[Alt-photo] Re: 365 nm. UV-Densitometer .

[Don Sweet]

Dear Erich

Your English is completely clear and your report is very helpful. I am
looking forward to part 2.

Thanks

Don Sweet
----- Original Message ----- 
From: "Erich Camerling" <e.camerling at tiscali.nl>
To: "Alt Photo" <alt-photo-process-list at lists.altphotolist.org>
Sent: Thursday, October 17, 2013 1:09 AM
Subject: [Alt-photo] 365 nm. UV-Densitometer .


Dear members,

In 1981 I developed and built my first visible-light densitometer (
calibrated with Kodak Wratten no.96 neutral density filters) that
functioned very well in combination with silver negatives.

But in 2007 I had to go across printed colour negatives . And that gave
me a lot of problems / troubles !

So I studied the article from Mike Ware :" An investigation of Platinum
and Palladium Printing " ( The Journal of Photographic Science. Vol 34.
1986 .page 13 - 25) and red that the maximum sensitivity in alt-photo
processes ( like kallitype , argyrotype , VDB and platinotype ) is
~ 315 - 365 nm UV-light .Because I use Philips Cleo Bodycare fluorescent
lamps ( 315 - 380 nm , peak 350 nm ) in a light box and found data
about  Epson R 2400 inks = Ultrachrome K3 (
www.albertonovo.it/scan/epson_inks.html ) with a maximum A ( optical
density  ( O.D.) ) for black , blue , cyan and green ink in the range
between 330 nm and 360 nm. ( O.D. = ~ 3 ) I  started a search for a not
too expensive densitometer in that range. ( X-rite 361T is measuring at
380 nm for UV ( O.D. for inks = ~ 1.5 - 2.5 ) warm-up time 5 minutes )
and too expensive for me.($ 2850,=) But I couldn't find such a
densitometer and then I decided to develop my own UV-densitometer.
Waiting for a 340 nm. LED didn't give a serious result , so I bought a
Nichia UV-LED  : NCSU033B .  365 nm. ~ 325 mW @ 500 mA. Price ( In the
Netherlands ) ~ EUR 80.=   as a UV light source.
For the sensor I bought an EPD-365-0-2.5 GaP-UV-photodiode  ( max.
sensitivity  360 - 370 nm ) Price  EUR 75.= .

Then I started developing the electrical circuit. But unfortunately that
was much more complicated then building a visible-light densitometer.!!
After a lot of attempts who all became a failure I became a little bit
desperate.But a good friend of mine  would help me.And he did it on an
incredible intelligent way.

So now I have a perfect working prototype 365 nm. UV-densitometer with a
professional  quality  (  range D = 0,1 - 3.5 with delta D = ± 0.02 . No
warm-up time )  for an amateur price: ~EUR 500.= when you-do-it
-yourself !!!!!

To be continued next week.

PS. Because I had lessons in English more than 40 years ago there is a
serious possibility that I will make grammatical mistakes.
         Please correct me (on my personal e-mail address ) and I will
improve/rectify/correct  the text on internet.


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