TMax100 ; reciprocity characteristics

[fw1]

Does anyone have a reliable guide as to the reciprocity corrections required for TMax100 for exposures > 1 second ; comments on both exposure compensation and development would be appreciated.

[scott_jones4]

Hi FW,

 

<p>

 

The Kodak web site has the short table for reciprocity failure which I

suspect is written on your box, but here is the link:

http://www.kodak.com/global/en/professional/support/techPubs/f32/f32b.

shtml#1153016

 

<p>

 

There is no detailed curve like they have for Tri-X that I can find.

 

<p>

 

Scott

[david_goldfarb]

Kodak's guideline is no correction needed up to 10 seconds. Steve

Simmons has a chart for TMX in _Using the View Camera_ which is

somewhat more conservative, but TMX has such a wide tonal range and

long straight curve that less compensation is needed than for

traditional films.

[bob_moulton]

Indicated actual

Is 1

2

[bob_moulton]

1 s=1

2s=2.5

4s=6

8s=11

15s=25

30s=54

60s=1:55

1m=1:55

2m=4:00

4M=8:30

8M=17:30

15M=36:00

30M=1H30M

60M=3H30M

 

<p>

 

Hope this guide helps.

Bob

[ernie_gec]

Bob:

 

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I'm very interested in your adjusted figures. They don't correspond

at all to the Kodak supplied data & I'm wondering what kind of testing

underlies these numbers.

 

<p>

 

ernie

[michael_kadillak3]

Bobs numbers are on the money as they are nearly identical to my set

compiled from Howard Bond (Jan/Feb 2001 Photo Techinques pg 54) and

Bruce Barnbaum ("The Art Of Photography" Second Edition pg 80).

Barnbaum feels that a N + 1/2 is the necessary adjustment.

Considering the age old axiom that the answer can only be as accurate

as the least accurate input, my objective is to get in the ballpark.

Should entensive reciprocity be something that you encounter

regularly in your photography, there is always the densitometer.....

 

<p>

 

The limited amount of correcting I have done for reciprocity using

the factor table listed by Bob with these factors seems to be fine.

Out of habit, I take anything Kodak says about these factors and the

darkroom with a grain of salt.

[fw1]

Bob - those factors are very helpful - what development adjustments

do you make, if any? Regards

[robb_reed]

Mike,

 

<p>

 

Is that N+1 or N+2? Or do you mean N + 5% (which would = N+1/2)

 

<p>

 

Thanks,

 

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Robb Reed

[michael_kadillak3]

The reference to Barnbaums N + 1/2 associated with his reciprocity

correction deserves further clarification. In essence, he is stating

that because of the extended exposure, the net effect on the negative

is an N + 1/2 with normal development. If you desire a N development,

then you must give the negative a N - 1/2 to compensate for the

contrast increased during the long exposure. Hope this helps.

[fw1]

Michael ; I think that you have partly answered my question. In other

words, at a normal EI (for N), and with normal development, if the

exposure is greater than 1s, I should end up with N + 1/2 contrast in

the negative. Knowing this, it should then be possible to place

shadows and highlights and determine what development is required -

despite the inherent increased contrast, I suppose it is conceivable

in a dimly lit and low contrast situation that you would choose to

extend rather than reduce development - in fact, I can imagine this

type of situation quite easily. Is my thinking right?<p>

 

Now, does the degree of contrast change as exposure increases - i.e.

once you get beyond a certain time, does normal development then

deliver a N+1, or N+2 without adjustment? Together with Bob's table,

such knowledge would be most useful.