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contact print exposure time



 
 
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  #1  
Old July 3rd 04, 12:19 AM
John Bartley
external usenet poster
 
Posts: n/a
Default contact print exposure time


This afternoon, having finally made a negative with proper focus, I
decided to make a contact print. I had never done this before, and I've
got to say it wasn't a lot of fun at first. I read all the stuff on the
web that I could find about making test strips etc..but when I tried it,
all I got was solid black prints. Figuring that I was overexposing, I
searched with no success to try and find out what size of bulb to use
for exposing the paper. In error, I decided that a nice bright bulb
would be the way to go, so armed with a 100watt "cool white" gooseneck
lamp, I boarded up the bathroom (again!) and started to experiment. It
took eight tries to get the first useable print, and that was obtained
by flicking the lamp "on and off" twice with no stop in between. That
print being a bit too dark still, I tried again, and three tries later I
had a very nice useable print (scan to follow). This 100 watt bulb at
about 15" above the glass plate that held the negative and paper flat
took an exposure time of ??? It was just on and off again as fast as I
could flick the switch, almost like a flash bulb. I wonder if any out
there has any experience with "wattage" vs "exposure duration" times and
could lend some advice?

cheers again


--
regards from ::

John Bartley
43 Norway Spruce Street
Stittsville, Ontario
Canada, K2S1P5

( If you slow down it takes longer
- does that apply to life also?)
  #2  
Old July 3rd 04, 12:50 AM
f/256
external usenet poster
 
Posts: n/a
Default contact print exposure time


"John Bartley" wrote in message
m...

This afternoon, having finally made a negative with proper focus, I
decided to make a contact print. I had never done this before, and I've
got to say it wasn't a lot of fun at first. I read all the stuff on the
web that I could find about making test strips etc..but when I tried it,
all I got was solid black prints. Figuring that I was overexposing, I
searched with no success to try and find out what size of bulb to use
for exposing the paper. In error, I decided that a nice bright bulb
would be the way to go, so armed with a 100watt "cool white" gooseneck
lamp, I boarded up the bathroom (again!) and started to experiment. It
took eight tries to get the first useable print, and that was obtained
by flicking the lamp "on and off" twice with no stop in between. That
print being a bit too dark still, I tried again, and three tries later I
had a very nice useable print (scan to follow). This 100 watt bulb at
about 15" above the glass plate that held the negative and paper flat
took an exposure time of ??? It was just on and off again as fast as I
could flick the switch, almost like a flash bulb. I wonder if any out
there has any experience with "wattage" vs "exposure duration" times and
could lend some advice?


When I did contact prints using a similar setup, I placed a 15watts bulb at
about 4 feet from the table and I even added a dimmer switch, so I could dim
the bulb even more to get 20 secs or so of printing time (I did some dodging
and burning sometimes). With exposure times this long you can count (1,
1001, 2, 2002, 3, 2003, etc or whatever you prefer) and have a good idea of
how many seconds of exposure you are giving.

Guillermo


  #3  
Old July 3rd 04, 01:44 AM
John Bartley
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Posts: n/a
Default contact print exposure time

Nick Zentena wrote:

The problem is you've got at least a third variable. That is the distance
the bulb is from the paper. 100 watts is likely going to be way too
powerfull unless the bulb is quite distant from the paper. My 4x5 enlarger
uses a 150 watt bulb but the lens can easily be stopped down to F/11. Which
would cut the light by a factor of 128(I think). Use a smaller bulb. BTW I
mean the lens would be F/11 or smaller in use. The lens will stop down
further.

Fourth variable. The paper. Different papers will have different
speeds. I'm assuming you're using an enlarging paper.

Nick



Hi Nick and Guillermo,

Thank you for the replies. They are EXACTLY what I needed.

Nick, I don't really know what "enlarging" paper is. I am using Ilford
MGIV RC 5x7 in a satin finish. I have never really liked a glossy print,
but I may try glossy paper on my next purchase, and reprint some
negatives just to compare between satin and glossy.

Nick & Guillermo, If I understand what you're saying, the bulb size can
be quite small then I guess, and I gather that up to a certain point
(that point to be determined by experiment) the diminishing amount of
light produced by a smaller bulb can be made up for by increased
exposure times. I guess also that the higher (up to a point) that the
bulb is above the exposure plane, the more even the light is, and will
appear to be perpendicular to the paper/negative combination rather than
be at a slight angle which is what would be seen when the bulb is closer
to the plane of the paper? I would think that there would be some loss
of crispness as you get closer to the paper with the bulb?

Last question : Has any one seen any difference between a coated (soft
white) bulb and a clear glass bulb in the print quality?

cheers

--
regards from ::

John Bartley
43 Norway Spruce Street
Stittsville, Ontario
Canada, K2S1P5

( If you slow down it takes longer
- does that apply to life also?)
  #4  
Old July 3rd 04, 01:45 AM
John Bartley
external usenet poster
 
Posts: n/a
Default contact print exposure time

John Bartley wrote:


Hi Nick and Guillermo,

Thank you for the replies. They are EXACTLY what I needed.



