Getting contrast out of Diffuser: transition from Condenser

[gbenaim]

Hi all,

Finally got the De Vere home in one piece, and have started trying it out. It sure feels well built, and the low focusing knobs are a great design feature. I've been using a condensor enlarger so far for my 6x6 and 35mm work, and some of the flatter negs which I print at G4 on it can't barely get enough contrast at full magenta filtration on the DV dichro head. I tested it w the ilford filters too, soo it seems to be a diffusion effect. Now, I know about the contrast difference between cond and diff sources, and have just re-read the relevant section in Ctein's book, but am still a bit surprised at how little contrast I'm getting at full strength. I still have to reprint my important 6x6 work to see how it looks, and before I remodel my very small darkroom to fit the DV and remove my Durst condenser, so I'm curious if this is something you just live with using a diffuser head, and from now on just aim for contrastier negs, or whether there's a way to squeeze more contrast out of thhe diffuser and therefore not have to keep the condenser around. Anyway, learning all the time, glad to get some experienced input,

GB

 

[Nick Zentena]

Does the DeVere have a filter drawer? If so stick a full blue filter in there. One of the Roscolux lighting filters. See if that helps. It's a relatively cheap thing to try.

 

[Marco Gilardetti]

Hello. I actually "live with it", as you say. I just progressively began to develop slightly more contrasty negatives year after year (not too much or grain will suffer).

With older negatives, when magenta is already at its maximum, I usually add an extra 40M filter in the filter's drawer. It usually works. You know: with VC papers, when you think you're at grade V, you may perhaps still have some headroom to go...

 

[Bob Carnie]

Something is out of place here.
I have condensor and the same enlarger you speak of.
Yes there is a difference between the two sources but not enough to cause the problems you are speaking of. If you are printing at full magenta and the other two filters dialed at 0 then something is wrong.
Your negatives would have to be impossible to print and by the sounds of it that is not the case.
I would open the head and make sure the dichroic *magenta * is dialing in all the way. Sometimes with diffusion enlargers the transport holding the dichroic gets stuck and is not working properly.
On my Deveere a normal Pyro negative, the Magenta should be somewhere around 45-85 magenta with cyan and yellow at 0.
For negs processed in D76 the Magenta should be anywhere from 20yellow only to 40 magenta only.

 

[don sigl]

My suggestion is to increase contrast with paper development. I would set up a two bath system with my normal developer and a high contrast developer. Start out with 50% in normal and 50% in the higher contrast developer. Adjust the proportions until you get the contrast you want. You could also combine this technique with split printing.
Split development provides a lot of flexibility, and was used by many old school printers before the advent of VC papers.

 

[gbenaim]

Nick: What effect would the blue filter have? Would a cc blue filter work?
Marco: Would a #5 ilford filter have a similar effect as the extra 40M in addition to the dichro head at 200M?
Bob: As I mentioned, I tested the contrast w the dichro head and w the Ilford filters, same filters I then used on the condenser.
Don: I use Dektol exclusively, which is a hig contrast dev. Is there something harder I can try?

 

[Marco Gilardetti]

On my Deveere a normal Pyro negative...

Bob, it's the Pyro negative which is not "normal" itself...

I agree that, with normally developed negatives in conventional developers, it may happen quite frequently to use a full magenta setting to print frames perhaps somewhat underexposed.

 

[Marco Gilardetti]

Marco: Would a #5 ilford filter have a similar effect as the extra 40M in addition to the dichro head at 200M?

No, it's much more dense, you'd loose a lot of light and you'd have to compensate with a longer exposure time. But if we talk about contrast, with that filter in the drawer and magenta set at 200, you'll sure reach the highest contrast available. Perform an experiment and see what you get.

I suggest as well to print comparative pictures with A) only the Ilford filters in the drawer and no dichroic filters on and B) with only the dichroic filters set at corresponding paper grade. You may find out that there's only an offset effect, and that to reach the contrast given by filter "III" you have to set the filters to the value given by grade -say- "IV" on the table.

I was talking about the M40 just in case you had the full filter set for colour papers... You don't necessarily need to have one. Generally speaking, any further increase in magenta would push up the contrast if you compensate the exposure time (SUPPOSED THERE IS STILL SOME CONTRAST HEADROOM).

 

[Bob Carnie]

Something is not making sense here.

My Deveres both max out at 200Magenta, I have never experienced a negative that requires this much filtration.
At 200mag only the image is shadow only black with completely blown out highlight and upper mid tone.
I still say there is something wrong with the dichroic.
Are you using white light when you are testing with the Ilford filters?
We use diffusion enlargers for skin tone images and we will bump up 1/2 grade to match the contrast and tonality.
Using only full magenta, and the image still being flat tells me something is wrong with the enlarger kit and not the source negative.

