A bad lens ....?

On Mon, 08 Dec 2003 08:08:26 -0800, Art Reitsch <ar7500 DeleteThis @olympus.net>
wrote:

 >I just bought a Schneider Super-Angulon 65mm f5.6 lens on eBay that
 >doesn't seem to work right. Or is it me? If a bought a dog, fine, I'll
 >deal with it. I seem to have a lot of trouble getting everything on the
 >ground glass to be in focus. It doesn't act like my other lens: 90,
 >and 210mm.

-snip-

  Dumb question here - what kind of bellows are you using? A
65mm will focus very close to the gorund glass, and if you are not
using a batg bellows, but a regular "folded" or pleated bellows, the
pressure from the bellows being comrpessed to much will be enough to
push your lens out of focus.

  Remember, ti does not take very much to push it unevenly out
of focus. I had this exact same happen to me several years ago,a nd
goign to a bag bellows and later a recessed lens board solved that
problem.
joe



<a style='text-decoration: underline;' href="http://www.oneilphoto.on.ca" target="_blank">http://www.oneilphoto.on.ca</a><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: A bad lens ....? 

 >I just bought a Schneider Super-Angulon 65mm f5.6 lens on eBay that
 >doesn't seem to work right. Or is it me? If a bought a dog, fine, I'll
 >deal with it. I seem to have a lot of trouble getting everything on the
 >ground glass to be in focus. It doesn't act like my other lens: 90,
 >and 210mm. I thought that on a scenic I could focus into the scene
 >somewhere and everything would be sharp. I adjust front and back
 >movements for a long time and maybe get everything into focus, but maybe
 >not. Is this normal for a wide angle lens, or is there something wrong
 >with it?
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If you have no trouble getting everything sharp with your 90mm you should not
have any trouble with a good 65mm S Angulon.

First, after zeroing the camera, check the groundglass image with your 90mm
again (focus on a medium distance flat object, a wall with plenty of detail
will do) - if everything looks right don't touch anything and mount the 65mm on
the camera.

If after careful re-focusing you don't have a sharp image to the corners the
fault is definitely with the lens.

Carefully remove both front and rear cells from the shutter assembly and see if
the mounting threads are smooth and easy.

Then check the cells themselves: shake them gently to listen for rattles that
would indicate loose elements.

Also, look at the way the shutter is mounted. Many shutters come with an
"anchoring" stud in the rear whose sole purpose is to prevent the lens from
shifting on the lens board. It requires drilling a small hole in the lensboard
for the stud to fit into, but many people are not aware of this problem and
mount the lens without removing the stud or drilling the necessary hole. The
result is that the shutter will not fit flat against the board and the focusing
will be uneven (there might even be light leaks!).

Good luck and keep us posted.



Bob G<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: A bad lens ....? 

Quoth Art Reitsch <ar7500 RemoveThis @olympus.net>:
| I just bought a Schneider Super-Angulon 65mm f5.6 lens on eBay that
| doesn't seem to work right. Or is it me? If a bought a dog, fine, I'll
| deal with it. I seem to have a lot of trouble getting everything on the
| ground glass to be in focus. It doesn't act like my other lens: 90,
| and 210mm. I thought that on a scenic I could focus into the scene
| somewhere and everything would be sharp. I adjust front and back
| movements for a long time and maybe get everything into focus, but maybe
| not. Is this normal for a wide angle lens, or is there something wrong
| with it?

If you have a stack of old View Camera magazines, you might look
for a series of articles some years back by Lyn Jones. In one of
them, he says that wide angle lenses have a noticeably curved focus
field, with the edges nearer than the center.

If I had ever used a wide angle lens myself I probably would have
known better than to bring this up, but it does sound plausible -
I mean, the existence of special "flat field" optics does seem to
imply that the field of others is not so flat. At any rate, it's
something to look for. If you find that it matches what you see,
then I guess you could expect the same from any other lens of that
design.

  Donn<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: A bad lens ....? 

Donn Cave wrote:
 > Quoth Art Reitsch <ar7500.DeleteThis@olympus.net>:
 > | I just bought a Schneider Super-Angulon 65mm f5.6 lens on eBay that
 > | doesn't seem to work right. Or is it me? If a bought a dog, fine, I'll
 > | deal with it. I seem to have a lot of trouble getting everything on the
 > | ground glass to be in focus. It doesn't act like my other lens: 90,
 > | and 210mm. I thought that on a scenic I could focus into the scene
 > | somewhere and everything would be sharp. I adjust front and back
 > | movements for a long time and maybe get everything into focus, but maybe
 > | not. Is this normal for a wide angle lens, or is there something wrong
 > | with it?
 >
 > If you have a stack of old View Camera magazines, you might look
 > for a series of articles some years back by Lyn Jones. In one of
 > them, he says that wide angle lenses have a noticeably curved focus
 > field, with the edges nearer than the center.
 >
 > If I had ever used a wide angle lens myself I probably would have
 > known better than to bring this up, but it does sound plausible -
 > I mean, the existence of special "flat field" optics does seem to
 > imply that the field of others is not so flat. At any rate, it's
 > something to look for. If you find that it matches what you see,
 > then I guess you could expect the same from any other lens of that
 > design.

