Ilford MGFB Classic and MGIV RC Contrast

[Nathan King]

I use Ilford MGIV RC Pearl paper for contact sheets and MGFB Classic fiber paper for enlargements. I have noticed that the fiber has about one grade more contrast using the same Ilford filter. Is this normal behavior? I develop the RC for one minute and fiber for two minutes per Ilford instructions.

 

[pentaxuser]

Never used Ilford FB but I had always understood that the VC emulsion was essentially the same and designed to produce the same grades with the same filters.

I don't recall others saying what you are saying but I may be wrong. Might it be the difference in surfaces that appears to give a different grade? For instance RC Satin always seems to be of lower contrast that its Pearl cousin

I wonder what Ilford has to say on this?

pentaxuser

 

[MattKing]

The new "Classic" is a replacement for the former FB multi-contrast paper, whereas the RC paper has not recently been changed.

I would expect that the changes to the FB papers will mean that some people who use both RC and FB will have to re-calibrate their procedures.

 

[Roger Cole]

I use Ilford MGIV RC Pearl paper for contact sheets and MGFB Classic fiber paper for enlargements. I have noticed that the fiber has about one grade more contrast using the same Ilford filter. Is this normal behavior? I develop the RC for one minute and fiber for two minutes per Ilford instructions.

I bet you use a condenser enlarger, no?

Contact printing, even when done under a condenser light source, produces softer results than enlarging under a condenser light source. The difference is often - tada, about one paper grade. Thus those who develop large sheet film intending to contact print generally develop to a higher contrast more like that of those who print with diffusion (color head or VC head, cold light head etc.) enlargers, while those who print with condenser heads develop for less contrast, or simply print with a softer filter or paper.

PS: Here's a suggestion though it may lead to even higher contrast from the FB paper - try developing the FB longer, a minimum of three and as much as five minutes. I've not seen a neutral or neutral/cool paper yet that I didn't think benefited from a development time longer than typically recommended by manufacturers, though warm tone papers may get less warm if you try it with them. I haven't tried to prove that it leads to an actual increase in D-max, but it certainly gives prints that look subjectively "richer" to me.

 

[cliveh]

I would ask the question why do you use a different paper for contact printing and enlarging?

 

[Roger Cole]

I do the same thing. Because RC is quite a bit cheaper, because it lays flat with no fuss, because it's easy to handle and wash, and it doesn't have to look as good or last forever.

I'd wonder why on earth anyone would use a premium FB paper for contact proofs? (I don't mean display contact prints of larger negatives, obviously.)

 

[tkamiya]

Nathan,

I find the difference between the two is not just the contrast or apparent contrast. To me, black on FB looks darker than black on RC Pearl. White on the other hand looks brighter on RC than FB. I think the reflectivity of the surface is probably the cause of it. Behind glass though, they look pretty much the same.

Once I start on one paper, I usually stick with that paper. In the beginning, I tried to experiment on RC first then print on FB. It has been frustrating experience to print one to look like the other. That didn't help me much and didn't save any paper. YMMV....

 

[Roger Cole]

I agree about not trying to make full sizes work prints, experimentation prints, intermediate prints or whatever on different papers from the final print. That's more frustrating than it's worth by far in my experience too. But the differences between contacts and significant enlargements, especially from 35mm or MF, tend to dwarf the paper differences anyway. The contact just shows me what's on the negative. I switch to the final paper when I start trying to coax it out.


Sent from my iPhone using Tapatalk and 100% recycled electrons - because I care.

 

[Nathan King]

Thank you all for your input. I was able to do some troubleshooting last night. First, I do use a diffusion enlarger (Beseler VC head) but use the white light and place Ilford filters under the lens because the VC head dims the light way too much.

I enlarged a 6x7 negative to 8x10 using a grade 2 filter. Using both RC and fiber. The prints had the same values in the highlights, but the shadows were much darker and mid tones more separated with the fiber. I made another enlargement on resin coated paper with grade 3 light. The resulting print was almost identical to the grade 2 fiber print.

 

[Nathan King]

This is correct. MG Classic is not the same as MGIV. Contrast, curve shape, grade spacing, response to MG filters vs VC heads are different. MG Classic also has higher emulsion speed, different image colour and different response to toners.

There's the answer then. I should not expect them to be similar. The difference really is quite large!!

 

[RobC]

all papers lose natural contrast over time. When the paper is very near to its production date it will have higher contrast and reach a higher Dmax than year old paper which will have higher contrast than 2 year old paper etc.

So unless you are testing papers which have production close to each other and were stored in same conditions then even though they may both be MGIV I wouldn't expect them to give the same curves.

I doubt very much that the curves for MGIV classic have changed much if at all from the old MGIV but I could be wrong. G2 is G2 meaning it must have a certain slope between the min and max measuring points so it will be similar to old paper. Same for any other grade you care to set with your filtration.

So unless Ilford have deliberately changed the curve to more of S shape or given it a long toe or long shoulder, all of which I doubt but haven't tested, then my bet is you are comparing old paper against new paper (agewise).

 

[RobC]

They have indeed changed the curve shape. Grade spacing has also changed (by design).

Looks like I'll have to do some more print curves tests then. Has the speed point changed?

 

[RobC]

Actually after asking has the speed point changed it dawned on me that the speed point (meaning where the curves cross) is largely a function of the filtration.

