Converting to point source

[Paul Howell]

I just bought an old federal enlager 35mm to 6X9 (1939 issue) to convert to a point source. I selected the federal because it has narrow lamp housing. Any ideas concerning a small clear bulb? I have an old Durst Color head that I can canablize for it's halagon bulb. A couple of years ago I bought a Russain 35mm point source enlarger that uses a very small tungston bulb, looks like a large flash light bulb, all I had to do was get a new tranformer to step the voltage up to 220.

 

[RobC]

well if you look at the lamp for an L1200 varipoint, it uses this one:

Dead Link Removed

so if you contact a local durst dealer or someone on the list who has one, then you may be able to get the code of the bilb and buy one from a usual bulb manufacturer for a lot less than durst are charging.

I wouldn't have thought the tungsten bulb from a colour head would be a point source bulb. Way too big.

However, an opal bulb with a sheet of metal with a hole in it, might do it although it could get a bit hot so care would be needed setting it up.

 

[Larry Bullis]

I have an old Durst Color head that I can canablize for it's halagon bulb.

Most of the colorheads used halogen bulbs with those built in reflectors. All that I ever used did, and I printed color in custom labs for far too many years, probably used some 30 or so enlargers.

Those bulbs won't provide point-like light. Ideally, a small bare bulb in a blackened chamber. The smaller the better. Some of the new automotive headlight bulbs might work, if you had a 12v high current power supply.

 

[Paul Howell]

well if you look at the lamp for an L1200 varipoint, it uses this one:

Dead Link Removed

so if you contact a local durst dealer or someone on the list who has one, then you may be able to get the code of the bilb and buy one from a usual bulb manufacturer for a lot less than durst are charging.

Thanks for the link. It is a point source, do you know what kind of thread it uses?

 

[RobC]

well if you look at the lamp for an L1200 varipoint, it uses this one:

Dead Link Removed

so if you contact a local durst dealer or someone on the list who has one, then you may be able to get the code of the bilb and buy one from a usual bulb manufacturer for a lot less than durst are charging.

Thanks for the link. It is a point source, do you know what kind of thread it uses?

no sorry I don't. And remember you have to be able to centre the light filament over the condensers exactly.

You can see that bulb in this picture.

View attachment 10868

 

[Paul Howell]

no sorry I don't. And remember you have to be able to centre the light filament over the condensers exactly.

You can see that bulb in this picture.

View attachment 10868

The bulb seems to have a nonstandard base, but the shape looks like a 250 watt halogen that I have with a standard screw in base, it is not intened to be used for a color head, I forget where or why I got it. The lamp housing may have a fan on the side, and the bulb is only a 100 watts. I use a 150 watt for my Durst 601 as it is so I dont quite understand the reasoning behind the fan. .

 

[RobC]

the picture shows the variopoint L1200 head. I have the cls501 colour head and not that one. But I know that head has a voltage rheostsat in it for adjusting brightness and it also has controls for adjusting x and y position of the lamp so that it is centred. I'm not sure if it has a fan in it but what you see as a fan may well be those controls.
A 100W bulb would have less need for a fan. My CLS501 has a built in fan but it also has a 250W bulb which is required because with colour you are using two filters and also a diffusing box which stops a lot of light. With a point source you only have one filter and no mixing box and its focussing light onto the neg so it should not require as much light output.
And temp in condenser setups can be a problem with negatives over heating and popping.
If an L1200 works with only a 100W bulb I suspect you would be over doing it with any more than that on a 6x9 enlarger.

 

[RobC]

I dug my manual out and the box on the side of the variopoint head is the control unit for x and Y position of the lamp. I'm pretty sure there is no fan.
I also have a modular 70 B+W and that uses a 100W opal bulb with no fan.

 

[Paul Howell]

the picture shows the variopoint L1200 head. I have the cls501 colour head and not that one. But I know that head has a voltage rheostsat in it for adjusting brightness and it also has controls for adjusting x and y position of the lamp so that it is centred. I'm not sure if it has a fan in it but what you see as a fan may well be those controls.
A 100W bulb would have less need for a fan. My CLS501 has a built in fan but it also has a 250W bulb which is required because with colour you are using two filters and also a diffusing box which stops a lot of light. With a point source you only have one filter and no mixing box and its focussing light onto the neg so it should not require as much light output.
And temp in condenser setups can be a problem with negatives over heating and popping.
If an L1200 works with only a 100W bulb I suspect you would be over doing it with any more than that on a 6x9 enlarger.

I plan to install a rheostat as well, even my cheap Russian 35 mm has a rehostat so I tone down the wattage. The Federal has a glass negative carrier, both 35 and 6X9, if this does not work I guess I will buy the lamp for the Durst and find a socket. thanks for your help.