Pink filter on Durst 605

Jesper · Jul 24, 2016

I tested a Durst 605 enlarger with colour head today and was a bit surprised at seeing the unfiltered light with a distinct pink colour. When I looked inside the lamp housing there is a clear glass filter just in front of the lamp and after that is a pink glass filter before the light continues to the three colour filters.
Does anybody know why?
I will only use the enlarger for B/W, will I need it?

grahamp · Jul 24, 2016

The clear glass is likely a heat filter. The pinkish one could be to suppress UV wavelengths. This is a tungsten-halogen bulb?

Jesper · Jul 24, 2016

The bulb is an Osram Decostar 51s 44870 WFL and the data sheet says nothing about tungsten-halogen but it has a built in UV-filter.

mudfly9 · Jul 24, 2016

There should be a knob on the back of the head that slides the pink filter in and out when you twist it.

Jesper · Jul 24, 2016

mudfly9 said:
There should be a knob on the back of the head that slides the pink filter in and out when you twist it.

and that solves the mystery. Thank you for your time helping me solve the problem of the pink filter.

Doremus Scudder · Jul 25, 2016

The mystery still remains: what purpose does the pink filter serve and why is it designed to move in and out of the light path? Enquiring minds want to know.

pentaxuser · Jul 25, 2016

Doremus Scudder said:
The mystery still remains: what purpose does the pink filter serve and why is it designed to move in and out of the light path? Enquiring minds want to know.

My thoughts entirely. I have the Durst M605 and this must be a quite different head as I have no rear knob that dials in pink. There is a white light lever on the side that withdraws all three dichroic filters and a front knob that adds an equal amount of extra magenta and yellow which might appear to add pink. I have never used this by itself but if the three colour dials are all set at zero thus giving white then it may be that turning this knob in will add the extra magenta and yellow(pink?) thus appearing to be a knob that adds pink.

pentaxuser

shoot6x7 · Jul 25, 2016

I believe this additional filter extends the filtering range when you're already using some dialed in already.

Dali · Jul 25, 2016

It is used to add 30 points of yellow and magenta is case the 130 points permitted by the front setting is not enough. I never used it but it is how it is described in the user's manual.

AgX · Aug 14, 2016

Jesper said:
The bulb is an Osram Decostar 51s 44870 WFL and the data sheet says nothing about tungsten-halogen but it has a built in UV-filter.

All lamps of this kind are tungsten-halogen.
Except for a few energy saving models they all transmit more than half of their overall heat radiation back through the reflector which is designed as a filter.

The UV filter is a rather new feature to spare goods and people during long time use.

Basically such lamps would work in a diffusor enlarger. Except that those household lamps are not overrated and thus deliver a more reddish spectrum than enlarger types.

AgX · Aug 14, 2016

grahamp said:
The clear glass is likely a heat filter. The pinkish one could be to suppress UV wavelengths.

The Durst M 605 indeed got two filters in front of the lamp:
-) heat filter
-) UV filter

Pink filter on Durst 605

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