I own a Focomat V35 since about 6 months back and have been using it quite frequently since then. Mine is the new model that originally uses the Philips 13139 bulb. It so happens that it was exactly that type of bulb that was installed in my enlarger when I bought it.
But, I few weeks ago the bulb stopped working and since the Philips 13139 is no longer manufactured I ordered a Osram 64615 after reading at http://www.bonavolta.ch/hobby/en/photo/v35.htm that it should work. Once installed, it did fit but the enlarger is nowhere near as bright as it was when using the original Philips 13139.
I have done some controlled tests using the P13139 and the O64615 and when just projecting the light without a neg in the carrier the light with the Osram lamp is about 2 stops darker.
I have seen on other sites that this has been discussed before but I wonder how other people here are doing that uses this enlarger. I finally found a Philips 13139 to buy and install, sure enough the enlarger is now as bright as it was when I first bought it.
But how to proceed? I refuse to use the Osram lamp, the enlarger is pretty much useless when printing bigger prints due to the long exposuretimes. Do you guys have any suggestions to other bulbs that work as good as the original 13139 or any other tips or advice regarding replacement bulbs?