8X10 B&L ZEISS PROTAR SERIES IV info needed

Hi Guys,
Recently I bought this lens, the seller's description was vague and
picture was too small... and I was hoping it was a 8x10 Series V
protar, since I know a 183mm Series V would cover 7x17. But after the
lens arrived I found out it is a Series IV 8x10.

I could not find much information about the Series IV on the web,
except that it covers 100 degrees at smaller apertures (f45?), and the
focal length of a 8x10 Series IV is about 195mm.

Will this lens cover 7x17? I don't have a 7x17 camera yet to test it
myself right now...

In general, how Series IV Protars compare to Series V Protars, in terms
of contrast, sharpness at the edges and etc?

Thanks a lot!
Wenbiao

wrote in message
ps.com...
Hi Guys,
Recently I bought this lens, the seller's description was
vague and
picture was too small... and I was hoping it was a 8x10
Series V
protar, since I know a 183mm Series V would cover 7x17.
But after the
lens arrived I found out it is a Series IV 8x10.

I could not find much information about the Series IV on
the web,
except that it covers 100 degrees at smaller apertures
(f45?), and the
focal length of a 8x10 Series IV is about 195mm.

Will this lens cover 7x17? I don't have a 7x17 camera yet
to test it
myself right now...

In general, how Series IV Protars compare to Series V
Protars, in terms
of contrast, sharpness at the edges and etc?

Thanks a lot!
Wenbiao

Is this a Zeiss or a Bausch & Lomb Protar? Zeiss
discontinued the Series IV very early and I can't find info
on it in my 1920's Zeiss catalogues. Bausch & Lomb, who
built Zeiss design lenses under contract, continued to make
the Series IV until the 1940's. The Series IV is a
medium-wide-angle lens. My c.1912 B&L catalogue gives the
focal length of the 8x10 version as 7-11/16th inches. B&L
claims a coverage of greater than 100 degrees for this lens
but 90 degrees is probably closer to the mark. A 90 degree
lens will cover an image circle of about twice its focal
length at infinity focus so this one should work even if its
coverage is a bit less.


--
---
Richard Knoppow
Los Angeles, CA, USA

Richard, Thanks for the reply.

The text on the lens are "8x10 Bausch & Lomb-Zeiss Protar Series IV
PAT. JAN 13 1891 No.9151xx"

I assume 1891 is not the date the lens was produced? I read the past
posts (some of yours), that B&L did not begin to produce Protar lenses
until 1900s, and after 1910 the patent law required the exact patent
number printed on the lens instead just patent dates. So I guess this
lens was made between 1900 and 1910?

On http://www.cameraeccentric.com, the B&L 1910s' catelog (same as
yours?)
The same lens covers 8x10 at f12.5 and 10X12 at smaller stops.
http://www.cameraeccentric.com/img/i...chcatb/p29.jpg

On the B&L 1920 catelog, the same protar IV lens with 7 11/16 focal
length, covers 6.5X8.5 at f12.5, and 8x10 at smaller stops.
http://www.cameraeccentric.com/img/i.../coveragef.jpg

So, I guess B&L became more conservative about their lenses' coverage
later on?

Any idea on the performance and characteristic diffrences between the V
and IV protars?

Thanks,
Wenbiao

Richard Knoppow wrote:
Is this a Zeiss or a Bausch & Lomb Protar? Zeiss
discontinued the Series IV very early and I can't find info
on it in my 1920's Zeiss catalogues. Bausch & Lomb, who
built Zeiss design lenses under contract, continued to make
the Series IV until the 1940's. The Series IV is a
medium-wide-angle lens. My c.1912 B&L catalogue gives the
focal length of the 8x10 version as 7-11/16th inches. B&L
claims a coverage of greater than 100 degrees for this lens
but 90 degrees is probably closer to the mark. A 90 degree
lens will cover an image circle of about twice its focal
length at infinity focus so this one should work even if its
coverage is a bit less.


--
---
Richard Knoppow
Los Angeles, CA, USA

wrote in message
ups.com...
Richard, Thanks for the reply.

The text on the lens are "8x10 Bausch & Lomb-Zeiss Protar
Series IV
PAT. JAN 13 1891 No.9151xx"

I assume 1891 is not the date the lens was produced? I
read the past
posts (some of yours), that B&L did not begin to produce
Protar lenses
until 1900s, and after 1910 the patent law required the
exact patent
number printed on the lens instead just patent dates. So I
guess this
lens was made between 1900 and 1910?

On http://www.cameraeccentric.com, the B&L 1910s' catelog
(same as
yours?)
The same lens covers 8x10 at f12.5 and 10X12 at smaller
stops.
http://www.cameraeccentric.com/img/i...chcatb/p29.jpg

On the B&L 1920 catelog, the same protar IV lens with 7
11/16 focal
length, covers 6.5X8.5 at f12.5, and 8x10 at smaller
stops.
http://www.cameraeccentric.com/img/i.../coveragef.jpg

So, I guess B&L became more conservative about their
lenses' coverage
later on?

Any idea on the performance and characteristic diffrences
between the V
and IV protars?

