I'd like to challenge the view that 6x9 folders give soft pictures
RolandRB
I've heard this opinion oft repeated on websites that discuss medium
format. The view is that "the film is not flat" and so gives poor
results. I challenge that. I've just got the results back from a 1931
6x9 Zeiss Ikonta and there is no evidence of lack of film flatness
leading to poor focus. Because the camera is old, I tightened the
springs on the pressure plate before taking any photos and I always
wind on just before taking the shot, because it is only natural for
the film to warp over the plate in the heat over time, so I avoid
that. If I delay taking a photo after winding on - maybe waiting for
better light or sky - then I start to wind on to tighten the film and
then I get no problem.
People buying a Zeiss Ikon in those days with the Tessar (uncoated)
lens and the Compur rim shutter were paying something like the cost of
an automobile. They were not paying for crap and they did not get crap
either. They got a superb camera that was the best in the world and
way ahead of its time. My 1931 folder was designed for B+W film - it
has a red window at the back with no cover (I use insulating tape) -
but still this uncoated Tessar performs superbly throughout the colour
range. At 10x magnification using a lupe then I see slight camera
shake problems and, being a larger format, not everything in the scene
can be in sharp focus, but I consider this 1931 camera to be the near
equal of any other modern MF 6x9 camera.
Toni Nikkanen
I also just last week got my fourth folder of my life. The previous
three all had severe problems due to misuse by the former owners, but
this one, a Zeiss Super Ikonta 530/16, despite fungus inside the lens,
is performing really well. Pictures come out sharp and with no funny
effects like a swirling background etc. Previously I thought taking
pictures of backlit subjects with uncoated lenses would always result
in flare, but this uncoated 8cm/2.8 Tessar has proven me wrong.
Alan Browne
> I'd like to challenge the view that 6x9 folders give soft pictures.
> I've heard this opinion oft repeated on websites that discuss medium
> format. The view is that "the film is not flat" and so gives poor
> results. I challenge that. I've just got the results back from a 1931
> 6x9 Zeiss Ikonta and there is no evidence of lack of film flatness
> leading to poor focus. Because the camera is old, I tightened the
> springs on the pressure plate before taking any photos and I always
> wind on just before taking the shot, because it is only natural for
> the film to warp over the plate in the heat over time, so I avoid
> that. If I delay taking a photo after winding on - maybe waiting for
> better light or sky - then I start to wind on to tighten the film and
> then I get no problem.
If it were just the 'wind on' need, that would be of little concern.
From the various replies to my enquiry some time ago, I think there is
also the issue of RF focus errors to take into account. This is what
scared me off buying a used one a few months ago.
Richard Knoppow
"Alan Browne" <alan....@FreelunchVideotron.ca> wrote in
message
news:mqKdnQQtreORkMjX...@giganews.com...
The Super Ikonta has a very good rangefinder. Probably,
in a camera this old, it may need some adjustment, mostly to
make sure the infinity point is set properly.
It is an error to think that flare exists only for
back lighted scenes the flare in uncoated lenses is there
all the time. The amount depends on the number of air-glass
surfaces and goes up exponentially as the number of surfaces
increases. For a relatively simple lens like a Tessar the
flare is not bad. Backlighting can bring out other sources
of flare such as reflections from the lens mount and from
the insides of the camera. Those are also always present but
strong light within the image area can make them more of a
problem. In general a good uncoated Tessar has pretty good
contrast.
The Tessar in the Ikonta series is a front element
focusing lens. This is a very elementary zoom lens whose
focal length is changed to change focus. The problem is that
the corrections for aberrations change with the change in
focus and there is nothing in these simple lenses to
compensate for it. In general front element focusers are
designed to have the best correction at distant focus
because the assumption is that one will want the best
rendition of detail there.
Nonetheless, the Super-Ikonta series has an excellent
reputation for sharpness.
BTW, since the focal length of the lens is changed to
effect focus the viewing angle remains constant with
distance. For that reason a fixed finder such as used on the
Super-Ikonta is accurate at all distances (other than for
parallax).
--
Richard Knoppow
Los Angeles, CA, USA
dick...@ix.netcom.com
Richard Knoppow
"Richard Knoppow" <dick...@ix.netcom.com> wrote in message
news:X8SdnSVE_JH8jsjX...@earthlink.com...
attributed to film flatness are often actually due to focus
shift. I've found that even some very good lenses (Zeiss
Tessar, Kodak Ektar) have enough shift to affect the
accuracy of focus on a Speed Graphic using a rangefinder.
