Point Light Source for the Focomat Ic

[chip j]

Hilo, I have NOT been able to find any info on this enlarger, but it gives a soft, antique, kinda 1920s look to the print, even w/a Focotar 2.

 

[Marco Buonocore]

What a great find - it looks beautifully designed. I have used a point light on my Durst enlarger quite a bit over the past few years. The best tips I can give you for starting out are:

- Use AR glass in your negative carrier, not anti-newton glass. The pattern of the AN glass will show up on the print.
- Mask off *any* stray light around the negative. If you're printing full frame negs, your negative mask has to be really accurate. This prevents hot spots, and having the filament of the lamp visible on prints.
- Learn to focus the lamp, and center the lamp filament on the easel. This is not a step done in "normal" enlarging, and is easy to overlook. The lamp is focused by moving its position up and down, and is related to the negative size and lens used. This maximizes sharpness.
- If possible, use a longer lens. This prevents vignetting. I'm not sure if you'll have this option on a 1C, as the condensers are probably designed for a 50mm lens.
​

Good luck!

 

[Hilo]

Thank you Marco, which Durst enlarger do you use?

 

[Marco Buonocore]

I use a 138 - it has a tremendous system for focusing the bulb. You can move up, down, backwards, forwards and side to side. It makes the process very simple.

I also happen to have coated condensers (the "T" versions), which are supposed to reduce the flare when using a point light source. I've never compared these to uncoated condensers, but I figured Durst must have had a reason. Certainly, the anti reflection glass in the negative carrier makes a significant difference. I got the AR glass from Mike at Focal Point, and it was a revelation.

If the Leitz system uses a variac to control the bulb output, pay attention to the colour of the light. Mine gets quite warm when set to a low output - this in turn effects how variable contrast paper behaves. There is certainly a sweet spot, where the bulb has the same color temperature as a regular tungsten enlarger bulb. The PLS works wonderfully with graded paper, and you can really notice the increase in contrast compared to a more diffuse light source.

 

[Hilo]

Thanks again Marco, you raise good questions. I had not yet thought about how this point light source will deal with multigrade paper. Wish the good old days of Record Rapid were here again . . . Anyway, it will take more testing than usual, which is okay.

Not sure if I understand the bit about "focusing the lamp". You mean moving up and down the PLS changes the sharpness of the film's grain?

The Focomat 1c has an optional AN glass that you slide over the condenser's lower glass. That presses flat the negative. It is easy to replace this AN glass by a mask cut from black pvc sheet, preventing the film to touch the normal glass of the condenser . . . Not easy to make (for instance) a 60mm lens work on a 1c. However, I can also try out the PLS on a Valoy II which takes any lens.

I also have a Durst L1000 mounted to the wall and that one has a good bulb system for adjustment . . . not sure if Durst did a point light source for this enlarger though.

 

[Paul Howell]

Point source print very hard, you will not want to print higher than grade 2. As a matter of fact Durst did made a point source head for their enlargers. I've been told that Omega did as well but have found any information, KHB site does not list one. I lower the halogen lamp I use in my DYI point source so that the filament don't show and the light is at the right height for max sharpness. You will see the image sharpen as you raise and lower the lamp. What I do is focus with the focus control, then focus by adjusting the lamp.

 

[~andi]

Hi Chip,

I have the small condenser & diffusing disc--they came installed on an ANCIENT Valoy I bought! That Valoy won't work well w/o BOTH condensers.

Hilo and I figured it out, thanks to your post we found the info about that little condenser in an old Leitz publication. I summarized the findings here:

https://www.photrio.com/forum/threa...t-looks-like-a-condenser.123531/#post-2078996

Thank you very much for the pointer!

Cheers
Andi

 

[chip j]

THANKS so much. Yes, my ancient Valoy came w/the ventilation ring.

 

[Hilo]

Here a picture of the cover of said catalogue, it is from April 1940. If anyone has the US version of this I would appreciate some scans.

 

[Marco Buonocore]

Not sure if I understand the bit about "focusing the lamp". You mean moving up and down the PLS changes the sharpness of the film's grain?
.

