Testing Some New Film (Shanghai 8x10)--How I Do It...

[ic-racer]

As you see I used my Wejex sensitometer for this test. When I did the "Great Sensitometer Shootout" I tried not to show favoritism. But, when I actually need to make a control strip, there were some reasons I choose the Wejex.

The Wejex has a un-frosted very low wattage bulb that is not likely to blacken like an enlarger bulb. The frosted plastic is just below the step wedge.
The Wejext is timed with a stepper motor and rotating disk shutter. This is unlikely to ever change the exposure time unless the Hertz of my electrical line changes
The step wedge is permenently affixed in the machine, so I don't need to worry about getting it in the middle of the field or anything like that.
The Wejex is made by Tobias, who also make the matching sensitometer, so the patches fit easily under the measuring reticle.
The Wejex exposure is ONE SECOND which is closer to the exposure times used in large format photography than the flash duration of the EG&G.

When I replaced the flash tube in my EG&G there was a large increase in output. So the lamp does get dimmer with age (a known effect, shown in the EG&G manual).
There is no Thyrisotor timing mechanism on the EG&G. The flash output is always the result of complete capacitor discharge and the exposure time is related to the time constant of the capacitors and the internal resistance (ESR). I hope mine are still good, as replacements would be difficult to source.

 

[Andrew O'Neill]

Here is a chart that I have been using for a few years. It's in Chinese but it's not difficult...The first three columns show: metred time; compensated time; reduction of development time. The chart goes from 1 second to 100. I have it on my phone for reference. It's right up there with the worst reciprocity characteristics of any film that I have used...but that doesn't stop me from using this film as it is quite nice.

 

[ic-racer]

Thanks for posting reciprocity info. To answer the question earlier in the thread, NO, I don't have a system to measure and compare reciprocity failure of films at this time.
I don't know if Bull Burk does.

The EG&G is actually designed to test failure of reciprocity, but at the other end of the scale; very short exposure reciprocity failure. But I have never used it for that.

 

[Bill Burk]

I haven’t tested reciprocity law failures. Like your sensitometer, my EG&G has 1/100th second, 1/1000th second and 1/10,000th second times. There’s a model that also does 1/100,000th second.

It would be fun to setup a test for the longer exposures. Probably start with an “enlarger—>sensitometer” with a low wattage incandescent bulb on a voltage regulator.

 

[Raghu Kuvempunagar]

Here is a chart that I have been using for a few years.

Very useful. Thanks.

I have dabbled with Shanghai GP3 and found it good. I've made some slides in 4x5 format using reversal processing. I've also enlarged 35mm slides on 4x5 sheets, reversal processed and produced slides. In this context I've a general question on reciprocity failure. Do the reciprocity characteristics of a b&w film remain the same when it is used as a reversal film?

 

[Bill Burk]

Good question. Is the advice to deal with reciprocity law failure different when doing reversal development?

I don’t know, but I think it’s characteristic of the film itself so probably no difference whether developing reversal or normal.

I checked my references, Mees, Todd-Zakia and Le Clerc and found no mention of it.

But wow what studies have been done and what ways to present the data! I like the 3-D model IX-racer posted earlier.

The simplest presentation of results though, are the charts giving advice to adjust exposure and development for different exposure times.

Especially useful is shared experience based information like the chart Vaughn gave his students that Michael
Kenna gave him.

 

[ic-racer]

To link this thread to the "RESULTS" thread, below is the link to the prints made from the Shanghai film exposed using information gained using the process described in this thread:

https://www.photrio.com/forum/threads/a-year-with-shanghai-8x10-film.183060/

 

[Vaughan Bromfield]

Thanks for posting this, I have just started using Shanghai GP3 100 in 35mm, 4x5 and 5x7 format. I understand the 35mm film may be different from the sheet sizes, but ut was cheap and easy to test with. My first tests in HC1101+31 indicate it has grain and sharpness slight less than Tri-X and HP5 Plus, which are 400 ISO.

There is a trap for young players with the Shanghai sheet film (at least the boxes I have): the notch is on the BOTTOM right, not the top right like most other sheet films from Kodak or Ilford.

 

[howardpan]

There is a trap for young players with the Shanghai sheet film (at least the boxes I have): the notch is on the BOTTOM right, not the top right like most other sheet films from Kodak or Ilford.

I have been using Shanghai GP3 for a while and this does not fit with my experience. I wonder if anyone concurs with Vaughan.

 

[Vaughan Bromfield]

I just opened a box of 4x5 today, which I ordered from HK a month or two ago (so it is as fresh as I'm likely to get here in Australia). A photo of the data sheet is attached below, the key instruction being:

"Taking the films by your right hand, when you touch the "U" shape notch in the films lower right, the film side facing up is the photosensitive surface."

UPDATE: the instructions are incorrect, the notch should be in the upper right.

 

[ic-racer]

My last batch of Shanghai had some pieces with notches at both corners. My images came out fine, exposed through the back of the film, they were just backwards.

 

[Vaughan Bromfield]

Here is one for the text book: I just did a quick test with two sheets of 4x5, one with the notch down (as per the instructions) and one with the notch up (the usual convention for Kodak and Ilford). Guess what: the instructions are wrong, I've been exposing through the back of the film. Luckily only half a dozen sheets so far.

So for the record, the notch for Shanghai sheet film is the same as Kodak and Ilford. The instructions provided with the film are incorrect.

 

[MattKing]

I can't resist, even if I know I should.
Is it because in Australia you are working upside down?
Hope the film works great for you!

 

[alanrockwood]

Here is a chart that I have been using for a few years. It's in Chinese but it's not difficult...The first three columns show: metred time; compensated time; reduction of development time. The chart goes from 1 second to 100. I have it on my phone for reference. It's right up there with the worst reciprocity characteristics of any film that I have used...but that doesn't stop me from using this film as it is quite nice.

View attachment 236895

I realize it's been about a year and a half since your post was made, but can you comment more on the meaning of the third column in the table? You said it gives the reduction of development time, but what exactly does the number mean? Is it the percent reduction in development time?

 

[Andrew O'Neill]

I realize it's been about a year and a half since your post was made, but can you comment more on the meaning of the third column in the table? You said it gives the reduction of development time, but what exactly does the number mean? Is it the percent reduction in development time?

% in reduction of your normal development time.

 

[Mark Crabtree]

Here is one for the text book: I just did a quick test with two sheets of 4x5, one with the notch down (as per the instructions) and one with the notch up (the usual convention for Kodak and Ilford). Guess what: the instructions are wrong, I've been exposing through the back of the film. Luckily only half a dozen sheets so far.

So for the record, the notch for Shanghai sheet film is the same as Kodak and Ilford. The instructions provided with the film are incorrect.

Just in case nobody noticed, the instructions are not wrong, just poorly worded. Same position as everyone else.

 

[alanrockwood]

% in reduction of your normal development time.

Thanks.