Thanks,
Wenbiao

My catalogue is a bit different from the 1910 one on the
Camera Eccentric site. I am guessing at the date based on a
list of cameras using B&L lenses included in the catalogue,
I think it may be older.
B&L was considerably more liberal than Zeiss in their
coverage claims often giving the "small stop" coverage only
where the Zeiss catalogue lists coverage with lenses wide
open. "Small stops" usually means f/45.
I miswrote about the expected coverage of this lens, it
will _not_ cover 7x17. The image circle at infinity will be
about 16 inches, I am not sure what I was thinking about but
had not had my morning coffee yet.
The basic design of the IV and V are the same. Both are
essentially Paul Rudolph's original Protar design but made
to have larger coverage by making them slower. The Series V
Extra Wide Angle lens, which will cover at least 105
degrees, is only f/18 wide open and must be used at f/45 for
maximum coverage.
In general, this type of lens has good performance but
Rudolph abandoned it for other designs, notably the Tessar
and Planar, which were capable of better performance-- but
NOT as wide angle lenses, where the Series V continued to be
made until the 1940's, maybe later.
The famous Convertible Protar has four elements in each
half, essentially each is a cemented version of the earlier
lens with all four elements cemented. However, the
performance of a single Convertible Protar cell is not as
good as the older type.
The US government ruled that products made from 1927 must
carry the actual patent number rather than just a patent
date; there were just too many patents being issued.
However, may products made earlier had patent numbers on
them so this is not by itself a sure way of dating. The name
Bausch & Lomb - Zeiss is somewhat better: the agreement
between Zeiss and B&L ended with the outbreak of WW-1 in
1914 so lenses marked with this trade name were made no
later than 1914 or 1915. B&L continued to make Zeiss design
lenses with Zeiss names until the 1950's, particularly the
Tessar, Protar, MicroTessar, and a couple of others.
I have never found a key to B&L serial numbers other than
a partial key to late ones. It appears that each type of
lens had a separate serial number sequence. For instance I
have a list of numbers for the Micro Tessar which could not
possibly fit B&L's regular Tessars. I have been looking for
B&L serial number info for a long time and not found
anything. I suspect that B&L's old business records no
longer exist so, unless someone has lists the info is
probably lost.
Before about 1941 B&L used all numerical serial numbers,
after 1941 they began to use a two letter prefix. Unlike the
Kodak serial number prefix, which is a date code based on
the key word CAMEROSITY the B&L code indicates the class of
lens and year of manufacture. The letters are not in order
so one must have the key. I also don't know for certain what
the colored dots found on some late B&L lenses mean.
In any case, your lens was made before 1915. The date is
the date of the patent. In the US patents, until very
recently, had a life of 17 years and can not be renewed.
Because some foreign patents are granted for a period of 20
years the US patent law recently was revised to allow
recognition of this. There is nothing to prevent the
indication of a patent on something after the patent has
expired.
The Protar was the first lens to employ the "new" Jena
glass types to form an anastigmatic. Originally Zeiss called
the lens the Anastigmat but the name proved impossible to
protect so it was changed to Protar. At the time the lens
was designed it was thought that it was impossible to make a
lens which was simultaneously free of astigmatism and color
corrected with the conventional glass types available before
Barium and other new glass types. In fact, this was not true
but such a lens was not designed until _after_ the new glass
types became available. Martins, of Busch (I think) designed
a four element air spaced lens that was both anastigmatic
and color corrected using only old type glasses.
I am sure this is more than you want to know. :-)


--
---
Richard Knoppow
Los Angeles, CA, USA

Richard,
Thanks for the detailed message, this is exactly what I was looking
for.

Whenever I buy a lens or a body, I would like to know the detailed
history about it, usually searching for old posts (some are yours and
some are from other people) will give me what I want to know, but your
replies to my question are what I am looking for this time. And it is
good to know (first time too) that anastigmat lens can be made from old
glass type.

One more question: since the patent date on my lens is 1891, and from
what you said: that a patent has 17 year life span, and doing the math,
it seems that 1908 will be last year B&L needs to/can print this
particula patent on a Protar lens? I mean, after 1908, B&L does not
have to "obey" this patent anymore? (I read it somewhere on the net
that the original protar lens patent was made in 1890 or 1891?)

In other words, this particular lens was made before 1908?

Thanks again for your detailed and very informational reply.

Wenbiao

wrote in message
ups.com...
Richard,
Thanks for the detailed message, this is exactly what I
was looking
for.

Whenever I buy a lens or a body, I would like to know the
detailed
history about it, usually searching for old posts (some
are yours and
some are from other people) will give me what I want to
know, but your
replies to my question are what I am looking for this
time. And it is
good to know (first time too) that anastigmat lens can be
made from old
glass type.

One more question: since the patent date on my lens is
1891, and from
what you said: that a patent has 17 year life span, and
doing the math,
it seems that 1908 will be last year B&L needs to/can
print this
particula patent on a Protar lens? I mean, after 1908, B&L
does not
have to "obey" this patent anymore? (I read it somewhere
on the net
that the original protar lens patent was made in 1890 or
1891?)

In other words, this particular lens was made before 1908?

Thanks again for your detailed and very informational
reply.

Wenbiao

I don't think there was anything in patent law to prevent
the printing of patent information on a product after the
patent has expired. Its quite possible the lens is that old
(1908 or before) but in the absence of serial number data I
don't know of any way to prove it.
A good source of general information about old lenses is
_A History of the Photographic Lens_
Rudolph Kingslake, 1989, San Diego, the Academic Press ISBN
0-12-408640-3 This is out of print but is sometimes
available used and good libraries should have it on
interlibrary loan.


--
---
Richard Knoppow
Los Angeles, CA, USA