This would also apply to other types of cameras that do not
show focus directly at the f/stop used. Focus shift comes
from residual spherical aberration which is affected by the
stop. Usually, when stopped down perhaps two stops from
maximum, most of the spherical is gone. If a lens is focused
as best as possible when wide open and then stopped down a
couple of stops one finds that the point of best focus may
have changed. This effect is relatively large for lenses
like the Goerz Dagor, which as a large residual of
spherical, is less for Tessars, depending on the exact
design, and is minimal for the six element lenses of the
Biotar type and more complex lenses based on it commonly
used in 35mm cameras.
darkroommike
wall taken with an unknown 616 format camera circa 1942, I scanned the
negative for a family CD and then had a big digital print made just
for the heck of it and was blown away. I supect the camera was an old
zone focusing Kodak with one of the better Kodak lenses but the
negative and the print are darned sharp. I have no Idea what happened
to the camera but I wish I owed it.
On Jul 8, 4:51 pm, "Richard Knoppow" <dickb...@ix.netcom.com> wrote:
> "Richard Knoppow" <dickb...@ix.netcom.com> wrote in message
>
> news:X8SdnSVE_JH8jsjX...@earthlink.com...
>
>
>
> > "Alan Browne" <alan.bro...@FreelunchVideotron.ca> wrote in
>
> Another BTW, I rather think that focus problems
> attributed to film flatness are often actually due to focus
> shift. I've found that even some very good lenses (Zeiss
> Tessar, Kodak Ektar) have enough shift to affect the
> accuracy of focus on a Speed Graphic using a rangefinder.
> This would also apply to other types of cameras that do not
> show focus directly at the f/stop used. Focus shift comes
> from residual spherical aberration which is affected by the
> stop. Usually, when stopped down perhaps two stops from
> maximum, most of the spherical is gone. If a lens is focused
> as best as possible when wide open and then stopped down a
> couple of stops one finds that the point of best focus may
> have changed. This effect is relatively large for lenses
> like the Goerz Dagor, which as a large residual of
> spherical, is less for Tessars, depending on the exact
> design, and is minimal for the six element lenses of the
> Biotar type and more complex lenses based on it commonly
> used in 35mm cameras.
>
> --
> Richard Knoppow
> Los Angeles, CA, USA
RolandRB
The same camera worked less well at 1/200 shutter speed than 1/100.
There was very noticeable shake in nearly all the shots. I would have
thought it would be the other way round.
RolandRB
>
> - Show quoted text -
I got another roll back from my 1931 folder and all the photos are
sharp at 1/100th sec. The extra kick from the stronger spring for the
Compur shutter at 1/250th sec shakes every shot and ruins it. At least
I now know. It seems I am holding it steadier now at 1/100th sec. as
none of the photos had any detectable shake when carefully inspected
using a 10x lupe. I hyperventilate before taking the shot and shoot
between heart beats while pushing the camera harder against my face. I
have found in the past that this helps a lot.
The results from this old camera are so good that I would have no
hesitation in using it as my main camera when going on holiday for
doing bright light outdoor shots. It's coming with me to Munich
tomorrow. I was going to buy a monopod for it but I don't need one
now.
Richard Fateman
>
> The same camera worked less well at 1/200 shutter speed than 1/100.
> There was very noticeable shake in nearly all the shots. I would have
> thought it would be the other way round.
I'm not saying your explanation is wrong, but you might consider another
explanation that at 1/100 you were using a smaller f stop, thereby
increasing the "depth of focus", and thereby compensating for the film
not being flat!
It is possible to distinguish unflat-film softness from camera-moved
softness in some test images but maybe not all.
It seems to be well known that roll-film backs (e.g. for 6X9
Graflex),vary in ability to hold the film flat (lever vs. knob) but I
think you can experiment and look at the flatness by assembling a fake
roll of film with (exposed/processed) film taped in place, and just
looking at it to see if it visibly buckles. It probably will be visible.
You may be able to experiment to try out these ideas about whether to
advance the film just before exposure or not, to avoid some curl or fold
or whatever.
RolandRB
> RolandRB wrote:
> > On Jul 8, 8:38 am, RolandRB <rolandbe...@hotmail.com> wrote:
> ><snip>
>
> > The same camera worked less well at 1/200 shutter speed than 1/100.
> > There was very noticeable shake in nearly all the shots. I would have
> > thought it would be the other way round.
>
> I'm not saying your explanation is wrong, but you might consider another
> explanation that at 1/100 you were using a smaller f stop, thereby
> increasing the "depth of focus", and thereby compensating for the film
> not being flat!
When I wrote "very noticeable shake" then I mean clearly visible
double images due to shake. It's nothing to do with depth of focus.