so far I like the look of wide open with soft focus set at '10'.

Alex

[Jim Galli]

The Cooke knuckler ring actually turns a helical that moves the elements a great distance compared to the Wolly. Did you see the page where I did the same thing to a Bausch & Lomb lens. People are paying nutty prices for the Velo's all of a sudden.

[Alex Wei]

Jim, thanks for the answer. Of course the velostigmat price is going higher because of the little comparison you did :)

Mark, if I recall correctly, you also tried to loose the front cell pass the limit, have you managed to do so?

when I try to have a greater DOF, like using F8, I find even SF #10 is not enough, I will try to twist it even further until the lens falls off :)

Alex

[Mark Sawyer]

Mark, if I recall correctly, you also tried to loose the front cell pass the limit, have you managed to do so?


Yup, and I found the "best" spot was with the threads screwed in just enough to keep the front element from falling off. Jim's thread on the B&L Tessar really shows what moving the front element can do.

Here's another thread you should look at:

http://www.largeformatphotography.info/forum/showthread.php?t=29047&highlight=Velostigmat