Diffusion vs. Condenser vs. Format vs. Paper

[Corran]

Very nice, Corran. Don't you just love Galerie?

Yes I'm starting to really like Galerie! The highlights print a little nicer than Warmtone it seems like to me.

Luis, yes 'most' of my negatives print on G2-3, maybe 4 sometimes. But I do make mistakes and last year I can think of 2 negatives that were severely underdeveloped due to an issue with developer. So those are problematic. Other than that, the occasional image on a roll of 120 that was radically lower contrast than the rest of the roll and therefore can't get N+whatever developed sometimes gives me trouble. I try to shoot a whole roll at one contrast range but that doesn't always work out.

The underdeveloped negatives scan just fine and can be adjusted, so soon I am going to be trying film "burning" from a digital file to make a negative and print from that those few "oops" photos that are still photographically good but are problematic in printing.

[Drew Wiley]

So Nodda, how on earth does an integrating sphere remark apply to the basic problem of even diffusion over a neg carrier in an enlarger? Different applications. Yeah, I have such devices for measuring illumination consistency on the paper plane or whatever, but this is about getting it consistent to begin with.

[Nodda Duma]

Because, Drew, the mixing box on diffusion enlargers are a close approximation to integrating spheres and behave within the same principles. While most photographers know the parts that make up a diffusion head enlarger, I am not so sure most know why and how it works and what's important.

When you are trying to minimize variance in illumination, it pays to understand the characteristics of the mixing box which are important. Namely: the ratio of the mixing box volume to the size of the output port, and the internal surface type and design (PTFE powder coat is better than sheets of styrofoam, and no structure should be visible from the position of the lens when looking in).

Once you understand the aspects of a diffusion enlarger hat's important, you can make an informed evaluation/comparison of enlarger heads (or put that knowledge into making your own) and select an enlarger that gives better illumination uniformity than others.

[John Layton]

Semi-hijack...thinking about a machinist/photographer at a company called Lightsphere (Sutton,NH) - who made some parts for me back in the day, and who at one point invited me to gaze into the most technically perfect white sphere (developed for space satellites, etc.)...into the most perfectly diffused white light - the absolute purity of which I could never have previously imagined...would make an amazing head for something like an 11x14 Durst!

[Tin Can]

Semi-hijack...thinking about a machinist/photographer at a company called Lightsphere (Sutton,NH) - who made some parts for me back in the day, and who at one point invited me to gaze into the most technically perfect white sphere (developed for space satellites, etc.)...into the most perfectly diffused white light - the absolute purity of which I could never have previously imagined...would make an amazing head for something like an 11x14 Durst!

How big do you propose?

I imagine at least 36" diameter or double that.

The openings are the flaws.

Maybe an array of below the center of LED aiming up to refect down the hole.

I like it!

[Tin Can]

The dome is affordable. http://www.eztopsworldwide.com/domes.htm

[John Layton]

Correction...the company is called Labsphere: https://www.labsphere.com

[Nodda Duma]

Yep, Labsphere is well-known in my industry. The other company I know of that makes integrating spheres is Electro-Optic Industries out of California. There are others, but those two are the main ones in the US.

[Greg]

A lot depends on the process and your final prints and subject matter.

When I was enlarging EM (Electron Microscope glass) plates used a point light source, sharpness prioritized over tonalities. Huge Durst enlarger

For 35mm film enlargements a condenser light source and a color head. Was a Leitz Focomat V 35 40mm lens was superb

For 120 and 4x5 film a diffusion head. Have used a Zone V enlarger with a diffused light source and currently a Durst CE1000 color enlarger with its diffusion light source and couldn't tell the difference even when I used the Durst with split filtration.

Ideal enlarger... I firmly vote for Durst with it's excellent negative, lens, and paper alignment. For lenses I have mostly used older all metal El Nikkors. The 63mm f/2.8 EL-NIKKOR the best optic I have ever (and still do) used for 35mm.

[Drew Wiley]

Well, Nodda, wish I had you in my corner back when I was hotrodding my own colorheads, but all but one have illumination eveness better than 1/10th stop. The other enlarger is within a third, but due for a tweak. I've been pretty involved over the years with progressive improvements on industrial spectrophotometer designs - more in terms of solicited feedback from engineers who knew me - but I prefer old-school barium sulfate spectrophotometer paint over any other kind of diffusion box white. With one of my Durst colorheads, the standard 12X12 polished stainless mirror box is perfectly even to begin with, provided I don't use wide angle lenses. Certain repetitive color processes like dye transfer are best done without any manual dodging or burning. I did get help with custom electronics from ZBE. Two of the enlargers are true simultaneous additive.