color dichroic head......

[BigSteveG]

is it possible to print B&W using this type of head? If so, are there caveats/problems associated with this application? Enquiring mind wants to know.....My Darkroom gas is overwhelming these days!!!!!

 

[mhv]

Caveats: you might spend a lot of time calibrating your head to have constant exposure/filtration.

Have a look at the following article by Paul Butzi to understand what I mean:
http://www.butzi.net/articles/vcce.htm

You can do it in a much simple manner: yellow to reduce contrast, magenta to increase it, but you will have to constantly adjust your printing time.

I use a Vivitar VI with dichro head, and after some trials I decided not to use the filtration, but rather rely on Ilford filters. My rationale was twofold:

* First, the Ilford filters are calibrated so that exposure is constant from grades 00 to 3.5, and then from 4 to 5. I don't need one-sixths of a grade. I use that finesse for color work, but my B&W is just fine with half-grades.

* Second, if you want proper contrast on a VC paper, let's say for a grade 2, you will need to mix together yellow and magenta. Problem is you can have enough of one, but not enough of the other. I.e. while your overall contrast will be OK, your tonalities will be all over the board because you don't have the proper balance of Y+M. A VC printing filter is a proper, laboratory-tested and calibrated combination of Y and M. I prefer to leave it to the pros.

 

[BigSteveG]

Thanks for the reply. So now my understanding is such: I can use a set Ilford filters instead of the Dichro head's built in filtrattion system? If so, my problems should be solved.

 

[mhv]

Well, you will have less many headaches if you use the Ilford filters. The dichro head works, but it requires a lot of fiddling to get it right.

 

[pau3]

Of course it works. All paper manufacturers include a guide to select the appropriate setting in your dichroic head to obtain a certain grade. It is clear that
this may not be exact, but, is there something exact in photography?
You may need some calibration. However, to obtain a grade 2 with
VC paper you only need to use the dichroic head without filter (in my LPL670
is easy).

I think that you will need callibration if you want to keep the times for
middle tones invariant while changing grades. If you do not care about that
and callibrate for maximum black, then it doesn't matter.

Pau

 

[mhv]

I don't know if it's just me, but I never managed to get a grade 2 with any printing head without filtration. I did the test, comparing "naked" light vs. using the G2 filter from Ilford, and the contrast was never the same...

 

[sepiareverb]

I have a gang darkroom with several dichro heads, and filtration values are different on the different age heads, but using only one head/enlarger it would be pretty easy. The worst part for sure is the lack of any consistency with exposure time when switching grades. I had a student try and figure out how much blue to add to keep times consistent. He gave up long after I would have.

Using the Ilford filters will work fine keep the built-in filters at 0, and just lay the filters over the negative carrier. I printed with a cold-light head using the filters this way for years. As long as you are careful with the filters to prevent drastic scratches this is a simpler method.

 

[Resoman]

I do all my VC printing with a color dichroic enlarger head, and I wouldn't have it any other way.

I've had my Saunders/LPL 4550 enlarger for about ten years, and ordered it with the dichroic head, even though I've never been interested in color printing. I was very pleased printing VC paper with this enlarger, but I bought the Saunders VCCE module a year or so later, assuming I'd prefer it. I used the VCCE setup for a month or so, but didn't find it superior in any way and my exposures were much longer than with the dichroic. So, I went back to the dichroic head and have used it ever since.

I generally make an initial test with no filtration, add magenta if I need more contrast, or yellow If I need less. Adding filtration requires an exposure increase, of course, and I find these adjustments very intuitive and easy to make.

I tweak my settings until density and contrast are as I want them, and I feel I can get to that point quicker with the dichroic head than with any other technique I've used. I've got a set of VC filters around here somewhere, but I'd be very frustrated using them and being restricted to half-grade adjustments in contrast.

It's true that I don't know what equivalent VC filter I'd be using but, why should I care? I'm only interested in the appearance of my finished print.

I suppose there a a lot of ways to print on VC papers, but using a dichroic color head is my strong preference.

Regards,

Gary,

East Snook, TX

 

[Roger Hicks]

Gary is no doubt right for some people -- an enormous amount depends on how your mind/eye works -- but I have to say, I find VC heads significantly easier. Our main enlargers have dial-in VC heads (Meopta Magifax) and the one with the color head (MPP 5x7 with De Vere head) is harder work. For me (and my wife).

If you need very hard grades the followig are (usually) steadily harder:

Dichroic
VC head
Discrete filters
Graded paper

but we're only talking about grade 4 and harder here.

Cheers,

R.

 

[palec]

Meopta site and Kentmere instructions shows that with combination of Yellow and Magenta you can get speed matching grades. The values vary a bit, but are very similar:

http://www.meopta.cz/index.php?id=121&lang=en

 

[dadsm3]

I have a Saunders/LPL D6700 di-chroic, and for Ilford VC paper on the Ilford site it says that I should use the Kodak settings, which say for a filter setting of 2 1/2 (my personal starting point) I should set it at 32Y/42M. Problem is exposure is about 45 seconds at F8, which is a lot longer than what I was used to using slide-in filters at my college course.
Issue is I've received about 200 sheets of Agfa 'Multi-contrast Premium MCP 312 RC Semi-Matt' as a gift, and I've found that just playing with dichroics is a little harder than sliding in a different filter....
Can anyone steer me to a site that will give me the dichroic starting points for this paper?
Sorry for the hijack BigSteve. I can fax you my chart for Ilford papers, but the info is on their site. For some reason they only list Durst, Kodak, and Leitz Focomat, but somewhere I found out that Saunders' settings are under Kodak's, but it was a PIA.

 

[pau3]

dadsm3,
if you have too long exposure time with double filtration, you
may try to use simple filtration. In the Ilford leaflet you will have
the appropriate settings for the dichroic head. I use also a LPL with
dichroic head, and I use simple filtration. Also, in this way I know if I'm
using a harder or a softer grade (which is something that is not clear
when you use double filtration). It is true that, then, exposure time changes
from one grade to another, but with a test strip to get maximum black, you will get the time forever.

The settings for Agfa 'Multi-contrast Premium MCP 312 RC Semi-Matt',
from an Agfa document I have, are the following, for Kodak simple filtration:

0 - 80Y
1/2 - 55Y
1 - 30Y
1 1/2 - 15Y
2 - -
2 1/2 - 25M
3 - 40M
3 1/2 - 65M
4 - 100M
4 1/2 - 150M
5 - 200M

If you want, I can send you a copy of the Agfa document.
Pau

 

[mikeh]

Thanks Pau (I'm Mikeh at work). I was unaware of the single filtration method with dichroics and will certainly give it a shot.
Really appreciate the info....I may bother you again for single filtration info for Ilford paper once this Agfa runs out.
It will be interesting to see the difference between the two methods, if any.
Thanks again,
Mikeh (dadsm3)