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Hi All,

I just wondered if you could explain the correct procedure for determining the correct normal development time, for a specific film/developer combination. Is the development time decided both on the density of the negative and the exposure of a test print? If so, how do you decide the correct exposure of the print, given a negative of the "correct" density? I read Ansel Adams' procedure, but I'm still confused...

Thanks for your help,

Val

There are a lot of ways leading to Rome. My current method is to put step wedge into my enlarger and determining the exposure that prints density 0,75 step on a grade 2 paper to a reflection density 0,75. Subsequently I print the negative I want to test with the same exposure. If the print has to much contrast shorten the dev. time. Not enough lengthen dev. time. If the print is to dark the film must have a lower asa setting. If to light, a higher asa.

Thanks for your reply Gary. I suspected there was more than one way to do that. As soon as I will have a darkroom, I will do my own experiments, which is always a lot of fun!

This must belong in the new wet processing forum!

I hadn't heard of that step wedge method...
I am fortunate (?) to have a transmission densitometer at work, so measure the densities. There are several ways of doing this (Adams, lambrecht...).

The most sensible way I have seen is Blakemore's method of taking pictures of a towel and working out times to give you texture at different zones. This isn't too technical and is tailored to your enlarger.

Ian

zoikes wrote:This must belong in the new wet processing forum!Ian

Done!

There is a lot to find about the optimum development of the negative for further printing in the dark room. But not so much for scanning end post processing with PS. Is it possible to say how a negative should look like for scanning ? dmax - dmin ?

Paul Mitchell wrote:

zoikes wrote:This must belong in the new wet processing forum!Ian

Done!

Cheers Paul! I was going to send a message to you admins about this.

gary mulder wrote:There is a lot to find about the optimum development of the negative for further printing in the dark room. But not so much for scanning end post processing with PS. Is it possible to say how a negative should look like for scanning ? dmax - dmin ?

I would love to do that, but I don't if there's a way to get actual density value from a scanner. Independently to what actual values of Dmin and Dmax are, the range is always normalised between 0 - 255 in a 8 bit grey scale. Does anyone know how to reverse that? Though I expect it to be scanner dependant.

Val

Val,

If you have a step-wedge such as a Stouffer T2115 then you can scan that alongside the actual negative and then compare scanner readings in the negative to the scanner readings of the steps in the step wedge. I often plot a graph of the step values and their densities and then just use the graph to interpolate between the steps in the step wedge. If you have a reflective step-wedge, then you can do the same but for print density.

Best regards,

Evan

Hi Evan,

thanks, that sounds like a very simple procedure. Where do I get a Stouffer step wedge from? I found their website, but I couldn't see it on any retailer in UK...

Cheers,

Val

Valerio Trigari wrote:Hi Evan,

thanks, that sounds like a very simple procedure. Where do I get a Stouffer step wedge from? I found their website, but I couldn't see it on any retailer in UK...

Cheers,

Val

I just ordered one from http://www.rhdesigns.co.uk.

Val,

Yes I got my first step wedge from RH designs too, but recently purchased a 31 step transmissive and a 21 step reflective one directly from Stouffer in the US; I sent them an email to confirm the prices and then they can take the order by telephone.

Best regards,

Evan

I received the step wedge a couple of days ago. I didn't expect it to be so small, though it fits without any trouble in the film holder of my scanner. Hopefully it'll help me with my experiments.

Val