LPL Dichro Head Filter Settings for B&W Contrast Grades

[waynecrider]

Does anyone know where a chart exist for the filter settings for different
b&w contrast grades using the LPL dichro head? I believe the head uses kodak's values.

 

[Nick Zentena]

Which paper/papers? Odds are the paper supplier has some suggestions on what to use.

 

[ggriffi]

Does anyone know where a chart exist for the filter settings for different
b&w contrast grades using the LPL dichro head? I believe the head uses kodak's values.

Wayne,

If you have Anchell's book, there are some listing for various papers, but if I recall ( I don't have the book with me right now) I don't think there is anything on LPL's.

g

 

[Seele]

In an old Ilford Multigrade IV data booklet, it says that the LPL uses the Kodak system; two methods were given using a single filter for maximum light transmission (requiring exposure compensation) and two filters to approximate the Multigrade filters.

Single Filter Method

Filter No Setting

00 199Y
0 90Y
1/2 70Y
1 50Y
1 1/2 30Y
2 0
2 1/2 5M
3 25M
3 1/2 50M
4 80M
4 1/2 140M
5 199M

Two Filter Method (equals to using Ilford Filters)

00 162Y 0M
0 90Y 0M
1/2 78Y 5M
1 68Y 10M
1 1/2 49Y 23M
2 41Y 32M
2 1/2 23Y 42M
3 23Y 56M
3 1/2 15Y 75M
4 6Y 102M
4 1/2 0Y 150M

It is perhaps odd to see that at the extremes of filtration, where one filter is needed, the single filter and two-filter methods vary somewhat. Ilford stated that for the two-filter method it is impossible to achieve the equivalence of No.5.

Later Ilford publications do not recommend using dichroic head settings for this purpose and do not publish this chart.

Good luck!

 

[Nick Zentena]

Later Ilford publications do not recommend using dichroic head settings for this purpose and do not publish this chart.

http://www.ilford.com/html/us_english/pdf/Cont.pdf

I don't see any claim not to use Dichroic heads. I see a claim that they don't get high contrast but my own tests with Agfa paper showed quite high contrast.

 

[waynecrider]

Thanks!

Any idea's as to what minimal change increments are, and whether they affect each value in a two filter setting.

 

[hka]

Filtersettings

Does anyone know where a chart exist for the filter settings for different
b&w contrast grades using the LPL dichro head? I believe the head uses kodak's values.

I have calibrated the LPL for some time ago with MG IV RC paper and the filtersetting I have explored are:
00 120 12
0 103 17
0.5 84 25
1.0 68 34
1.5 59 41
2.0 50 47
2.5 45 54
3.0 40 61
3.5 36 67
4.0 32 73
4.5 25 86
5.0 17 101
5.5? 11 124

The method I followed was described in the WBM-book. I used therefore a step wedge with 31 steps.

 

[Bob Carnie]

wayne
If you get stuck , a very practical way is to take a normal negative with a large grey card in the scene, and have it printed with filters under a condensor enlarger in the 1/2 grade filters from 00 to 5 , try to match the prints as best as possible.
Then with your dichroic make match prints with the magenta and yellow filters

remember that magenta filter 10unit change = 1/3 stop density change
" " 30 unit change = 1 full stop
whereas the yellow filter barely changes the density when changed

This is a long and boring process but it will work if you are stuck

 

[bwoolam]

Ilford website still posts the same dial in settings for LPL dicroic heads as Seele posted. wild bill

 

[Dave Miller]

The two filter method is supposed to maintain exposure times, whilst the single filter method gives varying exposure times for which correction factors are published. The reason the two filter method only goes to grade 4 is because the exposure time cannot be maintained at the higher contrast. Ilford say it doubles at grade 5.
If you use split grade printing none of this matters much.