How to read Concentric dots

[Reece3]

What will read concentric dots correctly on our plates. We use Fuji NI3 plates and our CCdot does not read the concentric but reads our round dot fine.

Thanks,
Ken

 

[gordo]

What will read concentric dots correctly on our plates. We use Fuji NI3 plates and our CCdot does not read the concentric but reads our round dot fine.

Thanks,
Ken

Well you could try using a densitometer. Despite what vendors of plate readers tell you there are many shops that measure their plates that way. There is also one major vendor of presses and CtP that I know used to do it that way also ( I don't know if they still do though).

The method is explained here: The Print Guide: Using a densitometer to measure plates

Start by comparing what your plate reader says about round dot imaged plates compared to what the densitometer says. That way you can calibrate your densitometer's N factor to improve accuracy.

Are you actually using concentric dots or are you just testing? Why are you making the switch?

Best, gordo

 

[Reece3]

We are using concentric dots. I will read up on the link you sent. Thank you for the timely reply.

Ken

 

[RickS]

We use a Gretag IC Plate II with concentric dots on Fuji LHPJ plates no problem. I will tell you that we had a problem in the past with measuring on a surface that was not flat. We now measure with the plates laying on a 3/4" plywood surface.

Rick

 

[D.M.]

Similar to RickS. I use iCplate II for concentric dots. Also I have Platescope. There is "small" difference between those two instruments. I average measurements.
What more, for concentric screening I am using Fogra (FMB) and FM option, for round dot - generic and AM option. Works pretty fine as long the surface is flat and all conditions remain the same (I suppose even temperature is important). To be clear, CtP is Kodak Magnus 800 processing Kodak Electra XD plates.

BTW I am interested in concentric screening and how another print-shops manage with it.