Help with Densitometer

[Will S]

OK, I've got a densitomer now. It's an older one (Marshall Labs from Indiana - or am I thinking of my amp?) that just does b&w. I understand how to measure with it, but I would like to see if it is close to being correctly calibrated. I'm guessing I need to buy a Stouffer Step Wedge of some kind and measure the densities on that to see if they match. Will the step wedge come with something to indicate what the densities should be when read? Which step wedge should I get?

Also, for testing paper what wedges do I need- the transmission projection for 4x521 step, or just the RZ9 zone system chart? And for testing 4x5 film? Hopefully it would be the same wedge as for testing the densitometer.

If there is a book that covers all of this please let me know.

Many thanks in advance,

Will

 

[Donald Miller]

The twenty one step tablet from Stouffer will do the trick for you. Typically for the uncalibrated tablet the first step measures a density of .04 and then each step is .15 addtional. Good luck

 

[Zathras]

OK, I've got a densitomer now. It's an older one (Marshall Labs from Indiana - or am I thinking of my amp?) that just does b&w. I understand how to measure with it, but I would like to see if it is close to being correctly calibrated. I'm guessing I need to buy a Stouffer Step Wedge of some kind and measure the densities on that to see if they match. Will the step wedge come with something to indicate what the densities should be when read? Which step wedge should I get?

Also, for testing paper what wedges do I need- the transmission projection for 4x521 step, or just the RZ9 zone system chart? And for testing 4x5 film? Hopefully it would be the same wedge as for testing the densitometer.

If there is a book that covers all of this please let me know.

Many thanks in advance,

Will

There is a book that covers all of this called "Beyond The Zone System", by Phil Davis, that covers all of this in great detail. It is heavy on the technical side,but after reading it a few times, the concept will sink in. Phil Davis also has a website that deals with this at http://btzs.org

There are a few discussions on this topic in the APUG forums. Just do a forum search with "btzs" as your keyword.

Mike Sullivan

 

[Kirk Keyes]

OK, I've got a densitomer now. [...] I understand how to measure with it, but I would like to see if it is close to being correctly calibrated. I'm guessing I need to buy a Stouffer Step Wedge of some kind and measure the densities on that to see if they match. Will the step wedge come with something to indicate what the densities should be when read? Which step wedge should I get? Will

Will - for calibration, check out these standards from X-Rite
http://www.xrite.com/product_accessories.aspx?Line=17

3 Step Certified Wedge (Transmission), Part Nr. 319-68, $41

Calibration Step Wedge for Models 810-830, Part Nr. 810-68, $71 (This is for reflection which your densitometer may not do.)

3-Step Calibration Plaque (Reflection), Part Nr. 302-12, $39

You can buy online from X-Rite which makes it really convienent.

I bought a set of 810-68 and 302-12 for my Noritsu DM-201, and even though these are made by X-Rite, they work just fine.

 

[Nick Zentena]

The stouffer calibrated wedge is a little more money then the plain one. All they do is read it on thier machine and hand write the exact values.