How to focus a soft focus lens

[Geoffrey_1456]

Hi All,

I just purchased a Rodenstock Imagon 250/5.8 soft focus lens. While playing with it, I have not been able to get to a reasonable "sharpness" I would like to hav e. Could someone kindly offer me some tips on how to use a soft focus lens? Ma ny thanks!

[Bob Salomon]

Best to call us at 800 735 4373

But here are some tips:

1: use a 5:1 lighting ratio. 2: don't use umbrelaas 3: focus at the taking condition with the disk you want to use in place and set for the effect you want. there is a focus shift when you change disks. 4: To see what a properly focused image looks like place a halogen flashlight in the scene and focus on the lit bulb. When you see that the bulb forms a cross you are in focus. Then see what the image area that is in focus looks like.

5: You have at most settings a choice of 2 degrees of softness with the Imagon.

With no disk in place you have an exposure opening of 5.8 and maximum softness. With the disk with the largest opening in place with all holes open you are still at 5.8 but are sharper.

With that disk in the fully closed position or with the middle disk with all hol es open you are at 7.7. The first disk with all holes closed will be softer then the second disk with all holes open.

The second disk fully closed and the third disk fully open are the same opening but the third disk full open is sharper then the second disk fully closed.

With the third disk fully closed the Imagon becomes a sharp lens.

[david clark]

Hi Geoffrey, from my own experience, soft focus lenses are hard to catch onto. I don't have the Imagon. I have one that is the adustable variety and one that isn't. Mine are probably old portrait lenses that I use for landscape. I take it you are enlarging 4*5 and that is another variable in the mix. For me the tricky part is knowing what you f-stop/speed is and what that looks like on the ground glass compared to the finished print. If your final print is not sharp enough, maybe you can go up one f-stop at a time until you get the printed image you want. It is just tricky to use these lenses. I understand the best of the old soft focus pictorial photos are contact prints. Good Luck, David

[David A. Goldfarb]

There is a very good post with some historical perspective on this topic in this thread:

http://hv.greenspun.com/bboard/q-and-a-fetch-msg.tcl?msg_id=003WxF

[Geoffrey_1456]

Thanks, guys!

My primary interest is landscape/cityscape, so I can not re-create an ideal 5:1 light ratio. With the iris wide open, no matter which disk I use, I just can't focus well. It must be an aging issue (I'm now really wishing for an AUTOFOCUS Large Format camera!). However, if I close down the iris to about F11, focusing is OK. Then, open the iris and shoot. The Polaroids looked fine. Does this procedure cause any focus shift in theory? Bob, could you please explain to me how focus shift work? Thanks,

[Bob Salomon]

Yes, call me at 800 735 4373 and I can answer all of your questions at one time.

[Paul Schilliger]

I am glad the question was asked and thank you, Bob for your reply. The bright s potlight placed in the field of focus is a good idea! I seize this opportunity to ask you if the stars (spoke wh eels) produced on film by small light sources such as candels is something one can avoid by changing disks or op enings, or is it part of the Imagon design, like the white rings are part of the mirror lenses design?

[Bob Salomon]

All disks produce stars

[Geoffrey_1456]

Thanks, Bob!

[cosmicexplosion]

Yes, call me at 800 735 4373 and I can answer all of your questions at one time.

but then we all would be in the dark!