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Halftone file for DIY films/screen testing and some pointers on calibration

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blue moon:
attached is the halftone test file for the screens and films.
This is what we use to calibrate the film output and see what we can hold on the screen.

Anybody interested in getting their RIP output calibrated can send the films to me for readings. I check it out and email the values to be entered in the RIP to produce calibrated output. My time is limited, so I can commit to one or maybe two of these per week. Films will go in the queue and will be checked on first come, first served bases.

If using it to check the screens, see what is the smallest percentage that opens. It is OK to spend a little bit more time washing those out, as we work harder in those areas too. What matters is that you can repeat the results.

For anybody sending the films to us, I very strongly suggest printing two copies and saving one as a reference. It is also a good idea to actually fill out the information on the top (instead of leaving our info) so you know the settings used. I've found that over the years we switch this and that and I have reference films that I don't know what's on them. Gradient and opacity should look the same. If there is any variation, there is a problem with your software.

45lpi is a good place to start as it is in my opinion a minimum needed to produce good prints (7-85% should be good). At 45lpi those numbers should be achieved pretty easily. Step up is 55lpi in 5-90% range and to get really good anything at 55 or smaller in 3%-95%. 230 mesh for 45lpi and 305 for 55lpi. These are guidelines, not rules, so feel free to experiment.

Let me know if there are any issues with the file. I have it as an ai and eps if needed.

pierre

blue moon:
few things to look for is any banding in the gradient strip, jaggy transition from halftone to solid on top of the strip and closed in dots at 90% or more. Your film output device should be producing very small holes at 99% whereas 100% should be solid.

traditionally, ghostrip produced 60%+ at 50% and AR is usually above 70%. This is based on tests with our equipment and other ppl sending films for reading.

pierre

blue moon:
and here is ball park what a 50% image should look like. The rows should be slightly closer together, but the distance (end to end) between the dots is about right.

If your dots are joining before 70%, the dot size is too big.

pierre

Screened Gear:
Pierre,

I applaud your willingness to help here. You my friend get 10 respect points.

Screened Gear:
Well I haven't looked at my printers dots in a while. I think I need to calibrate it a little (not as smooth as they should be)

Here is my 50 and 45% dots. I am off but not as much as i figured. Still need to get my rip set perfect for my new printer. These photos are at 800 percent magnification. I know a little over kill. They are also blurry.

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