Rodensock APO-Sironar-S Focus Quality

Although I buy what you're saying here, if the focal plane changes when you
stop down, what good is the wide open setting for focusing? I'm not talking
about focus shift but if the flatness of field improves, how can you
determine what the focus point of the tilt being used etc is if the flatness
changes? I've not noticed this with my 135 WF ektar... Seems like if this is
true, wide open is useless for anything other than composition with this
lens.. I've also done some interesting shots wide open with my 8 1/2 inch
commercial ektar and while not the sharpest f-stop for this lens, I didn't
notice any field curvature with it..

 Stephe, being the devils advocate..

  The Apo-Sironar-S should be an exceptionally well corrected lens.
All lenses will improve in the corners when stopped down but the image
on axis for this lens should be very sharp even wide open. There
should be no detectable focus shift. Focus shift is caused by zonal
spherical aberration. That is the lens has a large amount of
uncorrected spherical from the part of the lens about half way between
the center and edge. This is inherant in cemented meniscus lenses like
the Dagor but should be nearly non-existent in modern Plasmat types.
  If your lens has focus shift and seems to have excessive field
curvature there is something wrong with it. These lenses should also
have nearly flat fields and very little astigmatism.
  It is possible that something is misassembled in the lens or that
there is some other manufacturing defect. Dogs should be caught at the
factory but they do escape sometimes.  The Apo-Sironar shold be one of
the finest lenses on the market, it should not have any of these
characteristics.
  It should be new enough to have some sort of warrenty on it. I would
contact Bob Salomon via phone or e-mail and ask for an evaluation of
it. Bob takes a lot of heat here but is very good at backing up the
products he sells. I am quite sure that if this lens was defective
from the factory Bob will arrange to have something done about it.

---
Richard Knoppow
Los Angeles, Ca.
dickb @ix.netcom.com

I have already answered with the offer to see fix any problem when he first
posted this question but am yet to receive any feed back from him.

While it is not impossible for a lens to be bad that doesn't mean it left
the factory that way.

1: this may not be a new lens.
2: It may have been mishandled in shipping.\

If it is bad, and it came from HP Marketing, we will solve the problem for
him.

But to do so he MUST contact us. The contact and warranty information are on
our warranty card.
--

HP Marketing Corp. U.S. distributor for Amazon, Braun, Gepe, Giottos,
Heliopan, HP Combi Plan T, Kaiser fototechnik, KoPho cases, Linhof, Pro
Release, Rimowa, Rodenstock, Sirostar 2000

----------
In article <37b3ae01.30594 @nntp.best.ix.netcom.com>,

Hello,

I posted the question concerning the quality of my lens on the large format
newsgroup. I would like to thank everyone who responded for the excellent
suggestions. Before I send in the lens, I feel I need to do more testing on my
end.

Per the suggestion of "skgrimes" I have already removed the lens to make sure
there was not a locater screw issue. I now want to set up my camera and look at
a brick wall and try to better characterize the focus shift to see if there are
any hints that my camera might be the problem.  I need to first clearly
determine if this is a camera issue or a lens issue. I still have my old 135mm
Optar to compare this lens with.

I did buy my lens "brand new" about two months ago. It was very well packaged
and I don't suspect any shipping damage. I'm looking forward to solving this
soon.

Thanks again.

Regards,

Mike Brown

<< I have already answered with the offer to see fix any problem when he first
posted this question but am yet to receive any feed back from him.

While it is not impossible for a lens to be bad that doesn't mean it left
the factory that way.

1: this may not be a new lens.
2: It may have been mishandled in shipping.\

If it is bad, and it came from HP Marketing, we will solve the problem for
him.

But to do so he MUST contact us. The contact and warranty information are on
our warranty card.
--

HP Marketing Corp. U.S. distributor for Amazon, Braun, Gepe, Giottos,
Heliopan, HP Combi Plan T, Kaiser fototechnik, KoPho cases, Linhof, Pro
Release, Rimowa, Rodenstock, Sirostar 2000
 >>

Try focusing on something like a brick wall.  Are all four corners
equally sharp?   Focus to optimize the center.   Does changing the focus
improve all four corners?   Just two at a time?   In the latter case,
the lens and film probably aren't parallel.

