Bright circle from enlarger lens

[Patrick M]

I have just acquired a Fuji 450 M-D enlarger with a Beseler dichro head and a 135mm Nikon lens. This is my first large format enlarger so bear with me please.
With a 4x5 neg in place the image on the easel is mainly a bright circle in the middle of a faint rectangle.
I can focus the image but at any aperture and with the head at any height and the focussing bellows at any extension, the bright circle remains.
Does anyone have any idea what could be causing this and how I might change it.
There is nothing between the Beseler diffusion screen and the lens.

[Andre Noble]

does it have a 35mm mixing box installed?

[Patrick M]

No, nothing between Beseler head and enlarger lens.

[Gary Beasley]

The mixing box is inside the head. Did the gear come with any manuals?

[ic-racer]

I have just acquired a Fuji 450 M-D enlarger with a Beseler dichro head and a 135mm Nikon lens. This is my first large format enlarger so bear with me please.
With a 4x5 neg in place the image on the easel is mainly a bright circle in the middle of a faint rectangle.
I can focus the image but at any aperture and with the head at any height and the focussing bellows at any extension, the bright circle remains.
Does anyone have any idea what could be causing this and how I might change it.
There is nothing between the Beseler diffusion screen and the lens.

"Beseler dichro head" can mean many things. Need a picture of the configuration.
"...nothing between the Beseler diffusion screen and the lens." Where and how are you positioning the negative? Is the negative holder Beseler or Fuji? Is a mixing box present or absent? If present is it Fuji or Beseler and what are the dimensions? Is it installed upside down?

[Patrick M]

It is a Beseler 45S head.
The negative is in the Fuji holder.
The mixing box is integral to the Beseler head and is labelled '4x5 diffusion chamber'; it is installed as per images in the Beseler handbook.
I believe this set up - just as I have it - has been used previously to print 4x5 negatives.

[Andre Noble]

I believe some guys on this forum could solve this in seconds if you posted 3 or 4 different cell phone snaps of your enlarger as it is set up, including the illumination pattern on the underside of the mixing box, with enlarger light turned on and also the illumination pattern at the baseboard that you speak of. Lets not make this a riddle.

[Patrick M]

Here are some images.
I hope these help.135540135541135542135543

[Patrick M]

Here are some images.
I hope these help.135540135541135542135543

[Patrick M]

I have just been on to the previous owner and the problem is solved. The condensers were removed for shipping and I had not reinstalled them because I was not familiar with the inside of enlargers. I am now familiar with the inside of this one!
Many thanks for all help.

[ic-racer]

Now you have my curiosity, if you have the 4x5 mixing chamber in the Beseler head, where are the condensers going?

[Andre Noble]

I bet it is a relief you figured things out. Yeah, my gut reaction was to say the condensers. But then since its a diffusion enlarger, I did not think it had condensers so I didn't say anything.

Looks like a great enlarger though.

Getting into traditional darkroom photography will help develop your problem solving skills and give you confidence.

[Luis-F-S]

Now you have my curiosity, if you have the 4x5 mixing chamber in the Beseler head, where are the condensers going?

Not familiar with that head. Is it possible it has condensers instead of a mixing chamber? L

[ic-racer]

Not familiar with that head. Is it possible it has condensers instead of a mixing chamber? L

No picture in the manual but it indicates that instead (or addition??) to the mixing chambers, a condenser is available. My curiosity lies in rare "Dichroic Condenser" enlargers, as I have one, and wondered how Beseler manages the inherent issues with dichroic filters and focused light.

[Bob Salomon]

No picture in the manual but it indicates that instead (or addition??) to the mixing chambers, a condenser is available. My curiosity lies in rare "Dichroic Condenser" enlargers, as I have one, and wondered how Beseler manages the inherent issues with dichroic filters and focused light.

Dichroic condenser enlargers are not really all that rare. Kaiser still makes them in color head, VC and straight condenser head versions.

[LabRat]

I think dichroic condenser enlarger heads are GREAT!!!! I loved printing Type C and R on them professionally... They had a greater "snap" and saturation for color, and made easy printing for "microcontrast" on B/W routine... They seem to be a bridge between a condenser and a diffusion head (confusion???) with the best of both worlds...

For an improvement over a condenser head, I think it might have to do with the bulb itself... Let's say with an enlarger with an old Edison based PH212/150W bulb, the bulb is thought to be an even diffuse source over a condenser... But if you look at that surface, you can see a little uneven "hot spot" that can vary bulb to bulb due to manufacture... (And the bulb is spherical???) The condenser is focused to this area, but this will lead to the condenser "seeing" this area and projecting this unevenness...