 

[gbenaim]

Bob, I used the ilford filters w white light. Whhat could be wrong w the enlarger?

 

[Nick Zentena]

Nick: What effect would the blue filter have? Would a cc blue filter work?

A blue filter will only pass blue light. So none of the low contrast green.

I posted on the LF forum that you should check the condition of the box. It may need relining. Can't hurt to look.

 

[Bob Carnie]

I don't know, I just find it extremely odd that you do not have enough contrast using either grade 5 ilford filter with white light or 200 magenta with the dichroics. The differences between condensor and diffusion enlargers are well noted but not extreme, something seems out of whack.

Bob, I used the ilford filters w white light. Whhat could be wrong w the enlarger?

 

[Jon Shiu]

Could it be the dektol has gone bad?

Jon

 

[gbenaim]

Jon, I did the comparison prints using the same batch of Dektol, recently mixed, and did the condenser after the diff.

 

[Paul Howell]

I use Dupont filters from the ealy 70s, the number 9 and 10 are blue and I get a true grade 4 uisng the #10. Dupont sets can be found on ebay for a song.


Paul

 

[tbm]

Several years ago, when I switched from a Saunders LPL condensor enlarger to a Saunders LPL dichroic enlarger, I noticed immediately that the latter did not give me the contrast the former did as easily although dust was suddenly no longer a rampant problem. However, when I attempt to print a negative that is problematic, I simply indulge in the split-grade technique which makes contrast truly pop! Numerous books containing sections on darkroom techniques describe how to use the split-grade technique but if you don't have one containing that simply perform a Google search and you will undoubtedly find numerous Web sites that describe how to do it.

Terry

 

[Ole]

I have two enlargers: An Opemus with colour head (diffusion), and a Durst with condensers. I recently printed a 6x9 neg in the Durst, then decided to crop it a lot and moved it over to the Opemus. I couldn't see any difference at all - with Ilford MG IV WT FB. Both were printed unfiltered.

 

[dancqu]

...read the relevant section in Ctein's book, but
am still a bit surprised at how little contrast I'm
getting at full strength.

You are assuming you've the same blue, condenser or
dichro. That is likely not the case. First there is condenser
vs diffusion. Most would say you've lost about a grade right
there. Second the paper you are using is being shorted a
portion of the blue spectrum needed and/or the light
source's longer wave length output is high and not
entirely filtered.

I suggest you try another paper. Perhaps one with
less overlap of blue and green sensitivity. BTW, what
are the bulbs in those two enlargers? Are you using
the same lens? Dan

 

[dancqu]

Hi all, Finally got the De Vere home in one piece, GB

Just recalled. De Vere 504 contrast problems. Read
all about it. Search this NG for, 504 papers . Dan

 

[Marco Gilardetti]

I have two enlargers: An Opemus with colour head (diffusion), and a Durst with condensers. I recently printed a 6x9 neg in the Durst, then decided to crop it a lot and moved it over to the Opemus. I couldn't see any difference at all - with Ilford MG IV WT FB. Both were printed unfiltered.

This brings new life to an old thought of mine - that is how much INHERENT difference in contrast there really is, and how much is instead caused by difference in lamp light's temperature, color of mirror box, tonality of the opaline glass itself...

 

[Ole]

The Opemus has a halogen bulb, the Durst an opal tungsten bulb. The difference in colour temperature could well be exactly enough to compensate for the difference between condenser and diffusion...

 

[dancqu]

This brings new life to an old thought of mine - that is how
much INHERENT difference in contrast there really is, and
how much is instead caused by difference in lamp light's
temperature, color of mirror box, tonality of the
opaline glass itself...

Off hand I believe a valid test could be made with
graded paper. With it's blue sensitive only emulsion
the variance in color from sources you've mentioned
should not be a factor.

A very narrow band deep blue filter and VC paper
might do. BTW, on that list as well, lenses. Dan

 

[Leon]

I'm having exactly the same problems as you - see this thread (there was a url link here which no longer exists) . I was typically getting grade 2 - 3/12 from my negs on the condensor (which is now gone BTW) and I'm often struggling to get good contrast from full magenta only on the devere. I've checked the operation of the filters, which is fine, so I've resigned myself to developing the film for more contrast - using an accutance developer like rodinal seems to keep the sharpness I was getting with the condensor, but the diffusion effect seems to take the graininess out somewhat.

 

[Woolliscroft]

Letting prints develop longer can make a surprising difference. I know most multigrades are supposed to develop fully in a minute, but letting them go to 2minutes does still help contrast and tonality.

 

[gbenaim]

Leon,

What explanations have you come up with for this problem?