Re: Home made Lenses ( soft focus )

----- Original Message -----
From: "Tom Ferguson" <tomf2468@pipeline.com>
To: <alt-photo-process-l@sask.usask.ca>
Sent: Friday, March 04, 2005 1:08 PM
Subject: Re: Home made Lenses ( soft focus )

> There are two things going on with my "Quartsite
> fleamarket lens".
>
> 1) I almost always use it wide open (about F/4.5) because
> the lens itself has no adjustable aperture. I made a set
> of waterhouse type stops to put in front of the lens, but
> like the wide open effect better for this project.
>
> 2) As Richard pointed out, the extreme loss of
> focus/resolution as you travel out of the center of the
> circle is probably coma error (actually I always say the
> word "croma", but suspect that Richard knows better than I
> do!). I love it (for this project). I use camera movements
> on the 4x5 to "put" the sweet in focus spot where I want
> in the composition. Great fun.
>
> My experience with soft focus lenses is that they are all
> different and interesting. There is no one "magic set of
> errors" that make a great soft focus lens. It isn't that
> simple. You try a few and see what works "for you and your
> project". I doubt many would find my "Quartsite fleamarket
> lens" a great choice for a soft focus portrait lens. "I"
> would much prefer my Wollensak for that use.
>
> On Friday, March 4, 2005, at 11:04 AM, John Cremati
> wrote:
>
>> Examples of Tom Ferguson photos:
>> http://www.ferguson-photo-design.com

   I wonder if this thing could be the back of a Tessar. In
the Tessar type lens the rear cell has most of the power,
the front most of the corrections. The front will have a
shorter focal length than the combined lens so the FL might
be a clue. Usually, the back is fairly well corrected for
color but has gobs of coma and spherical. An interesting
possiblity for a special effect since you can get it by
simply screwing off the front element of a Tessar type lens.
I say Tessar type because while Tessar is a trade name used
by Zeiss and Bausch & Lomb (originally by agreement with
Zeiss) it has also become a generic name for a type of
design. An great many Tessar type lenses have been made
under a great variety of names by nearly every maker of
photographic lenses that ever was.

---
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com