1500 dpi only

[maxon]

Can anyone please give me an accurate technical explanation on how can a 1500 dpi addressable resolution CTP machine be able to expose high quality plates at a screening of 175 or 200 lpi. We are purchasing a 10-colour B1 size sheetfed machine and evaluating various CTP offers. I would welcome any technical arguments not marketing gibberish. Pure technical arguments regarding exposure quality of such a machine compared to CTP engines with native 2540 dpi or better. Thank you all.

 

[gordo]

Can anyone please give me an accurate technical explanation on how can a 1500 dpi addressable resolution CTP machine be able to expose high quality plates at a screening of 175 or 200 lpi. We are purchasing a 10-colour B1 size sheetfed machine and evaluating various CTP offers. I would welcome any technical arguments not marketing gibberish. Pure technical arguments regarding exposure quality of such a machine compared to CTP engines with native 2540 dpi or better. Thank you all.

If you are concerned about the system's ability to render grey levels - the answer is here: Quality In Print: Grey Levels
(read art one before part two.

It has nothing to do with exposure - just the screening algorithm.

1500 dpi is interesting though - most systems would use an even multiple of 2400 or 2540 - i.e. 1200 or 1270 dpi.

best, gordon p

 

[andreisarbu]

1500 dpi

1500 dpi

Basys used similar resolutions with Ok results...

 

[michaelejahn]

if using Grating Light Valves, maybe !

if using Grating Light Valves, maybe !

Can anyone please give me an accurate technical explanation on how can a 1500 dpi addressable resolution CTP machine be able to expose high quality plates at a screening of 175 or 200 lpi.

Well, in a word, no.

I would need a bit more information on what imaging technology is being used.

Placing two 1/1500th of an inch wide 'spots' with a 1/1500th of an inch space between them is one thing, and creating 'screening' is another thing all together.

For example - in the Agfa :Avalon LF - they use Grating Light Valves in their Computer-to-Plate Light Modulators

Welcome to Silicon Light Machines

So, the answer would largely depend on the design, but lets face it, that is all marketing noise - send some file, have them make some plates and do a press test.

That's what we always did.

 

[marktonk]

You may also want to check out the laser spot size. This is different then the addressability which is 1500 dpi. If the spot size is large 17 or 20 mircons, you will see a difference in imaging fine detail compared to a laser with a 10 micron laser spot. With a larger spot size, I have seen slur bars where the center was elliptical instead of round. The laser spot size was 20 micron and the plate was not very high resolution. You will also see a difference on very fine type.

Regards,

Mark