Strange Lens: APO-Rodagon D 75 f/4 with NO Iris

Can someone help me with this little mystery... I have in my hands an
APO-Rodagon D 74 f/4 lens. Marked on the barrel is "1:1".

I know this lens is optimized for 1:1 reproduction and I would like to
use it for macro photography.

A version of this lens is current at Rodenstock and B&H. Related
designs are 75mm f/4.5 optimized for 2:1, and a longer focal length.

The lens I have has no diaphram (that is, no iris). A marginal photo
of the lens is at

http://www.karash.com/private/rodagonNoIris.jpg

1. What is the intended application of this lens?

2. What's the optimal use of this lens? Since it has no diaphram, I
assume it's intended to be used wide open?

3. What is the optimum aperture for use of this lens at 1:1? Is it
f/4 nominal which is actually f/8 at 1:1? Or would the optimum
aperture be stopped down? (I'm thinking of flat subjects, not 3-D
objects.)

4. Finally, the lens I have comes apart easily into two parts. Would
one place a fixed iris between the two parts?

Anyone else ever seen this lens?

-=- Rick

p.s. Here's Rodenstock's verbage about optimum aperture, which I find
confusing: "The optimum working aperture is between f/5.6 and f/8.
This is worth mentioning because the effective aperture of a lens
focused for a scale of about 1:1 is approximately two f-stops smaller
than the nominal aperture and therefore stopping down to smaller
apertures than nominal f/8 would result in visible blur because of
diffraction. All three models are fitted with click-stop aperture rings
which can be disabled and with pre-setting rings."

--
Richard Karash
Richard "at" Karash "dot" com

In article ,
Richard Karash wrote:

Can someone help me with this little mystery... I have in my hands an
APO-Rodagon D 74 f/4 lens. Marked on the barrel is "1:1".

I know this lens is optimized for 1:1 reproduction and I would like to
use it for macro photography.

A version of this lens is current at Rodenstock and B&H. Related
designs are 75mm f/4.5 optimized for 2:1, and a longer focal length.

The lens I have has no diaphram (that is, no iris). A marginal photo
of the lens is at

http://www.karash.com/private/rodagonNoIris.jpg

1. What is the intended application of this lens?

It is an OEM version built for a specific scanner.

2. What's the optimal use of this lens? Since it has no diaphram, I
assume it's intended to be used wide open?

1:1 dupes wide open.

3. What is the optimum aperture for use of this lens at 1:1? Is it
f/4 nominal which is actually f/8 at 1:1? Or would the optimum
aperture be stopped down? (I'm thinking of flat subjects, not 3-D
objects.)

5.6 to 8.0 if you aare looking at the standard 75mm 4.0 Apo Rodagon D

4. Finally, the lens I have comes apart easily into two parts. Would
one place a fixed iris between the two parts?

No

Anyone else ever seen this lens?

The standard one yes. There are 3 of them sold for photo use. The 75mm
4.0 the 75mm 4.5 and the 120. They are all with aperture unless they are
intended for a specific OEM application that does not require a variable
aperture.

-=- Rick

p.s. Here's Rodenstock's verbage about optimum aperture, which I find
confusing: "The optimum working aperture is between f/5.6 and f/8.
This is worth mentioning because the effective aperture of a lens
focused for a scale of about 1:1 is approximately two f-stops smaller
than the nominal aperture and therefore stopping down to smaller
apertures than nominal f/8 would result in visible blur because of
diffraction. All three models are fitted with click-stop aperture rings
which can be disabled and with pre-setting rings."

--
To reply no_ HPMarketing Corp.

In article ,
Bob Salomon wrote:

In article ,
Richard Karash wrote:

Can someone help me with this little mystery... I have in my hands an
APO-Rodagon D 75 f/4 lens. Marked on the barrel is "1:1".

I know this lens is optimized for 1:1 reproduction and I would like to
use it for macro photography.

....snips here and below...

The lens I have has no diaphram (that is, no iris). A marginal photo
of the lens is at

http://www.karash.com/private/rodagonNoIris.jpg

1. What is the intended application of this lens?

It is an OEM version built for a specific scanner.

2. What's the optimal use of this lens? Since it has no diaphram, I
assume it's intended to be used wide open?

1:1 dupes wide open.

3. What is the optimum aperture for use of this lens at 1:1? Is it
f/4 nominal which is actually f/8 at 1:1? Or would the optimum
aperture be stopped down? (I'm thinking of flat subjects, not 3-D
objects.)

5.6 to 8.0 if you aare looking at the standard 75mm 4.0 Apo Rodagon D

Thanks, Bob. I appreciate your contributions to this usenet group!

I'm still trying to understand this lens and what I might be able to
use it for. Since this lens is optimized for 1:1, the rest of this
post will all be about photographing at 1:1.

