Magenta filter on CLS 66 defective or me noob ?

[alex645]

Hi, today I was tryin to do some enlargment with my new durst 601 with CLS 66 colour head, I 've made my test strips, found the best timing for the highlights and the prints were ok. but when I tried to add some magenta to have some more shadows, the prints started turning very pale, the more magenta I was adding the more the prints turned paler: with 50 M the image was barely visible, with 80 it almost disappeared. Do I need to change exposure when I add magenta? I don't remember doing this with the condenser head. Or my M filters is defective ? THanks,
alex

[Ian Grant]

That's entirely normal the filter has a density so the more you dial in the longer you need to expose for. There's a chart on the Ilford website.

See here

Ian

[alex645]

many THanks ! I was just wondering if there's a rule of thumb to add the corret exposure when changing filtration, in the Ilford leaflet there's only a chart for the Aristo head .. I'll try to start with that one

[Ian Grant]

Somewhere I have the original chart for a Durst head with the exposure correction, if I find it tonight I'll scan it tomorrow and post it.

The Aristo figures are for Multigrade filters with a Cold light source which are quite different.

Ian

[alex645]

Somewhere I have the original chart for a Durst head with the exposure correction, if I find it tonight I'll scan it tomorrow and post it.

The Aristo figures are for Multigrade filters with a Cold light source which are quite different.

Ian

yes, from grade 2 to 3 the chart tell to multiply exposure for 0.76 .. and my paper is already blank! It's strange that the leaflet have a section on Durst enlarger but they don't even say that you have to change exposure ! thanks again Ian

[ic-racer]

To be able to not change exposure you need to be using a filtration table that has combined Yellow and Magenta settings.

[ic-racer]

in the Ilford leaflet there's only a chart for the Aristo head ..

?? Scroll down to the DURST table. It should work well with your enlarger. (Upper right of page 3)

[alex645]

it is the Y + M filtration chart. I was looking for exposure correction with M only. But I can figure out that if you don't want to change the exposure every time you change filtration then you've got to use the Y+M

[Ian Grant]

I had no luck looking, there were no old Multigrade data-sheets in my box of Ilford data. I'm sorting out books etc that are in storage and know I do have a chart with the exposure factors, I saw it a few weeks ago.

However you really need to be doing test strips anyway at your chosen contrast/filtration. Even knowing the exposure at one Grade (or no filtration) you can't really predict or calculate how a print will turn out at another contrast grade unless you have a lot of experience. At best it'll get you in the ball park.

Ian

[ic-racer]

If for some reason you only want to use a single filter at a time, then you will have to make your own table, as that is not a common way to do it. It is not that hard to make the table, but it is easiest if you have a transmission step wedge (less than $20).

Make a table like this 100Y, 75Y, 50Y, 30Y, 0, 30M, 50M, 75M, 100M and make step wedge exposures at each setting using the same time. By matching the same gray band across each test you can get a rough idea of how much exposure change there is between any two of the settings. The step wedge will show one-half stop increments.

I used to use a table like that for 20 years. Then I started using the Ilford recommended Durst and Omega Y/M settings and found it much much easier and can't see going back. The Ilford table works very well for me with no additional tweaking.