Black and White film latitude ?

I would say a couple of stops either way. I have a 4x5 pinhole camera,
and have to take somewhat of a wild guess on exposure and then develop
by inspection <gasp> with a peek now and then with a dark green
safelight. I can get a quite printable negative 90% of the time. This
is with Plus x, tmax100, and the ASA 25 stuff - tech pan.

With my Retina IIa, I often don't bother with a light meter. Just use
the "sunny 16" rule and bracket the exposures.

It is disgusting how much latitude there is in B&W film.
 >> Stay informed about: Black and White film latitude ? 

On 1/11/2004 5:26 PM Paul W. Ross spake thus:

 > I would say a couple of stops either way. I have a 4x5 pinhole camera,
 > and have to take somewhat of a wild guess on exposure and then develop
 > by inspection <gasp> with a peek now and then with a dark green
 > safelight. I can get a quite printable negative 90% of the time. This
 > is with Plus x, tmax100, and the ASA 25 stuff - tech pan.

You should be able to get accurate exposures even with a pinhole camera. (I
also have a 4x5 pinhole camera, among other sizes.) You just need to know the
relative aperture, which you can easily compute from the size of the pinhole
and its "focal length" (distance from film):

rel. aperture = focal length / pinhole dia.

(Technically not absolutely correct, but close enough for jazz.)

Most pinhole cameras will be somewhere in the f/100-f/400 range.


--
Focus: A very overrated feature.

- From Marcy Merrill's lexicon at Junk Store Cameras
(http://merrillphoto.com/JunkStoreCameras.htm)<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Black and White film latitude ? 

David Nebenzahl wrote:
 >
 > On 1/11/2004 5:26 PM Paul W. Ross spake thus:
 >
  > > I would say a couple of stops either way. I have a 4x5 pinhole camera,
  > > and have to take somewhat of a wild guess on exposure and then develop
  > > by inspection <gasp> with a peek now and then with a dark green
  > > safelight. I can get a quite printable negative 90% of the time. This
  > > is with Plus x, tmax100, and the ASA 25 stuff - tech pan.
 >
 > You should be able to get accurate exposures even with a pinhole camera. (I
 > also have a 4x5 pinhole camera, among other sizes.) You just need to know the
 > relative aperture, which you can easily compute from the size of the pinhole
 > and its "focal length" (distance from film):
 >
 > rel. aperture = focal length / pinhole dia.
 >
 > (Technically not absolutely correct, but close enough for jazz.)
 >
 > Most pinhole cameras will be somewhere in the f/100-f/400 range.

Some years ago I produced a how-to on pinhole cameras. Here's a brief
chart on pinhole f stops and how to estimate exposure.

<a style='text-decoration: underline;' href="http://members.aol.com/nospam777/pinhole_exposure.html" target="_blank">http://members.aol.com/nospam777/pinhole_exposure.html</a><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Black and White film latitude ? 

In article <bts776$ql9$1@sparta.btinternet.com>,
"Robert Whitehouse" <bob.whitehouse DeleteThis @btinternet.com> wrote:

 > We all know that colour negative film has much greater latitude than
 > reversal (slide) film, but where does your typical black and white negative
 > film stand in this ?
 >
 > Is it closer to colour negative, or colour slide, from a latitude
 > perspective ?
 >
 > BW
 >
 >

Define the latitude you need. Are we talking under or over exposure?
Most BW fims handle overexposure well or shall we say well enough.

Underexposure not well at all.
In terms of the range of stops the film can represent given normal development
it depends on the developer, and the amount of exposure. Some have less than
five and some more than seven. Personally I like more than less.
--
LF website <a style='text-decoration: underline;' href="http://members.bellatlantic.net/~gblank" target="_blank">http://members.bellatlantic.net/~gblank</a><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Black and White film latitude ? 

