Not at all, re-read it..........tho its perhaps a wee bit choppy, the facts are correct.
Originally Posted by Eric Rose
Diffuser and Cold cathode have a similar look, but are both less contrasty than a condenser. A condenser produces prints with greater apparent sharpness and more visible grain. I therefore prefer diffusers for landscapes and like the sharp grain of a condenser for street stuff. was I confusing, or do you think I have this wrong?!
Good question. I guess I don't even know what a dichroic enlarger head is. So now we have a third type of diffusion enlarger?
Originally Posted by dancqu
1)Light bulb and diffuser
Is that right. As someone said above, the operative feature is 'diffusion' regardless of the actual light source. would that cause all three to have the same effect?
light bulb and diffuser is like an Elwood enlarger kinda old like mine and me
Dichroic is a color head with the filters built in and are dichroic filters hence the name
cold light like Aristo or Zone VI
essentially they will yeild the same qualities in the print
I have a D3 with a cold light and Durst with a color (dichroic head) and it seems to me that the cold light is softer than the dichroic head. I print grade 3 with the Durst and grade 4 with the D 3. Maybe its just my perception. But I aslo print grade 3 with the condenser head on the D 3. And there are 2 kinds of condenser type enlarger, point source, bare blub and semi defuse with a frosted bulb. I know that Besseler made a point source head, but I have never seen one on a Omega.
[QUOTE=Paul Howell...And there are 2 kinds of condenser type enlarger, point source, bare blub and semi defuse with a frosted bulb. I know that Besseler made a point source head, but I have never seen one on a Omega.
Two kinds of condenser. Now my head is spinning :rolleyes:
By the way, my D2 condenser head has a frosted bulb and clear condenser lenses. So that makes it a semi-diffusion?
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1. Cold light - uses a tube or tubes. Normally not very suited to VC papers as the light is very blue (therefore giving fast exposures on graded paper). Even adding filters can give erratic spaces between grades and often not the full range of grades. Some specially for VC have different tubes putting out light of different colours. The relative intensity is altered giving teh VC effect (tend to be very expensive). A cold light tube (like a mini floursecent tube) meanders across the whole neg area and is close to the neg and therefore is very diffuse.
2. Dichroic Head. These heads are normally used for colour and use halogen bulbs emitting light into a diffusion chamber (hence diffuser term used) this finally exits through a peice of diffuse material (normally opal plastic) very close to the neg and so is very diffuse. I dont know the term, but multigrade heads normally use a similar mechanism, but instead of Yellow, magenta and cyan, they use just preset grade adjusters (using Y and M mixers inside) to adjust contrast. Some later Ilford MG heads work somewhat differently I beleive, adjusting the intensity of bulbs putting out light of different colours, so I have been told.
3. Condensers. They use a light source, normally resembling a normal light bulb. This light shines through lenses which focus it on the neg. The light is very directional and contrasty. The bulb may be large and frosted (less contrasty, tho more contrasty than a diffuse source by far) or small and clear - very sharp and contrasty. A piece of diffusion material can be put above the neg in any of the condenser types (assuming this can physically be done) to soften the light and make it more diffuse.
Getting even lighting of the neg and reasonably fast exposures are the problems associated with placing diffusion material into a condenser effectively. Some enlarger are designed for this (such as some Durst heads) to broaden the flexibilty of a given head, but DIY solutions may be tougher to get right (with problems such as heat build up, will the plastic melt etc....) I'm sure some have done great DIY diffusers for condensers.
What you like is personal opinion. If I could have only one, it would be diffuse light every time, tho I prefer to have both. My landscapes improved hugely when I started using diffuse light. If you use smaller formats, getting grain free well seperated skies with a condenser can be tough, but getting the grit and punch into a street scene with a diffuser can also be tough.......
"Would that cause all three to have the same effect?" That is an involved,
complex matter. I'm not sure that they can have the exact same effect.
First consider the temperature of the light sources, cold light, warmer
halogen and most warm tungsten. Then there is the shape and position
of the light source; pointy, bulbous, tubular.
I'm sure that any of the three can produce excellent results. There is
one paramount consideration when selecting an enlarger, how well it
illuminates the negative. Dan
Mine is bulbous. I shoot 35mm, 6x4.5, 6x7 and 4x5. I have a set of condenser lenses for for the 4x5 and a smaller set which seems to work for 6x7 and down. The cold light head I am considering has an semi-opaque plate of the same diameter as the 4x5 condenser lens. Given that Omega made a set of smaller lenses for small film formats, what do you suppose will happen if I use the large cold light diffuser on small negatives? any ill effect?
Originally Posted by dancqu
Those small lenses are used to focus the light onto
smaller negatives; to intensify the light level. As long
as you've coverage you're OK. Dan
point source lights are pretty rare now days. Durst still makes one I think but it is a order item I would bet and not in stock (I'm guessing here)
Aristo makes coldlight tubes that are closer to the VC paper these days. I have an Aristo VCL 4500 that is a two tube light that is aimed right at the VC paper printer.
What the photographer needs to do is learn to develop his/her film to match the light source that said enlarger has. All of Kodaks recommended development times for their films were determined to be used for diffusion enlargers. Since condenser enlargers yeild contrastier light, one must soften the contrast of the light and therefore use less time in development of the negatives.
in answering the last cold light question it will work just fine. Just put the diffusing plex in the bottom of the cylinder and put the light on top of it. Cold lights like to be as close to the negative stage as possible. The plex is not semi- opaque it is Opal glass an is opaque.