Ilford Paper Question
I did some minor testing that gave me some surprised results: Saunders 4500 Enlarger, VCCE Head; Ilford MGIV FB Glossy Paper; Freshly made Dektol 1:2 Developer at 70F; 3 minute development time, water stop, fixed in Kodak Rapid fixer without hardener; 4x5 Stouffer Step Wedge as a negative; Printed using the VCCE #2 Filter. 8x10, full frame print.
I was printing my Step wedge in preparation for calibrating a RH Designs Zonemaster. So I print it out, getting Area 1 and 2 to be the same ( black ) density) after dry down, and the top area that still has any response to the light is Area 11. Area 12 is totally white, no sign of any activity.
To me, his means I am getting 10 half steps ( 5 F-Stops) of activity on my paper. I find this a bit low, as I would expect the paper to be able to handle a few more zones of light.
Does this sound right ? Should I be getting more zones in the print than 5 with this combination? SHould I change something to get more dynamic range in the print?
Ilford paper question
Frank, I have not tested Ilford FB but here are some results with other papers for comparison.
Agfa MCC111 Multicontrast Classic with a Stouffer half stop step wedge and my LPL ( Saunders in USA ) 4x5 enlarger at grade 2 gives 12 steps visible,
counting the first step as that just darker than base white and the last step as that just lighter than black.
Ilford MGT.44M warmtone RC gives the same number of steps at grade 2.
I am using a colour head with 41Y, 32M for grade 2.
Grade 3 gives 10 steps visible.
From memory I think the overall contrast of Ilford multigrade FB is similar to Agfa MCC.
10 steps looks about right. I got 9 on MG IV WT, and 11 on MG IV. Some very old Tetenal (=Agfa) gave 14 steps at grade 2, but is on the verge of fogging.
-- Ole Tjugen, Luddite Elitist
Paper has a gradient of around 2.00, while film has a gradient around 0.50. Film takes the average scene of around 7 stops and reduces it on the negative to around 3 1/3 stops. The paper extends it back to the seven stop range (DR 2.1). That means a one stop density difference on the paper equals a 1/2 stop DR from the negative or in your case a timed exposure. And a 1 stop DR on the negative equals a two stop density difference on the print. It's late, so I may not be expressing this concept too well.
I hope I don't throw the topic of this thread.
But, umm, talking of Ilford, any news reguarding whether the chemicals are in production yet? Could really do with some.
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Originally Posted by Stephen Benskin
I think you lost me there...... DR ? ( Dynamic Range? What units?) How does the paper and the film DR relate? There is an expnsion and a contraction going on?
It's a case of input to output. The average scene has a log subject luminance range of 2.2 or 7 1/3 stops. With flare, it is about 1.80 to 1.90. If the resulting density range of the negative (DR) equaled the scene's luminance range, the negative DR would be about 1.80, but it's not. The aim DR for a diffusion enlarger is around 1.05 or just over 1/2 the input. That would be a slope of around 0.58 or a Contrast Index of 0.58. The equation to calculate the slope of a line is rise / run.
In order to have the printed image approximate the range of the original subject, the paper must have around twice the slope of it's curve. The basic equation is Slope Neg x slope paper = 1.00. A value of one, or unity, is an approximate 1:1 relationship between the original subject and the resulting print.
If you are curious to read more on this subject, it's known as Tone Reproduction Theory.
I don't know if this will help any, but I've uploaded a Tone Reproduction Curve. It represents the relationship of each of the steps in the photographic process.
That was a good explanation. Thank you. I can understand ( a bit) from your description what is happening, and why I get only 5 zones of paper density. I guess I was surprised ( without the theoretical background) at my findings.
I will go find more to read and understand from your quickie response...