"Robert Whitehouse" <bob.whitehouse.RemoveThis@btinternet.com> wrote in message news:<bts776$ql9$1@sparta.btinternet.com>...
 > We all know that colour negative film has much greater latitude than
 > reversal (slide) film, but where does your typical black and white negative
 > film stand in this ?
 >
 > Is it closer to colour negative, or colour slide, from a latitude
 > perspective ?
 >
 > BW

First, lets defind "latitude" so we are on the same track. Latitude
is the range of exposure possible without changing the tonal rendition
of the film.
The ISO method of measuring speed for B&W still negative film
yields about the minimum exposure which will give good shadow detail.
The reason for this is that thin negatives tend to be a little sharper
and a little finer grained than denser ones. This is mostly of
interest to 35mm users. As a result there is little latitude for
underexposures and a great deal for overexposures. Underexposure
latitude is no more than a stop without noticable loss of shadow
detail. OTOH, some films will take as much as ten stops overexposure
and still record a full range of scene brightness, though you may need
an arc light to print them.
Because the shape of the toe region of the characteristic curve
affects shadow contrast some films look better if given a bit more
exposure than the ISO method indicates. The ISO method does not take
into account the toe contrast as did the old Kodak method. However, it
is much easier to measure.
Most films will yield a bit better shadow detail if given a stop
more exposure than the ISO speed indicates.
Color films are processed using highly standardized methods, not
true of B&W negative film. The methods prescribed in the ISO standards
for color films is different from those for B&W negative. Color
negative film in theory has as much latidude as B&W negative (after
all that is what it basically is) but other problems occur with
tracking of the various emulsion layers, etc., so the practical
latitude is less. Nonetheless, modern color negative films will
tollerate considerable exposure error and still give acceptable
results.
Reversal processes, including color transparency materials, are much
more critical of exposure. This is partly because the exposure must
leave enough silver halide to produce the final positive image (even
when it is only an intermediate as in color film). The other, and
probably more important reason is that reversal films are generally
much higher in contrast than negative materials so that they are
suitable for viewing by projection of back illumination. This high
conrast requires a much greater range of densities than are
encountered in negative materials. Transparency materials probably
have less than one stop either way for optimum quality.

Richard Knoppow
Los Angeles, CA, USA
dickburk.RemoveThis@ix.netcom.com<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Black and White film latitude ? 

"David Nebenzahl" <nobody.DeleteThis@but.us.chickens> wrote in message
news:40020046.9020204@but.us.chickens...
 > On 1/11/2004 5:26 PM Paul W. Ross spake thus:
 >
 > You should be able to get accurate exposures even with a pinhole camera.
(I
 > also have a 4x5 pinhole camera, among other sizes.) You just need to know
the
 > relative aperture, which you can easily compute from the size of the
pinhole
 > and its "focal length" (distance from film):
 >
 > rel. aperture = focal length / pinhole dia.

The problem usually is knowing the diameter of the pinhole. There are
several ways to do it (using an enlarger, a microscope, a slide projector,
etc). Some years ago I wrote about how to measure it using a cheap flat bed
scanner, here is a link to to that small article:
<a style='text-decoration: underline;' href="http://members.rogers.com/penate/diameter.htm" target="_blank">http://members.rogers.com/penate/diameter.htm</a>

Guillermo<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Black and White film latitude ? 

On 1/11/2004 8:11 PM GP spake thus:

 > "David Nebenzahl" <nobody.RemoveThis@but.us.chickens> wrote in message
 > news:40020046.9020204@but.us.chickens...
  >> On 1/11/2004 5:26 PM Paul W. Ross spake thus:
  >>
  >> You should be able to get accurate exposures even with a pinhole camera.
 > (I
  >> also have a 4x5 pinhole camera, among other sizes.) You just need to know
 > the
  >> relative aperture, which you can easily compute from the size of the
 > pinhole
  >> and its "focal length" (distance from film):
  >>
  >> rel. aperture = focal length / pinhole dia.
 >
 > The problem usually is knowing the diameter of the pinhole. There are
 > several ways to do it (using an enlarger, a microscope, a slide projector,
 > etc). Some years ago I wrote about how to measure it using a cheap flat bed
 > scanner, here is a link to to that small article:
<font color=purple> > <a style='text-decoration: underline;' href="http://members.rogers.com/penate/diameter.htm</font" target="_blank">http://members.rogers.com/penate/diameter.htm</font</a>>

Well, since you broached the subject, I found the easiest way to be by viewing
the pinhole with a microscope. I just happen to have a microscope I picked up
at the local recycled-goods store for about $5; plenty good enough to get a
good look at the pinhole. I also have a couple of "gauges", which are nothing
but small lengths of wire (guitar strings) with handles: one is .010", the
other is .009" (smallest strings made). I focus on the pinhole, then stick the
"gauge" next to it (takes steady hands), then guesstimate the size of the hole
from the gauge. I figure I'm easily within .002" this way.

