[pure-silver] Re: Calibrating a dichroic head
- From: <C.Breukel@xxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Mon, 26 Mar 2007 20:57:47 +0200
Hi Georges,
Thanks for your reply: it's mainly out of curiousity that I switched, I was
quite happy with the condensor head. Not having to change filters in a filter
drawer is tempting. There is always a lot of debate about diffusion heads
versus condensor heads, although Richard Knoppow points out that even condensor
heads are also partly diffusing type. You'll find strong opinions pro and con
the various heads. As well as people who claim that there is no difference in
the final prints (provided that you tune your negatives to either type). I want
to give the head a fair change, not sure if I want to change my negative
processing routine though. Putting back the condensor head is only at most 10
minutes work..;-)..And I paid 75 euros for the CLS 501, so that does not heart
too much...;-)..
My initial tests do show that pretty high contrasts are possible, not sure if
it is upto grade 5 though. I will compair the table Rob C kindly provided to my
results, but first I have to fill in my tax report before the first of april,
no more "playing" before that..
It's a good learning experience though..
Best,
Cor
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx on behalf of Georges Giralt
Sent: Mon 26/03/2007 19:30
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: Calibrating a dichroic head
Hi Cor !
I own a Laborator 1000 and a CLS450 (ancestor of the 501) so consider my
comments accordingly.
When I get the color head I thought it was wise to use it all the time,
given the better evenness (sp ?) of lighting.
So I read the Paul Butzi's article (which was kind enough to sen his
Excel calibration file) and Ralph Lambrecht's own ideas about it. I also
discussed to a local optics's PHd and started calibrate the head.
I was disappointed because I could not get high contrast prints, so i
started over develop the negs in order to get the proper contrast for
the diffusion lighting the head gave. No luck. My negs became totally un
printable using a condenser head, but still lack contrast using the
color head at max magenta.
So I put the head in it's drawer, and set back to the condenser head.
This way, no calculation, no dial error, jut put the correct filter into
the drawer and print...
I even switched to under the lens filters in order to _see_ the filter
number I print with when actually printing ! Now, I get as hard a grade
as I can using matched paper/filters and I feel happy.
Maybe the multi contrast head are a different story, but for me, a color
head is not a good thing for B&W....
Of course, this is just my 2¢ and YMMV ....
Have a nice day
C.Breukel@xxxxxxx a écrit :
> Hi,
>
> I have been printing with a condensor head on a Durst L1200 for about 15
> years. I always was a bit curious about printing with a dichroic head
> (for B&W). Last week I could lay my hands on a cheap CLS 501 colour
> head.
>
> Since I understood that when you change filter values the speed changes
> I started out calibrating the head according to an article from Paul
> Butzi (used to be on this list, or perhaps still is: anyway:
> http://www.butzi.net/articles/vcce.htm ).
>
> Basically the idea is that you match the speeds of the the different
> filter settings by trying to match the first non white step of a
> Stouffer step wedge by adding Neutral Density (ND) to the faster filter
> settings. These ND values are obtained by mixing in M to Y or Y to M
> settings (or by the ND dial on my CLS 501 head).
>
> First some remarks on the CLS 501 head.
>
> -I'll have to get used to the noice of the fan, it's not very loud, but
> its there.
>
> - I feel a very minor vibration from the fan on the head, but with my
> Peak grain focuser looking at the projected image I do not see movement.
>
> - The printing times seem roughly 1-2 stops slower than the condensor
> head.
> (this is with 35mm with a 6*6 mixing chamber, did not get the 35mm
> mixing chamber)
>
>
> - The dials on the head are very dimly lid, espec. The ND dial (yes I
> opened the little flap beneath the dials, as well as switch all filters
> away with the lever on the left, but still it is weak)
>
> The calbration process.
>
> I used a a 21 steps Stouffer step wedge, with half stop intervals (0.15
> density), Paul advises a 31 step Step wedge (1/3 stop, 0.10 density). I
> think that's indeed better, with 21 steps the judgement of the different
> steps (ie what is the first non white step) is quite hard, you'll loose
> precision (Anybody wants to get rid of their 31 steps Stouffer
> stepwedge..;-)..?).
>
> The results were a bit dfferent from his as well as in Ralph Lambrechts
> book: The amount of ND added in the Yellow range was rather constant,
> the Magenta range was the slowest of the series, especially the highest
> setting (130 M) compaired to no filter at all 130 M was 4.5 steps slower
> (2.25 stops) 130M was also 3.5 steps slower than 130Y.
>
> At the different filter settings I now know the exposure range of the
> stepwedge, which multiplied by 0.15 will give me the density range.
>
> Can I translate this density range in a grade number of in this case
> Ilford MG IV RC?
>
> I now that paper grading is rather arbitrairly, but it at least gives me
> a few starting points, until say 70Y makes more sense to me.
>
>
> If you have some feedback, tips , answers on above: I appreciate it!
>
> Thnks,
>
> Best,
>
> Cor
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