W-A lens for 8x10

One other comment: You suggested Rodenstock APO Ronars. In the 240mm
focal length, the image circle is 212 (according to
http://graflex.org/lenses/lens-spec.html. Are they wrong? Richard
(above) mentioned that for 8x10, min. coverage is 302mm.

RON

"Ron Gans" wrote in message
oups.com...
One other comment: You suggested Rodenstock APO Ronars. In the 240mm
focal length, the image circle is 212 (according to
http://graflex.org/lenses/lens-spec.html. Are they wrong? Richard
(above) mentioned that for 8x10, min. coverage is 302mm.


No, I think that is right: when you said 'up close' I assumed you meant as
in macro work.

If you want to shoot a truck, you will need a lens that covers at near to
infinity focus, since you'll be a good twenty times the focal length or more
away. Maybe a Schneider Super-Angulon 165mm f8 is going to be the sort of
thing you need?



Peter

"Ron Gans" wrote in message
oups.com...
One other comment: You suggested Rodenstock APO Ronars. In
the 240mm
focal length, the image circle is 212 (according to
http://graflex.org/lenses/lens-spec.html. Are they wrong?
Richard
(above) mentioned that for 8x10, min. coverage is 302mm.

RON


The older Apo-Ronar lenses are four element process
lenses of the same general type as the Goerz Apochromatic
Artar. They have very narrow converage, oficially around 45
to 48 degrees at infinity, but for pictorial use they will
generally cover a film with a diagonal equal to the focal
length. Since the corrections are quite stable with object
distance they will perform well at infinity focus if stopped
down a little. This type of lens is typically very slow. The
Apo Ronar-S is a six element lens but also has narrow
coverage.
Rodenstock's standard lens for LF is the Sironar. The
original Sironar is a Plasmat, six elements in four groups,
with coverage on the order of 75 degrees at infinity focus.
It is very similar to the f/5.6 version of the Schneider
Symmar (there was an older version of the Symmar at f/6.8
but this is a Dagor knock-off). Rodenstock's wide angle lens
is the Grandagon. Even older ones are excellent lenses.
Process lenses are intended for making half-tone printing
plates. The older ones were usually four element "dialyte"
types. Some are apochromatically corrected for three-color
work. These have quite narrow coverage angles but excellent
performance. They are usually optimized for image to object
size ratios of 1:1 to 1:5. A second type of process lens
became popular in the 1960s. This is the so called wide
angle process type. These were designed to make plates for
printing by off-set lithography. In this process the entire
page is pasted up and photographed where the older type of
lens was used to make "cuts" to be inserted in letter press
work. Most of these WA lenses are not apochromatic but are
nonetheless highly color corrected. They are typically of
the Plasmat type, have coverage of around 60 to 70 degrees
at infinity focus, and are optimized for 1:1 or close to it.
The are closer to copy machine lenses than to the older
process lenses. These have been available at very low prices
on the used market although the supply has dried up
somewhat. They work fine for pictorial use.
Even older versions of the Sironar and Symmar are very
good lenses, about the best available at the time they were
made. While each company claims to have made the best I
think there is little difference in practice. Old Schneider
Symmars are convertible, that is, the back element is
corrected for use alone with the front element removed.
Schneider thought this would be a useful feature but most
users prefered a lens which was optimized for best
performance as a unit so later versions are not made
convertible. Nonetheless both the front and rear of any
Plasmat can be used alone as a long focus lens with pretty
good performance if stopped down. Ideally, the lens should
be behind the diaphragm, but since neither the lens or the
distance from the diaphragm is optimized for this use there
is not much difference in practice. The advantage of using
the single cell on the front is that the bellows draw is
significantly less. This is partly due to the location of
the lens but mostly because the principle points of this
type make them some what telephoto when used in front of the
stop and somewhat retrofocus when used behind it.

There are many older lenses of very good performance.
While the newest and latest may be better the difference is
sometimes marginal.
There is a good index of LF lenses at:
http://largeformatphotography.info//lenseslist.html


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Richard Knoppow
Los Angeles, CA, USA

Someone can correct me if this is a wrong assessment, but
if you're doing close-up work and bellows draw increases in
relationship
to the focal length for a given magnification,
maybe something really wide line the Wollensak 6 1//4" (159mm)
will allow for a good magnification and more modest bellows draw.

Collin
KC8TKA

"Cheesehead" wrote in message
oups.com...
Someone can correct me if this is a wrong assessment, but
if you're doing close-up work and bellows draw increases
in
relationship
to the focal length for a given magnification,
maybe something really wide line the Wollensak 6 1//4"
(159mm)
will allow for a good magnification and more modest
bellows draw.

Collin
KC8TKA

The coverage of a lens increases when its used for close
work. At 1:1 the image circle is double what it is at
infinity. If you are doing micro work, i.e., image larger
than the object, turn the lens around.
For "macro" work, that is close work where the image is
still smaller than the object, enlarger lenses work very
well. They are optimized for about the right distance. They
also make good micro lenes when turned around.


--
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Richard Knoppow
Los Angeles, CA, USA