Ooops - a scan of the better print can be seen at :
http://www3.sympatico.ca/oldrad/Phot...0040702-cp.png

cheers

--
regards from ::

John Bartley
43 Norway Spruce Street
Stittsville, Ontario
Canada, K2S1P5

( If you slow down it takes longer
- does that apply to life also?)
  #5  
Old July 3rd 04, 02:12 AM
Nick Zentena
external usenet poster
 
Posts: n/a
Default contact print exposure time

John Bartley wrote:
took an exposure time of ??? It was just on and off again as fast as I
could flick the switch, almost like a flash bulb. I wonder if any out
there has any experience with "wattage" vs "exposure duration" times and
could lend some advice?



The problem is you've got at least a third variable. That is the distance
the bulb is from the paper. 100 watts is likely going to be way too
powerfull unless the bulb is quite distant from the paper. My 4x5 enlarger
uses a 150 watt bulb but the lens can easily be stopped down to F/11. Which
would cut the light by a factor of 128(I think). Use a smaller bulb. BTW I
mean the lens would be F/11 or smaller in use. The lens will stop down
further.

Fourth variable. The paper. Different papers will have different
speeds. I'm assuming you're using an enlarging paper.

Nick
  #6  
Old July 3rd 04, 03:21 AM
Tom
external usenet poster
 
Posts: n/a
Default contact print exposure time

With contact paper like Azo we used a 15 watt bulb only a few inchs away from
the negative for 5 seconds or so. Enlarging paper like Ilford Multigrade, or
Kodak Polymax are maybe a 100 times faster than Azo.

Usually when making contact prints (contact sheets) with enlarging paper we use
the enlarger as a light source running the head up to about where it covers
11x14 or so and setting the f=stop to maybe f/16. If you do not have an enlarger
you might want to try a 5-15 watt bulb 2-4 feet from the negative.

BTW, when using an enlarger as the light source you can filter the light with a
variable contrast filter to adjust the paper grade. All contact paper I ever
heard of was graded paper, and most that is still available (very hard to find)
is only available in one or two grades now.

--

John Bartley wrote:

This afternoon, having finally made a negative with proper focus, I
decided to make a contact print. I had never done this before, and I've
got to say it wasn't a lot of fun at first. I read all the stuff on the
web that I could find about making test strips etc..but when I tried it,
all I got was solid black prints. Figuring that I was overexposing, I
searched with no success to try and find out what size of bulb to use
for exposing the paper. In error, I decided that a nice bright bulb
would be the way to go, so armed with a 100watt "cool white" gooseneck
lamp, I boarded up the bathroom (again!) and started to experiment. It
took eight tries to get the first useable print, and that was obtained
by flicking the lamp "on and off" twice with no stop in between. That
print being a bit too dark still, I tried again, and three tries later I
had a very nice useable print (scan to follow). This 100 watt bulb at
about 15" above the glass plate that held the negative and paper flat
took an exposure time of ??? It was just on and off again as fast as I
could flick the switch, almost like a flash bulb. I wonder if any out
there has any experience with "wattage" vs "exposure duration" times and
could lend some advice?

cheers again


  #7  
Old July 3rd 04, 03:22 AM
joe smigiel
external usenet poster
 
Posts: n/a
Default contact print exposure time



John Bartley wrote:
....

Nick, I don't really know what "enlarging" paper is. I am using Ilford
MGIV RC 5x7 in a satin finish. I have never really liked a glossy print,
but I may try glossy paper on my next purchase, and reprint some
negatives just to compare between satin and glossy.

...


John,

Ilford MG IV RC is an enlarging paper as are most current photographic
papers.

A true contact paper is much slower and you might get away with the
higher wattage bulb with them. Most of them are fiber-based (not RC)
papers. Kodak makes AZO and I believe Bergger or Forte have recently
resurrected a contact paper. (Google Michael Smith for AZO info.)

Another choice is Centennial printing-out-paper (POP), available in both
fiber and RC flavors (from Bostick and Sullivan as well as Chicago
Albumen Works). This paper is similar to the old discontinued Kodak
Studio Proof paper. It can be printed outdoors using the sun or inside
with a strong UV source. The image appears directly with exposure
needing no development. To keep the image from further darkening (which
eventually renders it useless) the paper is rinsed, toned, fixed and washed.

I believe most enlarging papers (developing-out-papers or DOP) will also
produce a printed-out image as well if you follow the same general
procedure as a true POP material. However, I think they must be
loaded/unloaded under safelight conditions into the contact frame
because of their higher speed (unlike POP which can be loaded under
subdued tungsten lighting) and if you skip the development step and just
fix and wash the print, you will have a stable image. I've never tried
this so I don't know if the resulting image would have any quality with
a DOP processed this way. But, my favorite silver paper is Centennial
with AZO second.