I have been doing some reading and experiments in macro photography.
(Dan Fromm's postings here, a couple of books he recommended, and
http://www.clarkvision.com/imagedetail ) I understand that if you are
going to hold fine detail (say 100 lp/mm at 50% MTF which is roughly
200 lp/mm at 10% MTF) then you'll keep diffraction out of the way at
effective aperture of f/8 (chart on the clarkvision.com page). That's
the aperture you'll want to use for flat subjects; it gives the most
depth of field without loss due to distortion. DOF gives you wiggle
room on focusing and it gives sharpness if the subject is not perfectly
flat.

This lens is nominally f/4, so at 1:1 the effective aperture is f/8.
Therefore, it's a good lens if you are going to work at this
resolution. This image detail is possible on fine slow films, but not
on a typical DSLR.

If you are only holding fine detail at half that resolution on the film
or sensor, then you'll want double the effective f ratio, that is,
f/16. I'm thinking this lens, with no iris, is wider than optimal for
1:1 on the D70. In a quick test, it does deliver the max image detail
I've seen on the D70 (40 lp/mm 50% MTF), but other lenses will do the
same at f/5.6 or f/8, so using the Rodagon D is wasting the opportunity
to get a smidge more depth of field.

This APO-Rodagon D is optimal for very high resolution photography of
flat subjects on fine slow films.

Does this sound right?

-=- Rick

In article ,
Sally Shears wrote:

This APO-Rodagon D is optimal for very high resolution photography of
flat subjects on fine slow films.

Not necessarily. It might have been one made to scan addresses
automatically at the post office in an automatic sorter. Or it might
have been used for duping negatives or slides in a high speed
duplicator. Or it could have been part of a scanner used in QC on a
production line.


All duplicating films were always slow. Even those used with the normal
Apo Rodagon D with an aperture.

To find out what your lens was made from you would ask whoever sold it
what machine it was taken out of.

--
To reply no_ HPMarketing Corp.

Richard Karash wrote:
Can someone help me with this little mystery... I have in my hands an
APO-Rodagon D 74 f/4 lens. Marked on the barrel is "1:1".

I know this lens is optimized for 1:1 reproduction and I would like to
use it for macro photography.

A version of this lens is current at Rodenstock and B&H. Related
designs are 75mm f/4.5 optimized for 2:1, and a longer focal length.

The lens I have has no diaphram (that is, no iris). A marginal photo
of the lens is at

http://www.karash.com/private/rodagonNoIris.jpg

1. What is the intended application of this lens?


duplicating films or making internegatives?

David.

In article . com,
" wrote:

Richard Karash wrote:
Can someone help me with this little mystery... I have in my hands an
APO-Rodagon D 74 f/4 lens. Marked on the barrel is "1:1".

I know this lens is optimized for 1:1 reproduction and I would like to
use it for macro photography.

A version of this lens is current at Rodenstock and B&H. Related
designs are 75mm f/4.5 optimized for 2:1, and a longer focal length.

The lens I have has no diaphram (that is, no iris). A marginal photo
of the lens is at

http://www.karash.com/private/rodagonNoIris.jpg

1. What is the intended application of this lens?


duplicating films or making internegatives?

David.

It came out of a scanner or duplicator that someone salvaged. Without
knowing what it came out of your question can't be answered. It could
have been a lens that scanned products on a belt for QC work. It could
have been a lens used to scan addresses at the Post Office, it could
have come out of a film scanner or an automatic film duplicator.

Unfortunately for you none of the above are optimized for the same thing
so while one version may be fantastic for duping at 1:1 another may be
poor at the same.

--
To reply no_ HPMarketing Corp.

Richard Karash wrote:
Can someone help me with this little mystery... I have in my hands an
APO-Rodagon D 74 f/4 lens. Marked on the barrel is "1:1".

I know this lens is optimized for 1:1 reproduction and I would like to
use it for macro photography.

Go right ahead.

As for use, darned if I know. Projecting a 2" field onto another
2" field is a bit odd.

Duplicating 70mm film? Though I think movies are duped by contact
printing.

75mm and 1:10 or 7.5mm at 1:1 would be more typical for machine
vision applications.

Fabricating power electronic components: 'hockey puck'
thyristors and diodes use 1-2" wafers? Wafer stepper -
but 1:1???

Maybe Bob Solomon will grace us with a solution to the
mystery.

Although optimized for 1:1 I am sure it will work perfectly
well over a 1:10:1 range.

--
Nicholas O. Lindan, Cleveland, Ohio
Darkroom Automation: F-Stop Timers, Enlarging Meters
http://www.nolindan.com/da/index.htm
n o lindan at ix dot netcom dot com