what lpi is better to print?

[mightyjack]

I have an herkules pro imagesseter, and I print on a Heidelberg MOFPH.
Can anyone tell me when I make my films what value is better to set? 175 lpi, 225 lpi? 150 lpi?
Also I have just buyed a Gretag Macbeth 19C densitometer and I have troble using it.
Any advise is usefull about how to print better, because right now I am not satisffied with my results.
Thank you

 

[RichardK]

Hi

depends on what paper/ink really. For example coated art paper with good quality inks and all rollers/blankets in good condition as well as high res scans with good tonal range you should be looking at 175lpi as a minimum.

Maybe Mr Heidelberg can say whether the MO is capable of higher screen rulings without filling in of the shadows.

You don't say what aspect of the print quality you aren't happy with, can you expand on this and perhaps we can help you get better print quality? I doubt whether screen ruling on its own would give you disappointing printed results.

 

[mightyjack]

thank you

thank you,
yesterday i have noticed that the guy from out prepress departament was using 240 lpi, what is too much i thnik if you don't have CTP.
This weeke someone gave me an Gretag Macbeth D19C densitometer and I am tryng to find out how to interpret the results from him.
Mostly I am not satisfied in my color management, because I depent soo much on the guy that prints (If he is not tired, he can make good jobs, if not.....) That is why I have looked for a densitometer, to not depend on his eye.
I have used the densitometer to measure density wich was usefull. But when I umeasured dot gain I have the results from solid anf from halftone at 80% and at 40%, where I had results in procents (between 12 - 20%). In imagesetter settings there is a place that asks me values from 10 - 100%.
Is there usefull for me to activate the rest of the functions? Hue erorr, traping. How do I use this to improve my printing. I am asking this things because is hard to find good people in Romania. There might be but I don't know them

 

[5150pressman]

On the 19c has all those functions like trap, dot grain, hue etc.
Whoever had the 19c before had to have paid for each of the function.
When you buy the 19c you could have just bought it to read density and nothing else. Adding EACH function I think is $150 US dollars. I think you got a price break if you bought every function.

As for the imagesetter and the dot values.
It goes something like this.
You need to print a percentage scale from 10%-100 solid in 10% incriments.
10,20,30 etc.
If the 19c is calibrated you take the reading of the scale and plug in the numbers to the imagesetter.

I think someone with know more.

 

[5150pressman]

As for what line screen to use. Like Richardk said. If the press is in good running order min on coated stock 150. I think you might be able to do 200.
Uncoated the max in those condition 175 line. but 150 line would be on the safe side.

 

[mightyjack]

ok

the screen lines I undrestand I will take it slow from 150 or 175 and if possible reach 200.
I think that I have to contact the ones at Xrite for the functions.
These days I want to make further tests, because I realy want to improve my quality but I don't have the know how.
I also have a desnitometer for film, but I do not know how to use it and how to measure. Over the table with light? Do I keep the light on? Must it be off? How do I calibrate the imagesseter?

 

[RichardK]

Assuming you have Euro inks and gloss art paper stock aim for

C 1.34 M 1.34 Y 1.15 K 1.80 on the 100% colour patches

Use this a guide only since you're not selling colour bars but the job.

Re: the film densitometer, you need to establish the min density and max density of an exposed film (Dmin Dmax) with fresh chemistry in your processor. so choose a blank part of the film and measure then a 100% part and measure. Record and use as your reference figures.

To use the densitometer, place the films' target area between the cell and the footplate see pic attached, then read off the values.

As for calibration of the imagesetter I can just about recall how it's done (it was 8 years since we had one) but rather than give you poor information maybe another member who has one running (and there will be quite a few still around), may be able to help.

 

[mightyjack]

ok

very helpful information you are giving me so thank you
my densitometer for film has the folowing measures
DOT
DOT SOFT
NEG DOT
NEG DOT SOFT
DENS

so wich one do I measure the Dmax and D min. Is it Dens?

Why does it have 2 buttons.

I am sorry that I ask soo much but I have no instructions for it.
It is good to know that the solutions must be new

 

[RichardK]

Den would be the one. The others relate to hard or soft dot film. Two buttons? One may be to zero the device on clear film before you press dens for dmin/dmax testing.

try viptronic.com for an instruction manual.

I'm trying real hard to recall the dmin and dmax figure we used to run to... .01 dmin and 4.5 dmax seem familiar. What dmin/dmax figures are you achieving at present with fresh chemistry?

 

[mightyjack]

not working

unfortunatly vipdens.com diverts to xrite.com, where is impossible to find anything about the model that I have Vipdens 130.
If you can remember please tell how I must do the measure? Over white paper? Over table with light?

 

[RichardK]

Transmission densitometers have their own light source built in.

Place the film between the flat plate then bring the top of the densitometer onto the clear part of the film, then press the zero button then the dens button to read the dmin - let the head of the densitometer spring back to the open position then move the film to the 100% point ie the darkest part of the film, then press the body down again to read the dmax. Make a note of the figures and then monitor on a regular basis. If your dmax on 100% drops below 3.5 then you need to replenish your chemistry.

 

[muminn]

Quality Improvements

First of all, for better quality you must ensure that you have a good guy in printing press. That is your finish output. Everything depends from your printing machine, nor just from process (Design, Prepress, Film, Plates, etc).

From my experience, you must be sure that your machine is in good condition. To do this, you better find or ask for a Test Film from a specialized prepress company with detail specifications of prints. Be sure that you get a proof instead. For example. A printed magazine cover!

Then, you look forward to imagesetter or your plate developer.

Anyway, I recommend you to find an expert for further improvements.
Quality, always needs care and that job can be done only by a professionals.

Regards,

 

[RichardK]

Sometimes one overlooks the obvious...

Muminn has a better grasp here of the issue than me.

Doesn't matter if everything else, equipmentwise, is top notch if the operator is not skilled enough or not motivated enough.

 

[printuniverse]

The company you are looking for might be FAG GRAPHIC SYSTEMS SA, please send me your email address. i have a vipdens c3 manual in pdf format. it might help you out. although, i must say that after using this brand of densitometer, i had to purchase an xrite, due to inconsistencies of measurement values. In my country, the authorized dealer cannot repair/calibrate this brand of densitometer.