The Durst enlargers seem to be quite efficient with their lighting.
My M600 with a 75w PH211 was marginal, with most of my exposures about 10 sec. I prefer to be 15-25 sec, so I have time to manipulate the print if I want to.
This is for a Durst F30 which I expect will be just as fast or maybe a bit faster.
Does anyone know of a smaller wattage photo enlarger bulb than the 75watt PH211?
I would like to get down to about 40watts or so.
Whatever bulb you experiment, remember that the size (length) of the bulb must be the same as the original, or else you will have a hot center problem. To my taste, papers these days are too fast. I know what you're going through.
My remedy was a ND filter. Either that, or use a longer enlarging lens so you can run the head higher up the column. Experimenting with bulbs will most likely be fruitless.
I too use an ND filter when I'm working small. The longer lens trick doesn't actually work, because you're not dealing with a point source and square law. Projecting a same sized image on the easel will have about the same intensity whether its a 50, 80, 100, etc. lens.
Sounds like you could use a Variac. An adjuster transformer. This will allow you adjust the voltage and dim the light as needed. They were not uncommon, Beseler had one that mounted on the 45 series enlargers but standalone units are common. A bit pricey new but there should be lots of used ones out there.
A standard light dimmer might also work for a 75w bulb - I can't say for sure though.
Dimming the bulb turns it too yellow. Then you'll be fighting contrast and exposure standardization. You'll just have a mess. On top of that when you dim a bulb by voltage, the glow gets smaller, possibly causing evenness problems from center to edge. Regarding my longer lens idea, I reserve the right to say something dumb once in a while.