I've been working with CTP for over 6 years and still haven't got a plate densitometer? We've allways checked our plate quality with a standard control wedge indicating checkerder circles of 1px X 1px, 2px X 2px, 3px X 3px, ... on a standard screened 50% background.
Why should I buy an expensive plate densitometer and what brand/type is to be recommanded?

I know what yoyr saying the plate densitomitors are vere expensive but you said you screen a 50 % background , how do you know its 50 %. Also how do you calibrate the rip to make sure the plate is outputting a 20% screen or a 50% screen. these values have nothing to do with your exposures. If you are looking to improve your quality buy one, calibrate the colors and black and check out the difference. You'll wonder how you never knew about the calibrations before. It will also tell you if pre press isthe cause for the pictures that look muddy or if it is the photo, or press. Are you tired of being blamed for the quality of the paper. this will tell where the problem is.

You can never match standards correct and accurate or truly tune your proofs without it. We have many presses that all print to the same standard proof. The way we pull that off is by using a plate reader, calibrating plate curves to normalize all presses to an average. If you want to do real quality color and have good control of color, it's a must. The good ones are about $5000 and there are some posts on here about this.

Prepress Forum, Plate Reader
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Prepress Forums and Graphic Design Forums, the online Graphic Arts community. The Printers, Publishers, and Designers Prepress Supersite!
http://software-robotics.com/graphic-design-prepress/viewtopic.php?p=5696

Prepress Forum, Quality Control in computer to Plate CTP, + or - 2 ...
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rep for our plate reader company (Ihara), and essentially told me that >> is the tolerance of the plate reader. Which leads to more questions in ...
http://software-robotics.com/graphic-design-prepress/viewtopic.php?t=506

Prepress Forum, Plate sizes and the Heidelberg Suprasetter A52
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As for the plate reader, I do not know where you are located and the policy may very depending on the local Heidelberg organization. The Chemfree plate has ...
http://software-robotics.com/graphic-design-prepress//viewtopic.php?p=3230

Prepress Forum, Screen Lpi Rulings, FM Stochastic or Conventional
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I got my new xrite platedot plate reader in today, they were on back order so I got the salesmans demo unit, has the stochastic screening upgrade, ...
http://software-robotics.com/graphic-design-prepress/viewtopic.php?t=152

Prepress Forum, Screen test pattern, Testing Screen PTR 8600E plates?
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What type of plate reader do you have to calibrate with? You really need a video dot reader like Beta or Xrite Dottie to properly read the plates. ...
http://software-robotics.com/graphic-design-prepress/viewtopic.php?p=4186

Prepress Forum, Luscher Xpose, CTCP or Thermal Computer to Plate ...
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I have took images of dot from BasysPrint with Troika plate reader, and it looks exactly like one could expect from device 1270Dpi/175 Lpi... ...
http://http://software-robotics.com/graphic-design-prepress/viewtopic.php?t=1066
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Last edited by joepostscript on Oct 27, 2007 6:55 am; edited 1 time in total

I reccomend looking at X-rite for a densitometer

Hi ,
I have used the X-Rite 518 and 520 for testing the plate.I think It is very good.

Noregret

Now that Xrite bought everyone else, that's about all there is. Don't scrimp on Plate readers or densitometers, they are really important. For reading dots on a plate, a video plate reader like CCdot etc is so much better than a densitometer. But if your budget is tight, a good densitometer will do.
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I agree that a densitometer is better than nothing, but CCD plate readers are usually preferred as they analyse the captured image based on the image contrast to the background, therefore giving accurate and consistent results. Different kind of plates (conventional, thermal, photopolymer, of various brands) differ in non-image area reflectance and graininess, can fool a densitometer in various ways.
I once made an experiment comparing an IC-Plate reader (CCD) to an LED-illuminated portable densitometer when reading a Kodak violet photopolymer plate dot percentages. The results differed by a lot. I also measured the same percentage area (say 20%) several times with each one: the CCD was always spot on; the densitometer had huge variation, reading anywhere between 10 to 35 percent, totally unreliable; also seemed to prefer a particular angle i.e. holding the instrument perfectly straight, parallel to the plate edge. Then it struck me, it might have to do with something along the plate, on its surface, as it's being processed/developed. Could be the gum, so I quickly cleaned the plate and bingo, the densitometer readings matched the CCD device.
However, the CCds are better - more reliable, more accurate, you don't need to take any precautions, no need to calibrate etc.
One more thing to note - the absolute accuracy of the instrument is of less importance, as long as you use that instrument only. Even if a 50 percent patch is 54 in reality, the pressmen will learn to compensate that over time - you will feed them with plates that are a bit wrong in the same way, and by the same amount.
Just a thought.

You should check out the PlateScope by Techkon. It's a German company, but available in the USA. It's MUCH faster than Xrite, and more accurate than icPlate or ccDot. There is NO extensive calibration required, it's a simple white spot built onto the charging cradle. It also has features to export pictures of the image to whatever you want, and the Pro model lets you calibrate your CTP curves. It can also read color, although it took some experimentation to figure out how to "read" it. You can measure the dots on screen, in microns, if you want actual dot sizes, and it has a 4X zoom also, and can store several hundred readings that you can then download into your computer later. It costs about the same as the rest, but it is a lot easier to learn and use. The Xrite takes forever to calibrate, and several seconds to take a measurement, and about 30 seconds to come on. The Techkon starts up in 3 seconds, takes about 5 seconds to calibrate, and takes a reading in one second. I tested the Techkon, Xrite, icPlate, and ccDot, and my preference was the Techkon, icPlate, Xrite, ccDot, in that order.

CreoUser,

I've never seen/used a Platescope, but:
- The Platescope is a genuine XRite product, isn't it (well, according to their website),
- it's enormously expensive,
- (former Gretag) icPlate is nippy enough and doesn't require any calibration, much like many other CCD platereaders,
- for someone who never bothered to calibrate his percentages, any ccd- device will do... just like most of the plate densitometers, for that matter.

At my shop we run Staccato screening all the time and my plate has to be super accurate. I have a Gretag densitometer and it is not good enough to read the plates. Why? Plates have grain and when you use a densitometer it uses reflected light in order to get its readings. A plate reader on the other hand takes a picture and reads the data based upon contrast not reflected light. Most plate readers are within one percent on accuracy. Believe me, at my shop we have to have extreme quality control and a densitometer just doesn't cut it. Also, if you are not checking your plates you have no idea what you are actualy printing. Throw in press variables, grey balance and dot gain and it gets really interesting. READ YOUR PLATES !!!!
You be the expert. You control what the pressroom gets and you set the standards for your plates so you can reproduce work over and over and know you are getting the same results every time.

James 007
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James Fifer/Print USA: Kodak Prinergy Rip, Staccato Screening 20Micron, Color Specialist and all around Pre-Press Dude.