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Deconfusion request -B&W film exposure latitude



 
 
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  #1  
Old November 17th 03, 09:45 PM
Alan Browne
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Default Deconfusion request -B&W film exposure latitude



How much exposure latitude can I get with B&W films? Worst and best
please?


Thanks,

Cheers,
Alan
--
e-meil: there's no such thing as a FreeLunch.

  #2  
Old November 17th 03, 11:20 PM
Michael A. Covington
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Default Deconfusion request -B&W film exposure latitude

"Alan Browne" wrote in message
...


How much exposure latitude can I get with B&W films? Worst and best
please?


It depends on how you develop it. By underdeveloping, you lower the
effective speed and increase the exposure latitude. By overdeveloping, you
do the opposite.

That's for conventional black-and-white films.

If you need extreme exposure latitude, I suggest a C-41 (color process)
black-and-white film such as Kodak Black & White Plus 400 or T400CN. The
latitude is something like 1 stop under, 5 stops over. Others will have
more exact answers.


  #3  
Old November 18th 03, 10:43 AM
Norman Worth
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Default Deconfusion request -B&W film exposure latitude

It depends a lot on the film. The Kodak TMax films are extraordinary, and
sometimes hard to print as a result. The old Verichrome Pan was designed
for non-adjustable cameras and also gave remarkable results over a wide
range of exposure. Modern films, like FP4+, are not quite so wide. You can
get a good idea from looking at the film's characteristic curve. Determine
the exposure range (log E) for which you get a useful change in density.
Most outdoor scenes require about seven stops (delta log E of 2.15) to
capture a good likeness of the image. Any extra available from the film is
the true "latitude". Note however that many scenes require a much shorter
exposure range, so the latitude can be greater (if you adjust the print
contrast).
"Alan Browne" wrote in message
...


How much exposure latitude can I get with B&W films? Worst and best
please?


Thanks,

Cheers,
Alan
--
e-meil: there's no such thing as a FreeLunch.



  #4  
Old November 18th 03, 05:53 PM
Alan Browne
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Default Deconfusion request -B&W film exposure latitude

Hi Norman,

Could you answer the following: For a film like TMax (or any other if
you prefer) what is the latitude range in stops. Assume metering for
18% grey and the film is exposed as rated.

I'm not interested (at this point) in what can be printed, I'm
interested in what can be recorded.

Thanks,
Alan.

Norman Worth wrote:

It depends a lot on the film. The Kodak TMax films are extraordinary, and
sometimes hard to print as a result. The old Verichrome Pan was designed
for non-adjustable cameras and also gave remarkable results over a wide
range of exposure. Modern films, like FP4+, are not quite so wide. You can
get a good idea from looking at the film's characteristic curve. Determine
the exposure range (log E) for which you get a useful change in density.
Most outdoor scenes require about seven stops (delta log E of 2.15) to
capture a good likeness of the image. Any extra available from the film is
the true "latitude". Note however that many scenes require a much shorter
exposure range, so the latitude can be greater (if you adjust the print
contrast).
"Alan Browne" wrote in message
...


How much exposure latitude can I get with B&W films? Worst and best
please?


Thanks,

Cheers,
Alan
--
e-meil: there's no such thing as a FreeLunch.





--
e-meil: there's no such thing as a FreeLunch.

  #5  
Old November 18th 03, 06:25 PM
Alan Browne
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Default Deconfusion request -B&W film exposure latitude


Okay, my confusion remains.

How many stops can I get onto the film. For example if I meter for a
specific exposure and the scene has detail going 6 stops above and 6
stops below, how much will I actually record?

Is this a question of 'range' rather than latitude?

Cheers,
Alan.


Norman Worth wrote:

It depends a lot on the film. The Kodak TMax films are extraordinary, and
sometimes hard to print as a result. The old Verichrome Pan was designed
for non-adjustable cameras and also gave remarkable results over a wide
range of exposure. Modern films, like FP4+, are not quite so wide. You can
get a good idea from looking at the film's characteristic curve. Determine
the exposure range (log E) for which you get a useful change in density.
Most outdoor scenes require about seven stops (delta log E of 2.15) to
capture a good likeness of the image. Any extra available from the film is
the true "latitude". Note however that many scenes require a much shorter
exposure range, so the latitude can be greater (if you adjust the print
contrast).
"Alan Browne" wrote in message
...


How much exposure latitude can I get with B&W films? Worst and best
please?


Thanks,

Cheers,
Alan
--
e-meil: there's no such thing as a FreeLunch.





--
e-meil: there's no such thing as a FreeLunch.

  #6  
Old November 18th 03, 08:36 PM
David Meiland
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Posts: n/a
Default Deconfusion request -B&W film exposure latitude

Alan Browne wrote:


Okay, my confusion remains.

