How are 162Y 0M and 200Y the same?

[timbo10ca]

I purchased an RH Designs timer and meter, and I'm about to calibrate it. I was looking over the contrast grades again (I'd always used just Magenta because it was easier, and I still don't understand the reason for using Magenta and Yellow), and I thought I should get things straightened out before I go further. I'm using Ilford paper (RC) and a dichroic enlarger. Why are the dual filter numbers different than the single for grade OO, if they are doing the exact same thing?

Tim

 

[Eric Rose]

you should check out the article Les McLean wrote on split grade printing. As far as your question is concerned I can guess that after 162Y there is no real difference in the "soft" value. That is to say all your really doing is adding neutral density.

A quick email to RH Designs might help to. Once you find out share their response with us.

ER

 

[Roger Hicks]

(I'd always used just Magenta because it was easier, and I still don't understand the reason for using Magenta and Yellow)

Tim

The paper is sensitive to blue and green. Yellow blocks blue light; magenta blocks green light. That's why you need both.

Cheers,

R.

 

[Nick Zentena]

Dual filter numbers are speed matched. So grade 3 will have basically the same exposure time of grade 2.

If you use the single filter numbers the exposure time will vary.

 

[pentaxuser]

Looking at the leaflet issued with Ilford Multigrade IV RC paper, I notice that at either extreme(grade 0 and grade 5) the dual filtration becomes single filtration and in fact come close to single filtration the closer to 0 or 5 one gets. So presumably speed matching is only possible around the middle grades.

I also noticed that based on my B&W analyser's probe, speed matching occurs within quite a narrow range.

I couldn't in fact get exact speed matching in the sense of identical exposure at any grade i.e. even grade 2, 2.5 and 3 had slightly different exposure times although the differences were small enough to make only a very marginal difference to the appearance of the print in exposure terms.

As any changes to filtration is reflected in the analyser's reading, one could argue that lack of speed matching isn't important and on that basis neither is it important whether one uses Ilford's single filtration for grades or its dual filtration.

I started off using single filtration and now use dual filtration for grades but I would be hard pressed to say that prints at say grade 3 with dual filtration are better than grade 3 with single filtration.

There may be flaws in the above argument and if so I'd appreciate anyone pointing this out. It'll help me and I hope advance the general discussion on the subject.

Thanks

pentaxuser

 

[Ole]

Yet another argument for the Meopta colour head - I've got an extra ND filter. Using that and the aperture, I get perfectly consistent printing times across the full range possible with MG IV.

Test print without Y/M, but full (more usually half) ND. Read detailed highligh value with the EM-10. Adjust filtration for grade, reduce ND until the EM-10 reads exactly the same. And that's basically it...

 

[timbo10ca]

Dual filter numbers are speed matched. So grade 3 will have basically the same exposure time of grade 2.

If you use the single filter numbers the exposure time will vary.

??????

Wow- this discussion is way over my head. Looks like I gotta do some outside research to figure out what you guys are talking about. It sounds like this is a basic aspect to printing that I've not learned about. I understand how paper has a speed sensitivity like film, and you can match a paper to a negative based on their characteristics (thanks to a recent thread), but that's about it. Ole- you totally lost me

Tim

 

[reellis67]

...Read detailed highligh value with the EM-10. Adjust filtration for grade, reduce ND until the EM-10 reads exactly the same. And that's basically it...

I was beginning to think I was the only one using an EM-10. Glad you brought it up...

- Randy

 

[Nick Zentena]

??????

Wow- this discussion is way over my head.

Think of it this way.

With each single filter it's like using a different power bulb in the enlarger. You'll have less/more light depending on how strong the filter is.

Using dual filters you'll hopefully have the same amount of light getting past the filters.

Now this doesn't work at either extreme. Both extremes are mostly one colour or the other.

But for the more commonly used middle grades dual filters trying to even out the differences.

 

[Bruce Osgood]

I was beginning to think I was the only one using an EM-10. Glad you brought it up...

- Randy

Wouldn't be caught in the darkroom without mine.

 

[David Brown]

Tim:

Your title question: "How are 162Y 0M and 200Y the same?"

