[pure-silver] Re: Durst L1200 (condensor) & uneven illumination
- From: <C.Breukel@xxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Mon, 23 Jul 2007 12:01:46 +0200
Hi Georges,
Thanks for the feedback, I did found a message from you on APUG with
below desription..;-)..
That is why I tried your tricks with tracing paper, some plastic, and a
piece of roughed glass between the mirror and the condensor. It did not
help, and as you observed :greatly reduces the output.
Like I said: I did not notice problems in my prints, but it nags me a
bit that such a device gives this uneven output...perhaps my taking
lenses have some light fall-off at the edges, and this is compensated by
the enlarger..;-)..
Best,
Cor
> -----Original Message-----
> From: pure-silver-bounce@xxxxxxxxxxxxx [mailto:pure-silver-
> bounce@xxxxxxxxxxxxx] On Behalf Of Georges Giralt
> Sent: maandag 23 juli 2007 12:45
> To: pure-silver@xxxxxxxxxxxxx
> Subject: [pure-silver] Re: Durst L1200 (condensor) & uneven
illumination
>
> Hi Cor !
> I own a Laborator 1000 and the situation is worse tha yours because
the
> lamphouse was designed for a 100 mm dia bulb which is not made
anymore.
> I've tried, with success, a Philips double enveloppe halogen bulb of
95 mm
> dia.
> It makes things in the 3/4 of a stop range, and I've evened the
lighting
> by
> inserting a frosted glass PLUS a sheet of tracing paper in the filter
> drawer
> between the bulb and the mirror above the condenser. This puts me in
the
> 1/3 to
> 1/10 stop range, but reduce the light output very much (a pain with
the
> slow
> Forte and Foma papers and the RH Designs Analyser going only to 255
> seconds)
> Another way would be to put a sheet if translucent Perpex (sp ?) above
or
> bellow
> the condensers and see what it does. Doing so you transform your semi
> directed
> light system into a diffusion enlarger. I wonder if you will enjoy
> this....
> Selon C.Breukel@xxxxxxx:
>
> > ( I have posted this message before on APUG, which actually felt
like
> > betraying the pure-silver list...;-).., I actually like our mailing
list
> > format better, so it served me right that I got little feed-back on
> > this..;-)..), anyway.....
> >
> >
> >
> > Hi,
> >
> > I have been using a Durst L1200 Laborator with a condensor for about
15
> > years now (35 mm upto 4*5 inch). I have always been quite happy with
> > this enlarger. In the past I have checked the illumination and
noticed
> > it was a bit off.
> >
> > Recently I looked in more detail: I used the correct condensors and
lens
> > (80mm), focused a 6*6 negative , removed the negative, and used a RH
> > Zonemaster II in the density mode to check the illumination on the
base
> > board.
> >
> > I now noticed that the corners and the side were quite off. The
L1200
> > has on the side 2 knobs for the lamp postion, and the lamp housing
can
> > be moved in and out as wll.
> >
> > The best I could do is roughly the following:
> >
> > 0.15 0.08 0.16
> > 0.08 0.00 0.07
> > 0.17 0.06 0.12
> >
> > (so the middle put on zero, the other figures representing the very
> > corners and sides). Initially I mistrust the Zonmaster, I mean 0.1
means
> > 1/3 stop and 0.15 1/2 a stop.
> >
> > I find this alot, OTOH I never realy noticed this when printing
> > (probably tells that I am not that a good printer I guess..
> >
> > So I checked by exposing a grade 5 piece of paper to about middle
grey,
> > and sure enough it showed the same effect, (although I am not sure
if I
> > realy see that half a stop difference) the corners beeing somewhat
> > lighter.
> >
> > Somehow I find this dissapointing for such a sturdy enlarge of great
> > reputation, you might say why worry if you're happy with prints, but
it
> > is nagging..
> >
> > So I tried to diffuse the light between the bulb (a guinine Phillips
> > Photocresenta, 75 watt) and the condensor with some milky plastic,
> > paper, and even a piece of groundglass. It did not help, and even
made
> > matters worse.
> >
> > Another solution would be a diffusion head, a CLS501.
> > I happen to own such a head, but I was not too happy with it for
various
> > reasons.
> >
> > So any suggestions on improving matters will be greatly appreciated!
> >
> > Best,
> >
> > Cor
> >
>
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>
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