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Topic: Focus and fluence tests (Read 40 times) previous topic - next topic

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  • Farabomb
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  • #NoLivesMatter
Focus and fluence tests
I'm trying to fix our plating issues. All the targets I have are for positive plates. The Azura TS is a negative plate. Does the target matter or do I need to invert the image? I only ask because the first test I ran didn't produce the results that were expected. I don't want to waste more plates going down the wrong path.

The thickness tests all look the same when they should be visible differences but I'm not seeing them. It's possible I'm doing the test wrong as well. I think I need to go back and test the fluence because if that's out it affects the thickness (focus) as well.
Speed doesn't kill, rapidly becoming stationary is the problem

I'd rather have stories told than be telling stories of what I could have done.

It's more like grip, grip, grip, noise, then spin and 2 feet in and feel shame.
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  • Ear
  • [*][*][*]
  • Fiya wata
Re: Focus and fluence tests
Reply #1
On my Screen device, we enter the plate thickness in mm, then expose a focus test plate from the platesetter service menu. It spits out patterns that are visible with loupe or plate-reader. It's similar to the old graybar that your would expose with halftones, to determine range. You should see a soft screen and your optimal focus will be right in the middle of the curve.
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  • Ear
  • [*][*][*]
  • Fiya wata
Re: Focus and fluence tests
Reply #2
... I usually look at the current plate config to see focus. When I run the test, it asks for a focal range and a start point on the plate. I usually go a fair amount in either direction of current focus.
Quote: Skryber  "FreeHand sucks ferocious porcupine balls!"

Quote from: born2print "Well now doesn't that suck petrified possum penis."

  • Joe
  • [*][*][*][*][*]
  • Administrator
  • Master of Nothing
Re: Focus and fluence tests
Reply #3
I'm trying to fix our plating issues. All the targets I have are for positive plates. The Azura TS is a negative plate. Does the target matter or do I need to invert the image? I only ask because the first test I ran didn't produce the results that were expected. I don't want to waste more plates going down the wrong path.

The thickness tests all look the same when they should be visible differences but I'm not seeing them. It's possible I'm doing the test wrong as well. I think I need to go back and test the fluence because if that's out it affects the thickness (focus) as well.

Just use the same target. Shadow end becomes highlight end and vice versa.
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  • Farabomb
  • [*][*][*]
  • #NoLivesMatter
Re: Focus and fluence tests
Reply #4
Yeah, same here. I use the current settings in the middle with higher and lower flanking them. What I'm wondering about is if the test image matters if it's positive or negative. It shouldn't matter is what I'm thinking but when I ran the tests yesterday I did not see a difference between any of them.

I did put a micrometer on the plate and what should be .012 actually was slightly under .011. I'm going to run both focus and fluence tests with 2 different sets of values. One based on the .012 that's listed and one based on the .011 that I'm actually seeing.
Speed doesn't kill, rapidly becoming stationary is the problem

I'd rather have stories told than be telling stories of what I could have done.

It's more like grip, grip, grip, noise, then spin and 2 feet in and feel shame.
I once knew a plus-sized girl and this pretty much describes teh secks. :rotf:
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.
         --Benjamin Franklin

My other job