Most large-format lenses aren't designed to take photographs at maximum
aperture.   Maximum aperture is intended for composition and focusing.  
The rule of thumb is that good performance for taking begins about 2
stops down from maximum aperture.   Compared to a longer focal length
lens, this is probably more true with this 135 mm focal length lens.  
The 208 mm diameter image circle specified by Rodenstock is for f22.  
At f5.6 The corners might either have light falloff or be less sharp
than the center.   The MTF curve for f11 in Rodenstock's brochure shows
a falloff in quality beginning to be substantial at a radius of about 80
mm -- this is exactly at the corners of a 4x5 negative with no camera
movements.   The MTF curves they show for f22 are decidedly better.

In the application of night photography, this might not matter,
depending on the presence or absence of detail in the corners and the
degree of enlargement, etc.

This is not a criticism of Rodenstock lenses--this is the general
practice.  Rarely will a large format photographer want to take a
picture with a lens wide open, because of the limited depth of field.  
Making the lens better wide open would increase the complexity, weight
and cost of the lens.

The lens would be the last suspect on my list. You could check
that by rotating the lens 180 and see if the "tilt" follows.
After checking that the lens is flat on the lensboard
I would check the Super Graphic neutral stops to make sure they
are set correctly. Mine took a bit of work to get the infinity
and tilt stops set accurately. Something about the camera
was not entirely square as a caliper measure from front of the rail
was not accurate to set the infinity stops! Also, a tilt stop on
one side had to be adjusted. A bit of frustration but finally got
it straight and it works great! A 150 Sironar-S is my first lens
choice. Have you used this camera with another lens? Longer lenses
are a bit less sensitive to precise alignment. One nice thing about
the Super is the front tilt goes forward and back, unlike other
Graphics. Next time that problem happens, use the tilt!
Gary Frost

Check the simplest and most common things first:  Be sure the shutter is mounted on the lensboard in
such a way that the back element screws in all the way and touches the shutter, not the lensboard or
retaining ring.  Second, be sure the "locator screw" projecting from behind the shutter is missing.
Most new lenses are delivered with a plain hole on the back of the shutter that looks like a missing
screw.  Some lenses/shutters are delivered with this projecting screw (which is intended to fit into
a compatible hole bored in the lensboard) installed.  If no hole is provided in the lensboard and
the screw is not removed it can cause the entire lens to be tilted on the lensboard.  Both these
problems are very common. SKG

--

S.K. GRIMES  --  FEINMECHANIK  --  MACHINE WORK FOR PHOTOGRAPHERS

              +  Lenses mounted into shutters.
              +  Shutters repaired, restored.
              +  For more info--  http://www.skgrimes.com.
                            (updated 6-12-99)
                      mailto:skgri @skgrimes.com

In article <19990811172152.20737.00000 @ng-ch1.aol.com> , mjbr @aol.com



If you have checked Steve's suggestions. And then made sure the camera is in
alignment and you still have the same problem you should send it in to
service.

The service address is on your HP warranty card as the Rodenstock lenses
sold by HP Marketing have a Lifetime Warranty to the original purchaser. You
can call us at 800 735 4373 should you have questions.

--

HP Marketing Corp. U.S. distributor for Amazon, Braun, Gepe, Giottos, GO
Light, Heliopan, HP Combi Plan T, Kaiser fototechnik, KoPho cases, Linhof,
Pro Release, Rimowa, Rodenstock,Sirostar 2000

... and finally, after you have been through all the other adjustments
and checks, there is still the issue of field curvature.
You can see the effect with almost any lens on well set up 4x5 body.

If you find the edges to be slightly ahead of the centre... equally
and evenly on all sides, then you're probably looking at a well set up
camera.... and a lens with field curvature.
From there its a matter of studying the effects of stopping the lens
down and finding the best point at which to set your focus and
aperture.  Eventually you may find that using a point part-way out
from the centre is best.

All my lenses, from Apo Lanthar to Symmars exhibit field curvature.
When I first noticed it, whilst calibrating my first view camera, I
was very dissapointed.  Now I know that I was simply becoming aware of
a standard lens aberration and was being very picky.
Next you'll be finding a slew of other faults as well and it is a good
idea to check out a few brand new lenses on a perfect body just to get
an idea of what should be considered normal.

I would also argue that any lens used at its maximum aperture is not
going to perfom nearly as well as it can two stops down.  Therefore, a
nice 150mm f2.8 Xenotar might just give a flatter image at f5.6 than a
Sironar wide open at 5.6
I do have an old 2.8 Xenotar here, but I haven't made the
comparison.... might just do that later on today.