A solution

[Machiel]

To what ?

[Willyd6869]

too little contrast?

[carl_valiquet]

Seems you put a red filter that acts like a safelight in front of the enlarging lens.
You can turn on the enlarger's lamp and project your negative on the
black and white paper's emulsion
The paper will not be exposed.
A good solution to make sure the image is projected correctly.

[Broadside]

I think that is for printing on multigrade paper. Different colours giving different contrast levels.

[Machiel]

So, this is the story.

With both the Leitz Valoy and the Focomat 1C (the non filterdrawer version) we have to solve how to use the contrast filters. Some put them inside the lamphead on top of the condensors. Some take the redfilter from its holder and use that.

I wanted something else. Something that leaves room to work the aperture ring of the lens, and that has a large enough diameter to let the light through. Leitz actually made this under-the-lens holder, but I can't find it.

So, suggested by a friend, I used a Beseler holder that needed a little modification. After that one can fix it tight to the enlarger, it works great.

All in all it means we can use these beautiful enlargers . . . enclosed the same idea, this time showing the Focomat 1C . . .

[fotohuis]

You can also rebuild to a Heiland Split Grade system. Even possible with a cold light LED source for the V35 were no Philips HLX bulb is available anymore.
In this way you will have a most sofisticated enlarger system.