Focusing the lamp isn't all that hard - it is directly related to the condenser and lens being used. Because the Ic is designed strictly for 35mm, this won't be too difficult. My procedure is, I will roughly compose and focus the negative to the size I am printing. Then, I will remove the negative from the carrier, and focus the lamp. Be careful not to change the focus, or enlarger height.

The lamp is focused by moving it up and down, or back and forth depending on the configuration of the enlarger head. On the Ic my guess is, it will be moved up and down. Look for the projection of the lamp filament on your easel. You want the filament to be as sharp as you can make it, and as centered as possible. I should note, you want to position the lamp in the socket so that the filament is facing the lens. It takes a little practice to see the filament, but once you're aware of it. it pops out.

Once the filament is as sharp as you can make it on the easel, and centered, then you have "focused the lamp". In practice, it takes about as long to do as focusing a negative - it's just that it's a new step, which is why it may seem confusing. With the lamp focused, you illumination will be as even as is possible, and my feeling is, the grain will be as sharp as possible. Earlier on in the thread I mentioned it was critical to mask off the negative very tightly - no stray light. If this is done, you won't see the filament in your prints.

With the lamp focused, put your negative back in the carrier and start printing. If you're printing a bunch of negatives from the same format, and to the same enlargement factor, you won't have to re-focus the lamp.

 

[Hilo]

Marco, thanks !

Okay, your explanation is easy to understand and it makes sense. When I printed with the Leitz point light source in 1978, I had no clue about printing. It just went well, but now I realize that was being lucky. Since then I have only used 150 - 250 watt opal bulbs with the Leitz enlargers.

One thing, the negative holder of the Focomat Ic masks off the the single 135mm negative but it allows for a narrow black border. Moreover, I use filed out Ic masks which then give a little more black border. Those borders I mask off with the easel. Including the black borders means light is directly coming through at all four sides, you think this will have the same effect as your stray light? Of course I will just try . . .

Sofar, when turning on this lamp, I notice very uneven projection with the lens closed. With the lens open it becomes much better and when I lower the bulb the illumination becomes very even and for sure even enough to print. However, this is without a negative.

I must look again at the placement of the small bulb. I had to install a new one and, figured from front to back, it sits perfectly in the middle and there's only one way to place it. But figured from left to right I have some millimetres to play because of the length of the two pins . . .

 

[John51]

This guy is making his own point source enlarger.

I've watched it a couple of times and am still a bit confused on the 'big print from small neg' or 'small print from large neg'.

 

[Marco Buonocore]

One thing, the negative holder of the Focomat Ic masks off the the single 135mm negative but it allows for a narrow black border. Moreover, I use filed out Ic masks which then give a little more black border. Those borders I mask off with the easel. Including the black borders means light is directly coming through at all four sides, you think this will have the same effect as your stray light? Of course I will just try . . .

Sofar, when turning on this lamp, I notice very uneven projection with the lens closed. With the lens open it becomes much better and when I lower the bulb the illumination becomes very even and for sure even enough to print. However, this is without a negative.

Hi Hilo,

With regards to the negative carrier mask - all I can say is that with the point light source, you want the mask to be as tight as possible. I print mostly 6x6 with mine, and I cut a mask to cover the rebate. It cuts down on the dense spot you will get in the middle of a print, presumably the filament. I'm pretty fussy, and this seems to solve what would otherwise be a deal-breaking problem. Test and see with your setup, I suppose. Pick a negative with a lot of highlights or even tones in the middle of a print.

Also, with a point light source, the lens can only be used wide open - no exceptions. You will get the shadow of the aperture blades in your print if you stop down the lens. It is one of the times I really value my Apo-Rodagon lens, as it functions very well wide open.

My experience is, with the bulb properly focused, the negative masked off, and a good lens wide open, I can get very even illumination. I use Darkroom Automation's enlarging light meter to judge light falloff around the edges of print. I can get it to 1/5th or 1/3rd of a stop in the corners, which is fine by me. I bet the Leitz set up will do a great job in this regards, as all the darkroom equipment I've used by them is beautifully designed and thought out.