If I read this correctly, this has nothing (directly) to do with the RH timer or F stop printing. These are filter numbers given in documentation for Ilford RC paper. One chart (for individual yellow OR magenta filters) says that grade 00 is "199 Y". Then, in the chart for using both filters together (to achieve consistent exposures, as has been discussed) gives grade 00 as 162 Y and 0 M.

OK, given that zero magenta filtration is nothing, how does 199 Y = 162 Y? :confused:

I don't know - and have always wondered that myself.

 

[Ole]

OK, given that zero magenta filtration is nothing, how does 199 Y = 162 Y? :confused:

I don't know - and have always wondered that myself.

It isn't - quite. But while maintaining the consistent exposure time across the grades the softest filtration possible is 162Y. 200Y is even softer, but would require exposure adjustment, and the whole point of the two-filter thingy is to get consistent exposure, or at least whole-stop adjustments.

It's been entertaining to watch this thread - and waiting to see if anyone could come up with an answer!

 

[timbo10ca]

Think of it this way.

With each single filter it's like using a different power bulb in the enlarger. You'll have less/more light depending on how strong the filter is.

Using dual filters you'll hopefully have the same amount of light getting past the filters.

Now this doesn't work at either extreme. Both extremes are mostly one colour or the other.

But for the more commonly used middle grades dual filters trying to even out the differences.

A-HA!!! The light bulb goes on, so to speak. Thanks Nick. Now, why is Ilford essentially saying that OO is 162Y AND 199Y, and at the other end 4.5 is 140M and 150M? These are the numbers in their tables, depending on whether single or dual filtration is used. I don't see why they don't use the same values- they had to come up with them somehow.

Tim

 

[timbo10ca]

It isn't - quite. But while maintaining the consistent exposure time across the grades the softest filtration possible is 162Y. 200Y is even softer, but would require exposure adjustment, and the whole point of the two-filter thingy is to get consistent exposure, or at least whole-stop adjustments.

It's been entertaining to watch this thread - and waiting to see if anyone could come up with an answer!

David- you're correct in your interpretation of my question- I only mention the RH designs timer because they calibrate it to Ilford MGIV and reproduce the numbers in their manual.

Ole- you're a wiley wascal What you say makes sense though.

Tim

 

[Nick Zentena]

There was a thread on this a few weeks back. Either here or on the Large format forum?

I think the best guess was Ilford is more worried about speed matching then the slight difference in grades. My guess is the single filter numbers may be closer to the actual grades. But the dual filter numbers are more of a compromise.

OTOH the exact grade you get is going to be the result of other factors to.

 

[David Brown]

Tim: glad we finally figured this out.

Ole: thanks for me, too.

I don't know if we discussed this exact question recently, but I do remember numerous threads about dicroic filter settings for VC grades. One thing I must say, though, (and not to confuse things) is that it is all relative. On the Ilford charts for instance, 5M is gr 2.5 and 25M is gr 3. But sometimes a negative needs 10M! Ya know?

 

[tleirtro]

You might also take a look at this article http://www.butzi.net/articles/vcce.htm
by Paul Butzi about how to do your own calibration of the filters using a colour head.

Thor Egil

 

[Roger Hicks]

Just to add to the fun, a grade 5 discrete filter gives a harder grade 5 than any dichroic head I know of (including dedicated monochrome heads) and grade 5 paper is harder still.

Cheers,

R.

 

[fschifano]

But there is one more "gotcha" in this whole thing that no one has mentioned. Dichro color heads from different manufacturers are not all calibrated the same way. For example; 50M on a Durst machine may not be the same as 50M on a Beseler machine, which in turn may not be the same as 50M on a Meopta machine. All this can be very, very tedious to work out. My suggestion is to use the paper manufacturer's recommendation as a starting point, then fine tune it to your needs.

 

[Ole]

... and even better, the dichroic filters fade with age. So what was 50M on a new Durst machine may not be the same after some years - on the same machine.

So use all guidelines and recommendations as exactly what they are - guidelines and recommendations.

 

[Nick Zentena]

Or the white foam yellows

 

[haris]

Buy below the lens or gelatine filters for enlarger's filter drawer and forget about enlarger's head filtering problems ...