The last set of MGIV FB tests I did with very new paper showed that using Ilford under the lens filters I got a speed point density of 0.3 logD whereas using my Durst L1200 dichroic filters it was 0.7 logD.

So yours and everyone elses speed point will vary according to filtration used. And importantly it will vary from enlarger to enlarger as you can't rely on your enlarger filter dial units being close to accurate for anything without calibration.

The main thing from my perspective is that using Ilfords filters or my durst settings for the paper, the curves all cross at the same print density which if known makes life far more predicatable when altering grade.

don't know when I'll get round to doing any testing as darkroom is dismantled whilst trying to move house so don't hold your breath while waiting.

p.s. I tend to take Ilfords charts with a pinch of salt. I think they are more illustrative than accurately taken from real lab tests. But having said that, using Ilfford filters with the old MGIV FB, each grade crossed at same print density.

 

[RobC]

Michael,

Is this the post you are referring too?

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

That looks to me like you have used zero as the origin for each grade which is not what I do.

I use grade 00 as my starting point and print my transmission step until it fits within the paper. i.e. I have steps as both ends which are not getting lighter or darker. Remove those from the data so I don't get horizontal lines in the graph.

Then I print all other grades with same time and development. They will all fit because higher than 00 will have a shorter scale than 00.

Then I put them into my graphing software making very sure that each transmission step is aligned in same column of input data.

If you put all the 0.1 readings from my test in the same input data column then the speed point of the grades is not found/shown in the graph. So the readings must be kept in the same column for each transmission step and NOT a column for the lowest reading which is what I think you have done by the look of it.

The test without filtration is just placed in the graph so I can see how it compares to G2 filtration which was almost exact same.

The bottom line of data is the transmission steps in 1/3 steps. The line above that was without filtration (but has been positioned to line up with G2 row further above.

so when you create your graph like this you see the grade/paper speed point which in this case was 0.3

Obviously this graph is not much use for new Classic paper except to compare (when I eventually test it).
View attachment 105788

p.s. I also think using a step wedge with 1/3 stop steps and smoothed makes for a much better graph.

and just for completeness here is the Durst L1200 Y+M test. Again not much use now except for comparison.
View attachment 105789

 

[Simon R Galley]

Dear RobC,

Not a criticism in anyway, but all the tests we do on everything are 'real' lab tests, every batch, film and paper, and for our tech service sign offs for the launch of CLASSIC FB hundreds ( if not into the thousands ) of individual tests across every aspect not just sensitivity and 'calibration' and the production of the TI guides and user information, real prints, real evaluation, every type of application, I know I have seen them all... producing a new FB printing paper with the ILFORD name on it is a really big deal.

Simon ILFORD Photo / HARMAN technology Limited :

 

[M Carter]

In praise of RC - I usually get to know a negative with 8x10 RC, play with contrast, split filtering, dodge masks, etc. I find a good deal of that translates - not the specifics, but a sense of "familiarity" I suppose. I use much less fiber in 11x14 or 16x20 when I take that path.

It's not like you can recalculate exposure from the new enlarger height and then instantly have a great print... but it does go a long way. YMMV of course...

 

[RobC]

Hi Rob - the procedure you outlined is exactly how I do it, which is why my results puzzle me. For example, if you look at my plot for MGIV using under-the-lens Ilford MG filters (they were brand new at the time), my crossover is at a reflection density close to 0.3, so not far off from your data. What bothers me about that is, if grades 00-3.5 are speed-matched at ISO speed, the crossover should have been at a density around 0.6, not 0.3. With Classic, my results were further off, with a crossover point at a very low reflection density. This would actually be a more ideal speed-match point from my personal printing perspective than the ISO density, but I doubt my data is correct since in Ilford's tech sheet for Classic the crossover is clearly at a density of ~0.6, implying they are ISO speed-matched.

Perhaps it's simply a difference arising from the spectral output of the light source, but it just bothered me I was so far off on the crossover for Classic, since the curves themselves looked quite close to Ilford's.

Until I get to test Classic paper and see if my results are similar to yours or not then I can't really make any comment. If you are using same procedure as me and getting those results then it does look a bit odd, especially as Simon is saying the Ilford PDF Graph is correct.

But then the old MGIV FB PDF file shows grades crossing at 0.6 (close to my Durst dichroic filters) but not close to my Ilford filters at 0.3.

It doesn't really matter, whats important is that you know what your paper filter combo is doing and then use that to good effect. Where the PDF says the grades cross is fairly irrelvant since that is always trumped by your own evaluation tests..

 

[DREW WILEY]

Agreed. MGIV FB and Classic FB are very different animals in numerous respects. Different look. Better highlight gradation and toning options
with Classic - a richer paper in general - but also a tad fussier. Likewise the new Cooltone.

 

[Roger Cole]

In praise of RC - I usually get to know a negative with 8x10 RC, play with contrast, split filtering, dodge masks, etc. I find a good deal of that translates - not the specifics, but a sense of "familiarity" I suppose. I use much less fiber in 11x14 or 16x20 when I take that path.

It's not like you can recalculate exposure from the new enlarger height and then instantly have a great print... but it does go a long way. YMMV of course...

Actually you can recalculate the exposure and nail it when changing magnifications. I used to have the formula for this tacked up on my darkroom wall. It seems to have gone missing though.