Problem with Kentmere Select VC lustre

[Richard62]

I have had a problem with Kentmere VC Select Fine Lustre (7x5)
Equipment used
Meopta Magnifax 4 with multigrade head
Ilford multigrade developer
Fotospeed stop bath and fixer
Nikon 63mm enlarger lens

I have been doing some test prints to find the correct exposure time for the kentmere paper. After a few tests I got a decent grade 2 print at f11 and time of 20 seconds.
As the multgrade head has a neutral density filter built into the colour filters for the different grades there should be no (significant) difference in the exposure time when printing with harder grades. However when I tried printing the same image at grades 3 -5 all that happened was that the images did get a bit more contrasty but also got significantly darker as the grade increased. I made no changes to the aperture or exposure time. I even used an Ilford EM10 meter to check the exposure and it actually showed a slight reduction in image brightness as the grade increased (which should have priduce a lighter print!!).
I then used Ilford MGIV pearl to produce a grade 1 and grade 5 print with the same exposure settings. This did exactly what it should have done - significant increase in contrast with a very small change in the brightness of the print.
As a final check I went back to the Kentmere and did another grade 2 and 5 with the same settings and the original darkening of image occurred again.
The Kentmere paper was purchased Nov 2023 and the MGIV purchased in 2009 and kept in a freezer, so I would have expected problems with the MGIV rather than the Kentmere(!)
Has anyone else experienced this problem or similar?
An explanation would be gratefully received.
Thanks

 

[pentaxuser]

It might help if you were to show us examples of the two papers to which you refer

Thanks

pentaxuser

 

[Richard62]

Attached a couple of images from each paper. Hope that helps. Yesterday I produced a great split grade print of my granddaughter on MGIV so doesn't seem to any problems with the multigrade enlarger head or the MGIV paper..

 

[koraks]

there should be no (significant) difference in the exposure time when printing with harder grades

For which part of the tonal scale? Shadows, highlights, midtones? And are those filters calibrated/intended for the paper you use, or some paper that existed back when the multigrade head was engineered?

it actually showed a slight reduction in image brightness as the grade increased (which should have priduce a lighter print!!).

Assuming that the EM10's spectral response matches the paper's response, and also within the caveat I indicated above. So it's not very surprising that you find that in practice, it doesn't pan out this way.

The practical shortcut/conclusion to all this is to do what generations of photographers have done before you: make test strips when switching to a different grade.

 

[Richard62]

Thanks for the replies. The MG head has filters designed for modern multigrade papers MGIV etc, not the very early (first) MG papers whcih I believe had a very different coloured filter set. They have worked well with the other boxes of Kentmere VC Select I have, (in fact the Kentmere is my prefered paper). The main reason for my use of an enlarger meter is to adjust exposure when changing the size of the print. For this I use the meter with a diffuser under the lens (from a paterson meter) to get an average reading-and adjust the exposure when so that the meter shows a green light at the new print size - this has always worked well for me. I'll pursue the idea of test strips for different grades and see how that works out. Thanks again.

 

[F4U]

This is not the good old days any more, I'm afraid. Today it's pot luck on photo supplies, even of the same brand. These photos are an example. Everything now is all over the place, even from batch to batch, and even the same manufacturer. All you can really do any more is stick to the same products as best you can, and hope the same manufacturer is not really just a broker. And keep your shutters and light meters accurate, so you can TRY to achieve a certain dependability in the making of the negative, so you can stay at paper grade 2 or 3. From what I can tell, these photos prove my point that juggling between brands and types these days turn you into a lab technician when you just wanted to be a photographer using known dependable supplies. I bet the OP is pulling his hair out trying to figure out what's what.

 

[MattKing]

FWIW, here is what the datasheets show:
Kentmere:

Ilford MGIV and "V":

If nothing else, you will note that there is considerably more of a difference in sensitivity (4x vs. 2x) between the 00 filter and 5 filter for the Ilford paper than there is for the Kentmere.
And of course, the Kentmere paper itself is twice as sensitive as the Ilford.
All of those speeds will be based on a particular tone - IIRC, nearer to a highlight tone than a shadow.

 

[bedrof]

FWIW, here is what the datasheets show:
Kentmere:
View attachment 407651

Ilford MGIV and "V":
View attachment 407652

If nothing else, you will note that there is considerably more of a difference in sensitivity (4x vs. 2x) between the 00 filter and 5 filter for the Ilford paper than there is for the Kentmere.
And of course, the Kentmere paper itself is twice as sensitive as the Ilford.
All of those speeds will be based on a particular tone - IIRC, nearer to a highlight tone than a shadow.

I believe you are a bit mistaken here - look at the ISO Speed (P) chart in the Ilford datasheet, that is what should be considered in comparison to Kentmere paper properties.

 

[Lachlan Young]

A quick look at the curve difference between current MGV and the old MGIV will illustrate what's going on in terms of speed/ grade relationships and where the exposure constant sits/ has moved to. In other words, rather than relying on old habits and guesses, do a test strip. Kentmere is probably not wildly dissimilar to current Ilford paper curves.

I've seen several people IRL get themselves into a real mess because of poor paper exposure-to-grade understanding (with good negs), then once they bin their wrong assumptions & take a step back and make a new test strip, it all lands where it should.

 

[bedrof]

where the exposure constant sits/ has moved to

@Lachlan Young Could you please clarify this fragment? What is this constant?

 

[MattKing]

I believe you are a bit mistaken here - look at the ISO Speed (P) chart in the Ilford datasheet, that is what should be considered in comparison to Kentmere paper properties.
View attachment 407660

Fascinating - my table also came from a datasheet posted on the Ilford Photo website. I wonder which is right.

 

[reddesert]

IIRC, Ilford originally designed its multigrade filters and paper so that grades 0-3 would require the same exposure and grades 4-5 would require twice as much. Look at the speeds listed in the line for "MG IV DELUXE RC" in the table bedrof posted (look at any of the not-"NEW" lines in that table, and note they are different from the table MattKing posted). IIRC this was a slight advance over Kodak Polycontrast filters and paper where there was no speed equivalence.

But in practice, the grades are different contrasts, so "same exposure" means same exposure to reach some particular density, but the other densities are going to fall somewhere else. So you could only use this same exposure as an approximate guide, even when the papers and filters matched. If you want to control highlights through shadows you still ought to do a test strip. The approximate 1x or 2x of exposure was just approximate and told you roughly what times to try for the test strip. I don't think there is anything wrong with the Kentmere paper.