i replaced the opalbulb with a led spot (app. 15 watt).
i dont know the lumen i dopnt know the ligtcolour but it works very well.
my spot had no diffusor so i used a milkwhite plexi-glass.
no brightness falloff to the borders.
with 4x5 i have enough light (10 sec for 13x18 cm)
but for 24x36 mm i have to expose the baper for 13x18 cm about 30 seconds.
Hi Thomas - thanks for your contribution. 30 secs is still pretty good in my experience. With Ilford warmtone paper I was previously in the 60-90 seconds range for 120 and 4x5 film on 11x14 inch paper. This has come down to around 30-45 at similar apertures (f11-f16) after my conversion. It's good to see a positive influence from changing technology on our world. I'm now thinking about building an 8x10 enlarger using LED lights.