How many stops can I get onto the film. For example if I meter for a
specific exposure and the scene has detail going 6 stops above and 6
stops below, how much will I actually record?

Is this a question of 'range' rather than latitude?

Cheers,
Alan.


Norman Worth wrote:

It depends a lot on the film. The Kodak TMax films are extraordinary, and
sometimes hard to print as a result. The old Verichrome Pan was designed
for non-adjustable cameras and also gave remarkable results over a wide
range of exposure. Modern films, like FP4+, are not quite so wide. You can
get a good idea from looking at the film's characteristic curve. Determine
the exposure range (log E) for which you get a useful change in density.
Most outdoor scenes require about seven stops (delta log E of 2.15) to
capture a good likeness of the image. Any extra available from the film is
the true "latitude". Note however that many scenes require a much shorter
exposure range, so the latitude can be greater (if you adjust the print
contrast).
"Alan Browne" wrote in message
...


How much exposure latitude can I get with B&W films? Worst and best
please?


Thanks,

Cheers,
Alan




Alan,

It's a function of not only the film and exposure but the processing.
From my casual reading of it over the years, the best you can get is
about ten stops, and I think a typical range is more like 7 stops. It
has everything to do with your particular combination of film,
exposure, and chemistry. For the extremes you want you'll need to pull
the film, maybe overexpose two stops and underdevelop two stops,
processing for longer than normal with a more dilute developer.
---
David Meiland
Friday Harbor, WA
http://davidmeiland.com/

**Check the reply address before sending mail
  #7  
Old November 18th 03, 08:43 PM
Mark A
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Default Deconfusion request -B&W film exposure latitude

Okay, my confusion remains.

How many stops can I get onto the film. For example if I meter for a
specific exposure and the scene has detail going 6 stops above and 6
stops below, how much will I actually record?

Is this a question of 'range' rather than latitude?

Cheers,
Alan.

Unless you are metering an illuminated light source (or reflection from an
illuminated light source) the maximum metered range of a scene is about 10
stops total (usually at high altitude or desert areas), and 7-8 stops is
more likely to be observed in areas of normal humidity. For scenes that are
not in bright sunshine, the range is obviously less.

How much you can fit on film depends on development time (which determines
negative contrast). The less the development time, the greater range of
scene reflectance that will fit on the film.


  #8  
Old November 19th 03, 12:40 AM
Michael A. Covington
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Default Deconfusion request -B&W film exposure latitude


"Alan Browne" wrote in message
. ..

Okay, my confusion remains.

How many stops can I get onto the film. For example if I meter for a
specific exposure and the scene has detail going 6 stops above and 6
stops below, how much will I actually record?

Is this a question of 'range' rather than latitude?


Yes, and you can read it off the film's characteristic curve. That's why
they give those curves in the data sheet. Each unit (from 2.0 to 3.0 for
instance) is a factor-of-10 brightness range.

It depends on development. You get more range if you underdevelop.


  #9  
Old November 19th 03, 12:46 AM
Michael A. Covington
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Default Deconfusion request -B&W film exposure latitude

Here's a worked-out example using data from:

http://www.kodak.com/global/en/profe...16/f4016.jhtml

T-Max 100 film ("new" variety, 100TMX), developed in D-76 in a small tank
for 6 minutes at 68 F, has a plotted range from -2.0 to nearly +1.0 and is
not topping out at the right-hand end. I estimate its usable range is
probably 3.5 log exposure units, with a maximum density of about 2.2 (which
you should be able to scan or print).

3.5 log exposure units = a factor of 10^(3.5):1 = 3000:1, roughly = 12
stops, roughly.

You can develop the film even less and get an even wider range.

When the film is underdeveloped this much, you should set your meter at 50
or 25 rather than 100. Experimentation will be in order.


  #10  
Old November 19th 03, 04:48 PM
Alan Browne
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Posts: n/a
Default Deconfusion request -B&W film exposure latitude



Michael A. Covington wrote:

Here's a worked-out example using data from:

http://www.kodak.com/global/en/profe...16/f4016.jhtml

T-Max 100 film ("new" variety, 100TMX), developed in D-76 in a small tank
for 6 minutes at 68 F, has a plotted range from -2.0 to nearly +1.0 and is
not topping out at the right-hand end. I estimate its usable range is
probably 3.5 log exposure units, with a maximum density of about 2.2 (which
you should be able to scan or print).

3.5 log exposure units = a factor of 10^(3.5):1 = 3000:1, roughly = 12
stops, roughly.

You can develop the film even less and get an even wider range.

When the film is underdeveloped this much, you should set your meter at 50
or 25 rather than 100. Experimentation will be in order.



Thanks Michael.

Alan
--
e-meil: there's no such thing as a FreeLunch.

 




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