All lenses have some field curvature. That means that the points in
exact focus won't form a plane at fixed distance from the lens. Instead
they will form a curved surface usually pretty close to being a plane.
For a wide angle lens, it is harder to reduce the curvature of that
surface. On the other hand, because of increased depth of field, it
shouldn't matter quite as much. It seems to me that even a 65 mm lens
made by Schneider should not be so bad that the field curvature would
cause the problems described.

 >
  > Donn<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: A bad lens ....? 

Problem solved, thanks to a reply above that got me thinking. The front
and back sections of the lens were not tightly screwed together. This
was caused by the thickness of my lens board, a Wisner. So now they are
tight, and I have some shims in place to keep the lens package tight
against the lens board with the locking nut removed. Longer story than
that, but the point is to be sure the front and back lens sections are
tight together. Just shot a great test neg.
Art

Leonard Evens wrote:

 > Donn Cave wrote:
 >
  >> Quoth Art Reitsch <ar7500.DeleteThis@olympus.net>:
  >> | I just bought a Schneider Super-Angulon 65mm f5.6 lens on eBay that
  >> | doesn't seem to work right. Or is it me? If a bought a dog, fine,
  >> I'll | deal with it. I seem to have a lot of trouble getting
  >> everything on the | ground glass to be in focus. It doesn't act like
  >> my other lens: 90, | and 210mm. I thought that on a scenic I could
  >> focus into the scene | somewhere and everything would be sharp. I
  >> adjust front and back | movements for a long time and maybe get
  >> everything into focus, but maybe | not. Is this normal for a wide
  >> angle lens, or is there something wrong | with it?
  >>
  >> If you have a stack of old View Camera magazines, you might look
  >> for a series of articles some years back by Lyn Jones. In one of
  >> them, he says that wide angle lenses have a noticeably curved focus
  >> field, with the edges nearer than the center.
  >>
  >> If I had ever used a wide angle lens myself I probably would have
  >> known better than to bring this up, but it does sound plausible -
  >> I mean, the existence of special "flat field" optics does seem to
  >> imply that the field of others is not so flat. At any rate, it's
  >> something to look for. If you find that it matches what you see,
  >> then I guess you could expect the same from any other lens of that
  >> design.
 >
 >
 > All lenses have some field curvature. That means that the points in
 > exact focus won't form a plane at fixed distance from the lens.
 > Instead they will form a curved surface usually pretty close to being
 > a plane. For a wide angle lens, it is harder to reduce the curvature
 > of that surface. On the other hand, because of increased depth of
 > field, it shouldn't matter quite as much. It seems to me that even a
 > 65 mm lens made by Schneider should not be so bad that the field
 > curvature would cause the problems described.
 >
  >>
  >> Donn
 >
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: A bad lens ....? 

If you lens turns out to be truly bad, and I mean REAL bad, then you might
be able to sell it to Sally Mann.
 >> Stay informed about: A bad lens ....? 

 >
 > If you lens turns out to be truly bad, and I mean REAL bad, then you might
 > be able to sell it to Sally Mann.

who, it seems, manages to take far better pictures with old "bad" lenses
than most of us can with the latest apo xl/hm super schneidagon...<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: A bad lens ....? 

In article <J5zBb.137$Af1.9126@news20.bellglobal.com>, "sympatico.ca"
<sympatico.TakeThisOut@sympatico.ca> wrote:

  > >
  > > If you lens turns out to be truly bad, and I mean REAL bad, then you might
  > > be able to sell it to Sally Mann.
 >
 > who, it seems, manages to take far better pictures with old "bad" lenses
 > than most of us can with the latest apo xl/hm super schneidagon...

Indeed. A good photograph is not always technically correct. I love it
when the grain sniffing resolution target mavens go ballistic over her
work.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: A bad lens ....? 

On Wed, 10 Dec 2003 08:19:26 -0600, nospam DeleteThis @nospam.xxx (jjs) wrote:

 >Indeed. A good photograph is not always technically correct. I love it
 >when the grain sniffing resolution target mavens go ballistic over her
 >work.

  Heh heh ! You actually pay attention to them ? But I will
agree with some that state that an image should not be over-enlarged.
For example I shot the image I have on my website using P3200 pushed a
lot. After all it's an EI800 film. I don't think this would hold up
well as an 8X10 much less as a larger image. The grain is quite
apparent in a 5X7.


Regards,

John S. Douglas, Photographer - <a style='text-decoration: underline;' href="http://www.darkroompro.com" target="_blank">http://www.darkroompro.com</a>
Please remove the "_" when replying via email<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: A bad lens ....?