Now if one replaces that bulb with a mixing box/diffuser (at the same height as bulb), the condenser focus (at the former bulb height) will be less critical as the condenser "sees" a more even, larger source, so problems of "fringing" and other off-axis effects are minimized... And it seems to introduce a little diffusion into the system... (So the image seems to have a stronger "bone structure" due to the condensers, and a pretty tonal/color scale that seems to "weave" through that "bone structure" due to the diffusion...

But I have been using these heads mostly for smaller format Leitz enlargers that I have restored/upgraded (1a/1c/ValoyII/2c)... I plan on adding a dichroic condenser system to my (modified) Beseler 45 to see what happens, and if it will make such a big difference as the small format enlargers did...


Steve K

[ic-racer]

Dichroic condenser enlargers are not really all that rare. Kaiser still makes them in color head, VC and straight condenser head versions.

Thanks for mentioning that. I checked out the Kaiser and see it is very similar to the Philips PCS that I have. In fact it looks like some parts may be interchangeable. I see the technique is similar to the Philips in that the dichoric head projects to a translucent disk and the disk is projected by the condensers.

[StoneNYC]

This is fascinating to me, one of the reasons I prefer a condenser head is the sharpness and micro contrast that seems, as another said "snappier" and I've read that this is often the perspective but the ease of cold head / diffused heads seem to outweigh the benefits of the condenser, so I'm very curious to know more about these, are they made in 10x10 size for 8x10 enlargers? Anyone have a picture? I'll research more but if anyone has more info to direct me that would be great (and OP I hope you don't mind me budding in since you seem to have solved your initial problem).

[Bob Salomon]

Thanks for mentioning that. I checked out the Kaiser and see it is very similar to the Philips PCS that I have. In fact it looks like some parts may be interchangeable. I see the technique is similar to the Philips in that the dichoric head projects to a translucent disk and the disk is projected by the condensers.

Other then the fact that they both look like enlargers there is no other similarity between them. One is an additive type color head and the other is subtractive.

[ic-racer]

Other then the fact that they both look like enlargers there is no other similarity between them. .

Bob, do you know if the lenspanels, negative carrier, and filter holder are incompatible between the Kaiser and Philips, as I am seeking those things for my Philips? Thanks in advance.

[Bob Salomon]

Bob, do you know if the lenspanels, negative carrier, and filter holder are incompatible between the Kaiser and Philips, as I am seeking those things for my Philips? Thanks in advance.

Completely different. The Kaiser is a 69 enlarger, I believe yours was a 67 model.

[ic-racer]

Thank you Bob.

[Patrick M]

Now you have my curiosity, if you have the 4x5 mixing chamber in the Beseler head, where are the condensers going?

Sorry for the delay in replying; I've been away.
The condensers are in the Fuji part of the enlarger head, below the Beseler diffusion screen and above the negative holder.
I would like to use this enlarger in diffusion mode only but can't see any way of doing that. If anyone has any ideas about this I'd be glad to hear them.

[ic-racer]

The diffusion plate of the 4x5 mixing chamber of the Beseler head needs to be very close to the negative carrier. Perhaps a centimeter.

[Patrick M]

Understood. Unfortunately not possible in this set up. The mixing chamber of the Beseler head is about 20cm above the neg. Perhaps I could put in another diffusing plate just above the neg after removing the condensers.

[ic-racer]

Lets backtrack. So you eliminated the original problem by using the Fuji condensers. Yes? But you really want a diffusion enlarger. The Beseler head won't fit close enough to your negative holder. You can turn your condenser into a diffusion source by putting a piece of diffusion material between the condenser and the negative. One of these inexpensive Rosco filters might do the trick:
https://www.rosco.com/technotes/filters/RoscoDiffusionKitData.pdf

[Patrick M]

Many thanks ic-racer. You've been a great help. I'll look into getting one of the Rosco filter kits and let you know what happens next. Meantime I'll print using the condensers and use processing to reduce contrast and harshness (as I see it) from condenser printing.
Thanks again.

[ic-racer]

I have tested my 'Dichroic Condenser' heads vs 'Dichroic Diffusion' heads and can't tell which is which when making the 'best print' on each head.
http://img.photobucket.com/albums/v670/ic-racer/condenser%202.jpeg

[Patrick M]

Those images certainly look very similar. Perhaps it is me being too harsh. I'll do some more testing today and let you know.

[ic-racer]

The large diffusion screen seen by the condenser in my case ( and yours) will make the enlarger behave more like a diffusion enlarger, compared to a point source enlarger.