Difference between Condenser and Variable Contrast Enlarger (Beseler)

Question

In high school, we used Beseler 23C-iii's - and in my current set up, am using a Beseler 23C-ii. But, I've the opportunity to get my hands on a 23C-iii with a Variable Contrast head (please note that this is different from a Dichro head).

What are the specific differences between these two models, as it would impact my printing?

The only thing that I can really see is that the VC model internalizes the contrast adjustments - so I could retire my contrast sheets and (potentially) no longer fret over keeping dust out of the condenser head.

Additionally, does the VC model adjust contrast on a linear scale? As in, I currently have filters for 0, 1, 2, etc...does the head allow for, say, 1.5 to be set?

Answer 1

Checking the specifications, the Beseler 23C-iii-XL Variable Contrast Black & White, sports a diffusion lamphouse and its adjustable grade 0 thru grade +5. I think you will find the diffusion lamphouse desirable as opposed to a condenser design. The diffusion design suppresses dust spots greatly reducing spotting time. Plus this design is favored by portrait photographers because the output has less apparent sharpness compared a condenser enlarger. The dust suppression of the diffusion enlarger is due to the fact that light hits the negative omnidirectional. Thus dust mites cast diffused shadows. The drawback is, a diffused enlarger produces prints that are about one paper grade less contrasty.

Conversely, a condenser enlarger features two plano-convex lenses that focus the light so the beams arrive at the negative plane parallel (collumated). These straight on rays cast harsh shadows of the dust motes plus every scratch and fingerprint on the negative is boosted. The condenser design boosts contrast about one paper grade plus the resulting print has increased apparent sharpness. The downside is, get out your spotting brushes because you will see a plethora of dust spots. The increase in contrast has been well studied, look up “Callier Effect”.

I was unable to verify, but I recall that they are dichroic. A dichroic filter is glass with a thin deposit of metal. They pass and hold back based on the thin-film principal. Since they are made using passive (inert) metals, they have longevity in the environment of a hot-bright lamphouse. Dichroic’ filters are a plus.

Also, this model’s lamphouse can be retrofitted to a color head and/or a black & white condenser, if you can find the parts.

Answer 2

Yes, the VC head lets you tune the contrast very finely. I would not go as far as to call the scale linear (it could be geometric for all that I know) but it lets you deal in fractions of a grade. Some VC heads are unable to go as far to the extremes as sheet filters (but if you negative requires 00 or 5 filtration you did something mightily wrong in your metering or development).

Living in the EU I am not familiar with Beselers; I use a Meopta Meograde (made under license from Ilford) and just love it. Compared to condenser head I used before I see three advantages:

• a finely tuned dial for gradation (no more hard / soft papers or filters for me)
• another dial for density, giving me additional control over light intensity (helpful when printing on 5×7" papers, when exposure times tend to get short)
• fewer glass surfaces to keep clean (dust is my #1 darkroom enemy)

But the main thing is that a VC head makes - at least in my case - for a very smooth workflow. Highly recommended!