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Cannot get b&w contrast with dichro head

Doc W

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I have a Devere 4x5 enlarger with a colour head which I use only for b&w. I calibrated the head a while ago with MGIV FB but no matter what I did with the yellow and magenta, I could not get any higher contrast than the equivalent of about a 3.5 grade. Is this a problem with the diffusion head or is it the paper itself? Can I solve the problem if I simply bypass the Y and M filters and use graded filters below the lens?
 
Yes but I am surprised that with Y and M you run out of grades at 3.5. What filtration did you use in a failed attempt to get grades 4 and 5/

pentaxuser
 
You can compare your maximum magenta to the Ilford #5 filter. The Ilford #5 filter is not a magenta filter (some propriatary spectrum) and in my experience it can produce more contrast than a magenta filter. Sometimes the extra contrast is very minimal or inconsequential, however.
One easy thing to check is to make sure your magenta filter completely covers the light source and there is no crack in the filter and no white light spilling over. Also, make sure the yellow filter moves completely out of the light source when set at zero.
 
The paper can produce the full range of grades, so the problem must lie with the enlarger/filtration. One thing to check is the lamp. If it is old, it could be giving out a more yellow light, and defeating your efforts to produce the harder grades. I don't know the capabilities of this particular head, but i would expect it to be able to reach higher than grade 3.5, although possibly not as high as grade 5. If you have access to a set of Multigrade filters, you could try using them first to see if your lamp is ok. One other problem is that dichroic filters in a colour head can fade. If the equipment has seen a lot of use, that could be the cause. Below the lens filters would be the cheap solution if that is the issue.
Alex
 
Or the film could be under-processed?
 
I use yellow and magenta together so I don't have to change my printing times. I calibrated this according to Ralph Lambrecht's book. I wanted to list the filter settings I use but the spacing goes wonky. However, I get a grade of about 3.5 with Magenta=58 and Yellow=14. No M/Y combination beyond that gives me any more contrast.

The filters are not cracked or broken in any way and the lamps are relatively new.
 

Are there diffusors or reflectors in the head that may have yellowed?
 
MattKing said:
Are there diffusors or reflectors in the head that may have yellowed?
Click to expand...

Not that I can see. Everything looks pretty normal.

Is that a common problem?
 
Doc W said:
Not that I can see. Everything looks pretty normal.

Is that a common problem?
Click to expand...

I don't know about your Devere specifically, but I have encountered it with other colour heads.

Are the filter dials attached correctly?
 
MattKing said:
I don't know about your Devere specifically, but I have encountered it with other colour heads.

Are the filter dials attached correctly?
Click to expand...

I have no idea. I assume they are. Let me just say that I can get good prints out of this head. I just can't get the contrast on MG IV up past about 3.5.

This an older Devere and was used in a college. I found another thread which discusses aging filters, so now I am not so sure that the filters are what they should be.

Take a look at this:

(there was a url link here which no longer exists)l
 

Are you sure you know what you are doing? Complaining about 'not enough contrast' when using sub-maximum magenta and any yellow in the filter pack is like asking why your prints are too dark when you give more exposure than needed.

More information on how to do your calibration is (there was a url link here which no longer exists) (specifically post #2) and the link below:


http://www.ilfordphoto.com/Webfiles/2010628932591755.pdf
 
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Doc W said:
However, I get a grade of about 3.5 with Magenta=58 and Yellow=14. No M/Y combination beyond that gives me any more contrast.
Click to expand...

What ic-r said. The maximum contrast your enlarger is going to deliver, whatever it is, will be obtained by setting magenta to the maximum and setting yellow to zero. Ilford's table of dual-color (M/Y) filter settings for color heads drives yellow to zero at the high-contrast end. Try maximizing M and zeroing out Y before you draw any conclusions about what your enlarger can do.
 

Oren, you and IC maybe onto something, i.e., I am not really clear what it is I am doing or, at the very least, I am not explaining it very well. I calibrated the head with combinations of yellow and magenta mainly so I would not have to retest exposure time every time I changed filtration. Perhaps I should have said that when combining yellow and magenta, I can't seem to get the contrast range I think I should have. Yes, I can use just one filter and get more contrast, but then the exposure time changes.
 
Doc W said:
Yes, I can use just one filter and get more contrast, but then the exposure time changes.
Click to expand...

That is true. The exposure time will change. That is the tradeoff you need to accept if you want to achieve the maximum contrast of which your enlarger is capable.

FWIW: Back when I was getting started in VC printing using filters in a filter drawer, I found that in practice the exposure required to achieve the best-looking print with a change in contrast was not necessarily the same as the exposure needed to match an arbitrarily selected gray tone, which is what the speed-matched filters and M/Y mix formulas do.

Since I moved to an enlarger with a color head, I've just used either M or Y as needed. I get rusty when I'm away from the darkroom for a while, but once I start printing again and get back in a groove, I get a feel for how exposures will vary, so I can quickly be in the right ballpark for exposing the test strips or test prints I need to be doing regardless.