My latest pinhole was less than .009" and almost perfectly round.


--
Focus: A very overrated feature.

- From Marcy Merrill's lexicon at Junk Store Cameras
(http://merrillphoto.com/JunkStoreCameras.htm)<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Black and White film latitude ? 

"Robert Whitehouse" <bob.whitehouse RemoveThis @btinternet.com> wrote in message
news:bts776$ql9$1@sparta.btinternet.com...
 > We all know that colour negative film has much greater latitude than
 > reversal (slide) film, but where does your typical black and white
negative
 > film stand in this ?
 >
 > Is it closer to colour negative, or colour slide, from a latitude
 > perspective ?

In critical practice, B&W has one stop lattitude on either side of the
correct exposure. That means if you meter correctly (and know _how_ to meter
correctly), and develop to a standard you can screw up one stop. If you mean
how long a range can B&W capture, then it depends upon your needs - how
critical they are, how you print, and so-forth.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Black and White film latitude ? 

Latitude of B&W film is as high as color negatives.. The highest latitude
is found in the chromogenic B&W, such as XP2, TCN400, etc...
denny
"Robert Whitehouse" <bob.whitehouse.TakeThisOut@btinternet.com> wrote in message
news:bts776$ql9$1@sparta.btinternet.com...
 > We all know that colour negative film has much greater latitude than
 > reversal (slide) film, but where does your typical black and white
negative
 > film stand in this ?
 >
 > Is it closer to colour negative, or colour slide, from a latitude
 > perspective ?
 >
 > BW
 >
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Black and White film latitude ? 

On Sun, 11 Jan 2004 20:27:47 -0700, Tom Phillips <nospam777 DeleteThis @aol.com>
wrote:

 >Some years ago I produced a how-to on pinhole cameras. Here's a brief
 >chart on pinhole f stops and how to estimate exposure.
 >
 >http://members.aol.com/nospam777/pinhole_exposure.html

  I want a pinhole enlarging lens ! ;>))


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: Black and White film latitude ? 

RE: Tom Phillips <nospam777 DeleteThis @aol.com> wrote

 > Some years ago I produced a how-to on pinhole cameras.

Have you ever worked with a pinhole camera equipped with a
meniscus lens? Have you any source material on such an arrangment
you would recommend? Dan<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Black and White film latitude ? 

On 1/12/2004 1:49 PM Dan Quinn spake thus:

 > RE: Tom Phillips <nospam777.DeleteThis@aol.com> wrote
 >
  >> Some years ago I produced a how-to on pinhole cameras.
 >
 > Have you ever worked with a pinhole camera equipped with a
 > meniscus lens? Have you any source material on such an arrangment
 > you would recommend?

Hate to be the one to point this out, but it wouldn't be a pinhole camera
anymore with a lens of *any* type.


--
Focus: A very overrated feature.

- From Marcy Merrill's lexicon at Junk Store Cameras
(http://merrillphoto.com/JunkStoreCameras.htm)<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Black and White film latitude ? 

"Robert Whitehouse" <bob.whitehouse DeleteThis @btinternet.com> wrote:

 >Is [b&w film] closer to colour negative, or colour slide, from a latitude
 >perspective ?

Closer to color negative.

You can make a mediocre print from a negative that's been overexposed by 3
stops (or so) or underexposed by 2.

Like everything, there isn't a magic silver bullet. For any given image
that you have in mind, there's an ideal way to expose and develop the
negative. You can't deviate from this much and still obtain the ever
elusive "perfect" print.

So for critical prints, +/- half a stop, which is still a lot more latitude
than color slide.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: Black and White film latitude ?