You also might want to give the Ilford "pearl" surface a try. The satin
surface never reaches the same maximum dark tone as the pearl or glossy
and thus it appears much lower in contrast and overall weaker in tonal
range IMO. Pearl is in-between satin and glossy in terms of apparent
maximum density and depth. Many people prefer this surface over glossy
since it still has a lustered surface yet lacks the reflecting shiny
smooth surface of glossy RC. BTW, an RC glossy paper has a much more
distractng surface than a similar air-dried fiber-based glossy paper IMO.

Joe

(Change the vOwEl in my email address to reply to me directly.)

  #8  
Old July 3rd 04, 04:06 AM
f/256
external usenet poster
 
Posts: n/a
Default contact print exposure time


"John Bartley" wrote in message
...
Nick Zentena wrote:

Last question : Has any one seen any difference between a coated (soft
white) bulb and a clear glass bulb in the print quality?


I wouldn't use clear glass bulbs, their light distribution is not even.

Guillermo
(also in Ontario)


  #9  
Old July 3rd 04, 05:25 AM
John
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Posts: n/a
Default contact print exposure time

On Fri, 2 Jul 2004 20:12:20 -0500, Nick Zentena
wrote:

Fourth variable. The paper. Different papers will have different
speeds. I'm assuming you're using an enlarging paper.

Nick


Try Azo . And that 100 watt bulb won't seem so bright.


Regards,

John S. Douglas, Photographer - http://www.darkroompro.com
Please remove the "_" when replying via email
  #10  
Old July 3rd 04, 12:21 PM
Richard Knoppow
external usenet poster
 
Posts: n/a
Default contact print exposure time


"John Bartley" wrote in message
m...

This afternoon, having finally made a negative with proper

focus, I
decided to make a contact print. I had never done this

before, and I've
got to say it wasn't a lot of fun at first. I read all the

stuff on the
web that I could find about making test strips etc..but

when I tried it,
all I got was solid black prints. Figuring that I was

overexposing, I
searched with no success to try and find out what size of

bulb to use
for exposing the paper. In error, I decided that a nice

bright bulb
would be the way to go, so armed with a 100watt "cool

white" gooseneck
lamp, I boarded up the bathroom (again!) and started to

experiment. It
took eight tries to get the first useable print, and that

was obtained
by flicking the lamp "on and off" twice with no stop in

between. That
print being a bit too dark still, I tried again, and three

tries later I
had a very nice useable print (scan to follow). This 100

watt bulb at
about 15" above the glass plate that held the negative and

paper flat
took an exposure time of ??? It was just on and off again

as fast as I
could flick the switch, almost like a flash bulb. I wonder

if any out
there has any experience with "wattage" vs "exposure

duration" times and
could lend some advice?

cheers again


--
regards from ::

John Bartley
43 Norway Spruce Street
Stittsville, Ontario
Canada, K2S1P5

For enlarging paper contact printing is most conveniently
done using the enlarger for a light source. Exposure time
will be whatever you get with the head at the same height
for enlarging. If you are using a separate light source it
will have to be very low power. I would start with something
like a 7.5 watt night light bulb in a small reflector. You
can also rig a cardboard holder for variable contrast
filters to fit a small reflector or a Kodak "Beehive" type
safelight holder. Experiment with distance, start with a
couple of feet. Exposure times should run between 15 and 30
seconds to be controlable.
Back in the bad old days, when contact printing was
routine and done in quantity, each manufacturer of paper had
at least one contact speed paper, Kodak had three for
pictorial purposes and a couple of others for graphics use.
These papers differ from enlarging papers only in speed. A
medium speed contact paper is about 1/100th the speed of a
medium speed enlarging paper. The only one I know of left on
the market is Kodak Azo. This is a neutral tone paper. Its
speed is such that a good source is a 60 watt to 100 watt
lamp in a diffusing reflector at a couple of feet for 15 to
30 second exposures. When contact printing was done
routinely multiple lamp printing boxes were available. The
more elaborate ones had individual switches on the lamps for
compensating for unevenly exposed negatives. I have a 1950's
vingage 10x10 inch printer with 39 Argon lamps, each with
its own switch. The usual studio printing box had from four
to six lamps in it.
Enlarging paper works perfectly well for contact printing
provided you have a suitable light source. Despite the
reputation Azo has for being "magic" I think equally as good
prints can be made on good enlarging paper.
Its curious, when I started out in photography contact
printing was the introduction to printing, printing frames
were cheap, enlargers expensive, so we contact printed.


--
---
Richard Knoppow
Los Angeles, CA, USA



 




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