Loris,sorry to say that step 9 actually couldn't be seen on the tablet. I coated an area of 5X3 and torn the paper in two for the highlight and shadow steps of the 31 step tablet to save chemicals(ashamed that I've already wasted so much). I could have an integrate one for the 21 step tablet though. I'd do it again for a better judgement. Should I still expose for 40 mins?
Sudek I'd suggest that you make the tests at final print size - or at least 8x10" if not practical. Small coating areas vs. normal or big can make quite a difference and it's hard to coat evenly at small sizes. You do not need to expose for 40 minutes for the (hopefully) last test, 20:00 would be more than enough.
Loris,I used to coat an area of 4X5 inches which would be one of my final print sizes.When I found it made defferent when the extra water in the brush drained out,10-drops I applied before is sufficient only for 3X5 inches.I should have sticked to the size and varied the drops.The attached is the newly made strip exposed for 20 mins.The steps changed to black one by one beginning from step 2 when I applied the threshold layer.Does that mean I have no merging steps? Also I could see the boundary between OHP and the paper(I covered all of the tablet this time).Does that mean I should expose for a longer time,30 mins for example?
Loris,I just read the K value of each average step on the 31 step tablet exposed for 20 mins.
From step 2 to step 10, it reads as:90%,90%,89%,89%,88%,87%,85%,82%,79%.
From step 28 to step 31,it reads as: 8%,6%,5%,4%.
The paper white reads as 3%.
And for the one exposed for 40 mins before,from step 2 to step 8 all read as 83%.
If the steps have the same K value, does it mean that they're merged? And why the steps of the same K value can't turn to black simultaneously on the threshold layer?
Sorry for the childish questions. Many thanks!
When I process the same file, I see dmax exactly at step 3. (See the attached image... Steps 2 and 3 turn black together, that means they're merged.) Since the emulsion is under step tablet + OHP and you won't have the step tablet with real prints, the dmax is at virtual step 4. (Virtual, because there's no step tablet anymore. And the UV density of the step tablet is ~1 step with the 31-step tablet. Note: 31-step tablet has log 0.1 density steps, that is 1/3 stop difference per step. The 21-step tablet has log 0.15 density steps, 1/2 stop per step.) Since you want dmax at virtual step 1 you must decrease exposure by 4 (current placement of dmax) - 1 (ideal placement of dmax) = 3 steps. That is exactly 3 x 1/3 = 1 stop. Therefore, your standard printing time should be 20:00 - 1 stop = 10:00 minutes, (VERY IMPORTANT) as long as you keep all the process parameters (formula, coating volume per area, environment, processing etc.) the same.
Hope this helps.
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Each K value is equivalent to 2.55 RGB value and you're experiencing rounding with the K values. Working with a desaturated RGB files gives a little bit more mathematical resolution than grayscale files.
One more note:
With print out processes it's better to start with a little less dmax, to avoid the toe of the sensitometric curve. You'll get a little less dmax (it's fine as long as it's convincing) but much better tonal separation and detail in the shadows - right because you'll start closer to the straight portion of the curve.
So, don't fuss too much about dmax; focus on making the tonality sing. Viewers wouldn't be able to discern 1 step difference of dmax in normal viewing conditions - when the print is under glazing!
Loris,thanks so much for the detailed explanation.I never dreamed that I could have an exposure time as short as 10 mins.
And I just received the "magic brush" today after a long wait.I should do the test again,right?
As for the process parameters,can the temperature/relative humidity be regarded the same in certain range? It seems a bit difficult to keep them remain exactly the same.
Tons of thanks!
Sudek, it's CRUCIAL to keep all parameters listed below UNCHANGED for the initial / calibration tests:
- Paper, (obviously)
- Formula, (obviously)
- Coating volume per area,
- Coating method, (if it's a brush, try to keep its moisture content stable too...)
- Environment, (that is: temperature and RH - small variations are OK)
- Drying method & time,
- Pre-humidification method & time (if applicable),
- Negative material, printer/inks and printer settings, (in case of digital negatives)
- Lightsource, contact frame/glass and exposure time,
- Post-humidification method & time (if applicable),
- and all of the wet processing steps.
You can relax later when making real prints. Because after awhile, you'll gain experience on how each parameter affects the end result. But for calibration, it's better to act in an obsessive-compulsive manner, in order to avoid problems / confusion later... (I'm sure you hear me about it!)
Since you're at the very beginning, I'd suggest you to start from scratch, using a test coating area / volume equal (or close) to the final print size. (I always calibrate for 8x10" print size - that's the smallest size I print...)
Good luck & regards,
Last edited by Loris Medici; 03-12-2014 at 02:31 PM. Click to view previous post history.
Reason: Added the contact frame/glass & negative material...
Loris,thanks so much for the kind suggestions.Sorry that I have questions again with the result coated by the "magic brush".
Is it abnormal that the uncovered part(neither step tablet nor OHP) on the coated paper got less density compared with the covered part? And it looks like solarization.I used 8 drops(4FO+4Pd) and 10 drops respectively and lower density on the uncovered part are the same.
And I found that if I drew different size of selection on each step,the result for the darkest or merged steps could be different,so did the K value.For example,with some size of selection,I got step 1 and 2 being the darkest and merged for the 8-drop strip.And step 1,2,4,5 the darkest and merged for the 10-drop strip.But the result may change a little bit for different size of selection.And I'm confused too on which strip I could based judgement,or neither? The TEMP/RH is about 18/60% for both strips,the previous condition (with the old brush)is about 17/64%.Does the RH variation matter? Sorry for all the trouble.