As the saying goes, YMMV.
 

I have a dichro head that I use for this with that same paper and I've always felt that the numbers the data sheet give to set the head at are rather low...as in, a 55 M is supposed to be a 3 but it prints more like a two, or thereabouts, if you get my drift.

So I ignore the numbers and do what works. I've been doing this long enough I have achieved a certain consistency in my negs. Only took 40 years or so,
 
Apparently Ilford have used very different response in their new MGIV classic paper so you may need to redo your Y+M calibration if it was done using the old MGIV paper.
 
Yes, I can use just one filter and get more contrast, but then the exposure time changes.
Click to expand...

THE best investment I ever made was to get an RHD Analyser Pro, now sold by SDS. Not cheap, but really make the job of working with different papers, contrasts, times, easy. Doesn't matter what the enlarger is, when you calibrate a new paper you set it up for exposure times and contrast filter settings, and you can store up to 8 different papers in memory.

When you use the analyser you call up the paper you are using, take readings from the projected image without filters, and set where you want these to come out on the displayed (zone) grey scale. You adjust the time/contrast you want so the readings appear in the right place. Press the exposure button and that's it. The skill is getting used to taking the readings and placing them where you want on the displayed scale. 8/10 I get a print I am satisfied with first time. NO TEST STRIPS!

Not particularly trying to be an advert for the analyser, but when I read about people fighting contrast/exposure settings, I realise what an excellent device this is.

This an older Devere and was used in a college. I found another thread which discusses aging filters
Click to expand...

If they are dichro filters they cannot fade - there is no colour in them in the first place.
 
I use the Y and M combinations for the same reasons you state on my LPL, and I'm able to get a good grade 4, going beyond that pretty much requires just magenta filtration.
I've not tried Ralph's method, but when I first got the enlarger I made a set of comparison prints using the full range of MG filters, and another using the combination filtering from Ilford's data sheet.
In general, I found the color head filtration was about 1/2 grade softer than the MG filters.

Since grades are kind of arbitrary with VC papers anyway I didn't go any further in trying to calibrate, I just add or reduce contrast as needed, and I've rarely had a need to go beyond what amounts to grade 3.5.

All that said, I'd try some tests with just magenta filtration and see what happens. Getting up to 3.5 with the combination filtering should be fine for most work, and your tests will be a good basis for venturing beyond that when you need to.
 
I get full Grade 00 to Grade 5 on my Durst L1200 using inbuilt dichroic filters. LPL (reported by many) only goes upto around G4 so it does vary from enlarger to enlarger and according to age as the old filtration was designed for older grade specs I think.
 
Also, you should consider that the contrast in a print is a combination of negative contrast curve and filter modification. You can alter the parameters of both. i.e. If you increase your film contrast curve steepness it will increas the print contrast too. This has the benefit of allowing faster film speed and generally a shorter film toe due to the increased film development.

So its a balance of film dev and resulting film contrast combined with dichroic filter settings. And that means that saying that an enalrger isn't capable of G5 is not quite correct as the real culprit can easily be standard development which isn't sufficient for your particular enlarger to allow G5. Depends which viewpoint you come at it from.

The test you should be doing is to print a step wedge without any filtration and then a second with your G2 Y+M settings and the two prints should be identical (almost) in that when you align a step from each with the same tone, all the other steps should align with a matching tone. i.e. they both provide the same range(no of steps) from black to white. If that isn't happening then your Y+M for G2 is wrong which probably means all your other Y+M settings are wrong too. Once you have that correct then you can assess if your Y+M settings are really as they should be.

Note: I looked at ralphs Y+M calibration document a very long time ago (before his book was published) and tried it for myself. I concluded that whilst it kind of works it is also misleading because the results vary depending on your starting point. If you redo his test using the results from your initial test as the starting point then you get a different set of results from your first test which tells you that the resulting target is indeterminate. I'm not going to say any more on that. Fortunately I have enlarger which is already well calibrated.
 
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I know of no subtractive color head which will reach a true contrast range of 4.
 
Jim Noel said:
I know of no subtractive color head which will reach a true contrast range of 4.
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A durst L1200 with CLS501 head will as has been verified by myself and several other people on this and other forums.
 
I've never liked VC papers but when I tried them for awhile (decades ago) with a dichroic head I used ND filters in the drawer to to keep my times constant.
 
There seems to be a wide range of opinion and experience on this. I have a Stouffer 31 step wedge and I will do some testing early next week to see if the paper yields more contrast with only a single filter, rather than the M/Y combination. I really need the M/Y combo for speed-matching, but I want to see if I can get higher contrast with M only.

Thanks for all the replies.

Just for the record, when I did the tests a while back,
- the lens was clean
- chemistry was fresh
- paper was fresh
- I used a step wedge for the tests (so the fault was not in the negative)
 
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