nestor_alvarez

Joe, what a lesson. Thanks!. All the information provided is very valuable to polish my art. I have experience with reciprocity in films but not in paper. Your information will help me out in this area on papers.

Yesterday I tried to calibrate my Durst probe / meter to a negative that I printed with the right exposure / contrast according to my view. But I did not succeed. If I cannot do it after another tries I will buy an enlarger meter.

Thanks Joe regarding the recommendation to leave the print in the development tray more time instead of less. I do not have a problem with cold temperature as I live in Miami and usually what is difficult for me is getting the developer at 20C as it will normally go to 24 or 25 C alone. In order to keep it at 20 C I need to place a bag with ice into the tray and measure the temperature until it reaches 20C. I am printing basically 6x6 so f11 is two stops before maximum aperture.

I arrived at 21 sec after the second test strip were I considered the 20sec strip a little underexposed and the 22sec kind of over, so I decided 21sec.

Thanks Alan! Very practical and detailed explanation. I am currently developing as you mentioned (about 90secs) and then place in stop and fix for 1min. Most of the time the paper is face down. I also make sure that the agitation and developer temperature is 20 deg C. What I am not doing is changing the exposure time at different filter grades. I did all (from grade 1 to 5) at 21sec f11. Do you agree to change exposure time, and in that case what percentage change from grade to grade do you recommend to start with?

Thanks again for your explanation of how filters work!

Your results are surprising; what you describe should not be happening! Something is wrong! First, reviewing how variable contrast paper works (stylized view): Paper is coated with two emulsions: a low contrast emulsion sensitive mainly to green light, plus a high contrast emulsion sensitive mainly to blue light. Contrast is thus controlled by adjusting the ratio of the exposures applied to each.

 

 

A yellow filter is a blue blocker. Setting the yellow knob higher results in higher yellow filtration, thus less blue light exposes the paper. This allows the green sensitive low contrast emulsion to carry the burden. The result is a lowered contrast print.

 

 

Conversely, a magenta filter is a green blocker. Setting the magenta knob higher results in higher magenta filtration; thus less green light exposes the paper. This allows the yellow sensitive high contrast emulsion to carry the burden. The result is a higher contrast print.

 

 

If no filter is deployed, the results will be about equal exposure action in both emulsions. The finished print replicates a “normal” fixed grade #2 paper.

 

 

What could be wrong with your setup? Your notion that the filter settings prearrange the same exposure is false! All filters have what is called a “filter factor”. In other words, as you deploy more and more filtration, you also are blocking light energy. The more the filtration -- the less light the paper receives. Moving the filters induces a change in exposure. This change must be countered or under or over exposure results. We must counter filter changes just as we counter change induced by film density, enlarger height, and aperture setting. Exposure adjustments of the enlarger is an acquired skill.

 

 

What I surmise: You are developing under safelight by inspection. When you observe the print has the desired density you then transfer it to the stop and fix. This is OK but ---- contrast is also adjusted by altering the developing time. More time in the developer adds contrast. Conversely, less time delivers a flatter print. Let’s for a few weeks change your developing method. For this training period, prints are plopped into the developer face down. Don’t peek! Time the developer, I think 90 seconds or perhaps 120 seconds will work for you. Pick a time and stick to it. At the end of the predetermined developing time, plop the print in the stop and fix. This method will likely solve your dilemma. Surely it will give you a better handle on what is happening. If you are to continue doing this stuff, buy an enlarging meter, it will save you time and money.

All the rest is constant, same exposure at 21sec f11, same developer (BW-65 from Photographers Formulary), same time 90sec with same agitation at same temperature. All with Oriental Seagull VC paper

Try maximum magenta filtration on the enlarger, with no yellow at all, and certainly no Cyan.

 

If that isn't contrasty enough, then there's something else amiss somewhere.

 

An all-white print would indicate extreme under exposure.

 

Remember that those filter guides are exactly that - a guide. You should make notes and adjustments for your own apparatus and way of working.

Hello,

About 3 years ago I changed my photography to 100% analog. I installed a darkroom in the garage and the results have been quite interesting and I can see my own improvement in developing / printing.

One area which became totally frustrating is the control of contrast with the Durst AC 707. I use the table provided by Ilford papers in relation to the combination of magenta and yellow filters to reach a desired grade with VC papers. I used Ilford, Ultrafine Silver Eagle and Oriental Seagull. With all of them I get the same results: when I want to increase contrast (for example from grade 2 to grade 3) I get a print that is considerable with less contrast instead of more. I made a try from extremes (without filters, with filters at grade 1 and with filters at grade 5) and the results were amazing: the most contrasty print is the one without filters, then the one at grade 1 and the print at grade 5 is almost all white. I used the same exposure (21 sec at f11) for all of them as it is supposed that the combination of filters (between magenta and yellow) are predetermined to use the same exposure.

Any help on this area is more than appreciatted!!!

thanks, Nestor

I have just received 10 120 Ektar 100 rolls scanned from North Coast Photographic Services with a note on 3 rolls "120 Backpaper shows through image". Not all the images of these 3 rolls are affected, but the ones with a clear blue sky, it is very noticeable the word KODAK and some numbers (mainly 8 and 9). The Lab did an excellent development and scanning but some rolls ( 3 out of 10) have this problem. Anyone knowing what are the latest news regarding this?

Thanks.