 

[wfw]

I'm glad to say that today I located my own Leitz Point Source head. I've had it for years, but it's been packed away. Today it saw daylight again. After this discussion and further discussion with the OP, I am excited to actually put it to use.

But I am a bit concerned as I have only the one bulb which is installed in the unit and have no idea how much life is remaining...
What is a suitable replacement bulb for this unit?

I would think that there would be somewhere a super-bright LED which would work well, both in terms of longevity and small angular size. But it would require its own power supply and dimming circuit. That's a challenge I could probably eventually achieve, but there are others more qualified than myself.

Meanwhile, I would like to find a spare bulb to keep for that eventuality.

 

[Marco Buonocore]

There are some online light bulb sellers that seem to stock just about anything. Knowing Leitz, you'll need an adapter of sorts - they exist too. I bought bulbs for my set up (20V 100W) for pretty cheap. In the past, people would use an automobile tail light bulb and a transformer.

In theory, an LED bulb would work - it is a point light source. My only concern would be that there would be no filament to focus, as discussed earlier in the thread. It's worth trying, but if there are tungsten bulbs available , maybe there's no need to reinvent the wheel.

I'm amazed to hear about all these point light source units for the Ic coming out of the woodwork - I would *love* a dedicated PLS 35mm enlarger!

 

[wfw]

In theory, an LED bulb would work - it is a point light source. My only concern would be that there would be no filament to focus, as discussed earlier in the thread. It's worth trying, but if there are tungsten bulbs available , maybe there's no need to reinvent the wheel.

Now I'm a bit confused. Do you mean that one should focus the filament critically before inserting the negative? It seems to me that this system would function just as any other enlarger in that you'd focus on the grain in the negative for a critical focus. Am I missing something?

This is a very interesting thread as I've had the point source head packed away for the last 20 years waiting for the opportunity to use it.

 

[Hilo]

Now I'm a bit confused. Do you mean that one should focus the filament critically before inserting the negative? It seems to me that this system would function just as any other enlarger in that you'd focus on the grain in the negative for a critical focus. Am I missing something?

Will, you better read back from post 27 . . . I wondered about the same and asked Marco . . . his answer is easy to understand . . .

 

[wfw]

OK, so "focus the filament" refers to optimizing the system for evenness of illumination? That's my take-away.

 

[AgX]

The lamp is focused by moving it up and down, or back and forth depending on the configuration of the enlarger head. On the Ic my guess is, it will be moved up and down. Look for the projection of the lamp filament on your easel. You want the filament to be as sharp as you can make it, and as centered as possible. I should note, you want to position the lamp in the socket so that the filament is facing the lens. It takes a little practice to see the filament, but once you're aware of it. it pops out.

With a point-light source the negative is to be in focus on the easel, not the light source.

The image of the light source should be in focus within the lens.

 

[tomaso5906]

[QUOTE = "chip j, post: 2077843, member: 60435"] Se uso la lampadina di tipo originale del mio Durst M35 Micromat, ho una luce puntiforme modificata - ottima tonalità con sottili gradazioni di tono, "muscoloso "quadro, molto più" naturale "del solito ingrandimento della lampadina. E posso usare TUTTI gli f-stop. Il mio Durst è stato progettato nel 1946 attorno alle lampadine dei proiettori per diapositive dell'epoca. [/ QUOTE]
Ciao Chip. Ho anche io un Durst M35 Micromat. Desidero informazioni sul tuo metodo per usare la luce puntiforme, magari con foto illustrative. Ti sarei poi grato se mi inviassi il manuale di istruzioni dell''M35. Grazie.

 

[kobaltus]

Thanks Chip,

Is it possible to take a picture of the condensers in your Valoy? I don't know this older Valoy, but I imagine the condenser is (almost) the same as the one of the Focomat 1c.

If this is not easy, forget it . . .

Michael

Condersers from 1c focomat and valoy are identical, Just their the metal frames are different. And the last versions of valoy 2 condersers are antinewton treated.
The identical condenser also has meopta axomat 1a from sixties. Also great enlarger.