Kiwo XTS

[LuckyFlyinROUSH]

Having trouble dialing in Kiwo XTS curve. Anyone happen to have an uncorrected and corrected curve we could try out. Screen shots work.

The lower percentages are printing too small of dots, and higher is printing too thick.

[Dottonedan]

Where did this current halftone curve come from?
Is it the manufacturer default or is it an adjusted curve by the Tech?

I take it that you have already tried determining if your exposure time is exact for this devise.
You may have some latitude in you window for true exposure to go a little less time, allowing you to hold that small dot better….and still be truly exposed. Fractions of a second or something.

[Dottonedan]

And remember, you would not normally be able to hold a true 2% dot anyways.  Those of us that do hold a 2% are not using a true 2%.  Both Douthit and M&R’s 2% dots are more like 4-7% dots.  This is why everyone thinks these hold such great detail “better” than film but in reality, they are not accurate. They are beefed up to hold better. They do expose better than film  (because they are Direct To Screen).  There is nothing wrong with this. It works well. But the idea of holding a true 2% is not likely.  Most all mesh threads are thicker than a 2% and will be blocked.

You should also be able to just manually bump the 2% to a 4% in your curves. Unless they did not instruct you on how to do that. A lot of them are very similar to curves in Photoshop.

[blue moon]

both of those coverages look about right. Are you talking about the amount of ink to create those or the actual dot sizes?
pierre

[LuckyFlyinROUSH]

The Kiwo unit is so different from the I-Image I'm having a hard time wrapping my head around it. Colorprint is easy to just manually change the input to output curve. They are trying to explain it over email...which is impossible. There are two different kiwo curves, one uncalibrated, one calibrated. Not sure why you can adjust both. Attached.

Here is an excerpt from the email: Input values are art to RIP. Output values are RIP to XTS. If you enter a "50%" output value for a 2% input value, you are telling the RIP that your output device (XTS) is printing a 50% dot when it should be 2%. This triggers the RIP to compensate for the dot value (50%). It basically thinks we are printing 50% when it should be 2%, so it makes the 2% dot smaller to compensate. At a jump this large, your 2% dot is going to be microscopic. Not just 2%, but everything up to 50% is going to be much much smaller.

This all seems extremely backwards to what I'm used to.

If I wanted 2% to output as 6% so I can actually print it on the I-image then I'd just drag the curve to output as that.
I do know the I-Image we can get a 3% dot easy...but I bet you are right, it's probably outputting at 6%. I don't have a real way to measure it, but I do know that the prints look good and dots image correctly. The Kiwo is currently printing dots so small I can barely see them.

[LuckyFlyinROUSH]

Attached is what the I-Image 2 and 90% look like. The dots are larger so we can actually expose them, and 90% doesn't fill in at a 4 second exposure.

[blue moon]

those dots are not even close. your 2% looks to be over 10% (I would guess about 15%). your 90% looks like 75% or so.
you will not be able to hold a true 2% dot. It is way too small. 90% is almost completely closed. You should just be able to see a little bit of an opening. Your Kiwo dots looked about right (judging by eye from memory)
pierre

[blue moon]

p.s. with a 4 second exposure my guess is your are using a starlight. It has a pretty bad light field with large variance (20%) and a lot of undercutting. That would explain why you need a big dot that shows up small on the screen. In the end, you should calibrate based on the results on the exposed screen. This will take into account any losses due to undercutting.
EDIT: all the measurements were taken many years ago, not sure if they changed the LED type or layout since then!

[blue moon]

The Kiwo unit is so different from the I-Image I'm having a hard time wrapping my head around it. Colorprint is easy to just manually change the input to output curve. They are trying to explain it over email...which is impossible. There are two different kiwo curves, one uncalibrated, one calibrated. Not sure why you can adjust both. Attached.

Here is an excerpt from the email: Input values are art to RIP. Output values are RIP to XTS. If you enter a "50%" output value for a 2% input value, you are telling the RIP that your output device (XTS) is printing a 50% dot when it should be 2%. This triggers the RIP to compensate for the dot value (50%). It basically thinks we are printing 50% when it should be 2%, so it makes the 2% dot smaller to compensate. At a jump this large, your 2% dot is going to be microscopic. Not just 2%, but everything up to 50% is going to be much much smaller.

This all seems extremely backwards to what I'm used to.

If I wanted 2% to output as 6% so I can actually print it on the I-image then I'd just drag the curve to output as that.
I do know the I-Image we can get a 3% dot easy...but I bet you are right, it's probably outputting at 6%. I don't have a real way to measure it, but I do know that the prints look good and dots image correctly. The Kiwo is currently printing dots so small I can barely see them.

the linearization is actually pretty easy from what it reads in the email. Just enter the values you got from the spectrometer into the boxes and the RIP will adjust.
so read the 2%, 10% and all the other dots. then jot the results in corelating boxes. that should be it.

pierre

[LuckyFlyinROUSH]

Where can I buy one of those?

If I'm having the issue with the starlight undercutting, it's probably why I have to have my dots much larger in the lower, and much more opening in the higher, as it fills in upon exposing.

[blue moon]

Where can I buy one of those?

print it on a piece of paper and send it to me, I'll take the readings and let you know.

you can get spectrometers on ebay or directly from manufacturers, but a good one will be expensive.
In general you will have a hard time reading the dots on the screens due to the color of the emulsion and mesh interference. So you would need to take the readings from a print. That means you would be using a reflective spectrometer. So if looking for one that's the type you'll need.

pierre

[blue moon]

sorry, you need a densitometer. the other one is for measuring light. . .
pierre

try here:
https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=reflective+densitometer

[blue moon]

this looks like a good option. Don't know anything about the software. It might not be compatible with Win 10, you'll have to do some digging. X-Rite makes good stuff. maybe call them and see what they say.
https://www.ebay.com/itm/372637839409?hash=item56c2f23031:g:pRoAAOSwZ3pb9wW9
pierre

[LuckyFlyinROUSH]

Hmmm... I'll do some digging.